Manual of Surgery/Chapter X

CHAPTER X

TUMOURS[2]

Definition--Etiology--General characters of innocent and malignant

   tumours. CLASSIFICATION OF TUMOURS: I. Connective-tissue tumours:
   (1) _Innocent_: _Lipoma_, _Xanthoma_, _Chondroma_, _Osteoma_,
   _Odontoma_, _Fibroma_, _Myxoma_, _Endothelioma_, etc.; (2)
   _Malignant_: _Sarcoma_--II. Epithelial tumours: (1) _Innocent_:
   _Papilloma_, _Adenoma_, _Cystic Adenoma_; (2) _Malignant_:
   _Epithelioma_, _Glandular Cancer_, _Rodent Cancer_, _Melanotic
   Cancer_--III. Dermoids--IV. Teratoma. Cysts: _Retention_,
   _Exudation_, _Implantation_, _Parasitic_, _Lymphatic or Serous_.
   Ganglion.

[2] For the histology of tumours the reader is referred to a text-book of pathology.

A tumour or neoplasm is a localised swelling composed of newly formed tissue which fulfils no physiological function. Tumours increase in size quite independently of the growth of the body, and there is no natural termination to their growth. They are to be distinguished from such over-growths as are of the nature of simple hypertrophy or local giantism, and also from inflammatory swellings, which usually develop under the influence of a definite cause, have a natural termination, and tend to disappear when the cause ceases to act.

The _etiology of tumours_ is imperfectly understood. Various factors, acting either singly or in combination, may be concerned in their development. Certain tumours, for example, are the result of some congenital malformation of the particular tissue from which they take origin. This would appear to be the case in many tumours of blood vessels (angioma), of cartilage (chondroma), of bone (osteoma), and of secreting gland tissue (adenoma). The theory that tumours originate from foetal residues or "rests," is associated with the name of Cohnheim. These rests are supposed to be undifferentiated embryonic cells which remain embedded amongst fully formed tissue elements, and lie dormant until they are excited into active growth and give rise to a tumour. This mode of origin is illustrated by the development of dermoids from sequestrated portions of epidermis.

Among the local factors concerned in the development of tumours, reference must be made to the influence of irritation. This is probably an important agent in the causation of many of the tumours met with in the skin and in mucous membranes--for example, cancer of the skin, of the lip, and of the tongue. The part played by injury is doubtful. It not infrequently happens that the development of a tumour is preceded by an injury of the part in which it grows, but it does not necessarily follow that the injury and the tumour are related as cause and effect. It is possible that an injury may stimulate into active growth undifferentiated tissue elements or "rests," and so determine the growth of a tumour, or that it may alter the characters of a tumour which already exists, causing it to grow more rapidly.

The popular belief that there is some constitutional peculiarity concerned in the causation of tumours is largely based on the fact that certain forms of new growth--for example, cancer--are known to occur with undue frequency in certain families. The same influence is more striking in the case of certain innocent tumours--particularly multiple osteomas and lipomas--which are hereditary in the same sense as supernumerary or webbed fingers, and appear in members of the same family through several generations.

INNOCENT AND MALIGNANT TUMOURS

For clinical purposes, tumours are arbitrarily divided into two classes--the innocent and the malignant. The outstanding difference between them is, that while the evil effects of innocent tumours are entirely local and depend for their severity on the environment of the growth, malignant tumours wherever situated, in addition to producing similar local effects, injure the general health and ultimately cause death.

_Innocent_, benign, or simple tumours present a close structural resemblance to the normal tissues of the body. They grow slowly, and are usually definitely circumscribed by a fibrous capsule, from which they are easily enucleated, and they do not tend to recur after removal. In their growth they merely push aside and compress adjacent parts, and they present no tendency to ulcerate and bleed unless the overlying skin or mucous membrane is injured. Although usually solitary, some are multiple from the outset--for example, fatty, fibrous, and bony tumours, warts, and fibroid tumours of the uterus. They produce no constitutional disturbance. They only threaten life when growing in the vicinity of vital organs, and then only in virtue of their situation--for example, death may result from an innocent tumour in the air-passage causing suffocation, in the intestine causing obstruction of the bowels, or in the vertebral canal causing pressure on the spinal medulla.

_Malignant tumours_ usually show a marked departure from the structure and arrangement of the normal tissues of the body. Although the cells of which they are composed are derived from normal tissue cells, they tend to take on a lower, more vegetative form; they may be regarded as parasites living at the expense of the organism, multiplying indefinitely and destroying everything with which they come in contact.

Malignant tumours grow more rapidly than innocent tumours, and tend to infiltrate their surroundings by sending out prolongations or offshoots; they are therefore liable to recur after an operation which is restricted to the removal of the main tumour. They are not encapsulated, although they may appear to be circumscribed by condensation of the surrounding tissues; they are rarely multiple at the outset, but show a marked tendency to spread to other parts of the body. Fragments of the parent tumour may become separated and be carried off in the lymph or blood-stream and deposited in other parts of the body, where they give rise to secondary growths. Malignant tumours tend to invade and destroy the overlying skin or mucous membrane, and thus give rise to bleeding ulcers; if the tumour tissue protrudes through the gap in the skin, it is said to _fungate_. In course of time they give rise to a condition of ill-health or _cachexia_, the patient becoming pale, sallow, feverish, and emaciated, probably as a result of chronic poisoning from the absorption of toxic products from the tumour. They ultimately destroy life, it may be by their local effects, such as ulceration and haemorrhage, by favouring the entrance of septic infection, by interfering with the function of organs which are essential to life, by cachexia, or by a combination of these effects.

The situation of a malignant tumour exercises considerable influence on the rapidity, as well as on the mode, in which it causes death. Some cancers, such as that known as "rodent," show malignant features which are entirely local, while others, such as melanotic cancer, exhibit a malignancy characterised by rapid generalisation of growths throughout the body. Tumours that are structurally alike may show variations in malignancy, according to their situation and to the age of the patient, as well as to other factors which are as yet unknown.

In attempting to arrive at a conclusion as to the innocence or malignancy of any tumour, too much reliance must not be placed on its histological features; its situation, rate of growth, and other clinical features must also be taken into consideration. It cannot be too emphatically stated that there is no hard-and-fast line between innocent and malignant growths; there is an indefinite transition from one to the other. The possibility of the transformation of a benign into a malignant tumour must be admitted. Such a transformation implies a change in the structure of the growth, and has been observed especially in fibrous and cartilaginous tumours, in tumours of the thyreoid gland, and in uterine fibroids. The alteration in character may take place under the influence of injury, prolonged or repeated irritation, incomplete removal of the benign tumour by operation, or the altered physiological conditions of the tissues which attend upon advancing years.

After a tumour has been removed by operation it should as a routine measure be subjected to microscopical examination; the results are often instructive and sometimes other than what was expected.

1. Varieties of Tumours.#--In the following description, tumours are

classified on an anatomical basis, taking in order first the connective-tissue group and subsequently those that originate in epithelium.

INNOCENT CONNECTIVE-TISSUE TUMOURS

1. Lipoma.#--A lipoma is composed of fat resembling that normally present

in the body. The commonest variety is the _subcutaneous lipoma_, which grows from the subcutaneous fat, and forms a soft, irregularly lobulated tumour (Fig. 45). The fat is arranged in lobules separated by connective-tissue septa, which are continuous with the capsule surrounding the tumour and with the overlying skin, which becomes dimpled or puckered when an attempt is made to pinch it up. As the fat is almost fluid at the body temperature, fluctuation can usually be detected. These tumours vary greatly in size, occur at all ages, grow slowly, and, while generally solitary, are sometimes multiple. They are most commonly met with on the shoulder, buttock, or back. In certain situations, such as the thigh and perineum, they tend to become pedunculated (Fig. 46).

A fatty tumour is to be diagnosed from a cold abscess and from a cyst. The distinguishing features of the lipoma are the tacking down and dimpling of the overlying skin, the lobulation of the tumour, which is recognised when it is pressed upon with the flat of the hand, and, more reliable than either of these, the mobility, the tumour slipping away when pressed upon at its margin.

[Illustration: FIG. 45.--Subcutaneous Lipoma showing lobulation.]

The prognosis is more favourable than in any other tumour as it never changes its characters; the only reasons for its removal by operation are its unsightliness and its probable increase in size in the course of years. The operation consists in dividing the skin and capsule over the tumour and shelling it out. Care must be taken that none of the outlying lobules are left behind. If the overlying skin is damaged or closely adherent, it should be removed along with the tumour.

[Illustration: FIG. 46.--Pedunculated Lipoma of Buttock of forty years' duration in a woman aet. 68.]

_Multiple subcutaneous lipomas_ are frequently symmetrical, and in a certain group of cases, met with chiefly in women, pain is a prominent symptom, hence the term _adiposis dolorosa_ (Dercum). These multiple tumours show little or no tendency to increase in size, and the pain which attends their development does not persist.

In the neck, axilla, and pubes a diffuse overgrowth of the subcutaneous fat is sometimes met with, forming symmetrical tumour-like masses, known as _diffuse lipoma_. As this is not, strictly speaking, a tumour, the term _diffuse lipomatosis_ is to be preferred. A similar condition was described by Jonathan Hutchinson as being met with in the domestic animals. If causing disfigurement, the mass of fat may be removed by operation.

[Illustration: FIG. 47.--Diffuse Lipomatosis of Neck.]

_Lipoma in other Situations._--The _periosteal lipoma_ is usually congenital, and is most often met with in the hand; it forms a projecting lobulated tumour, which, when situated in the palm, resembles an angioma or a lymphangioma. The _subserous lipoma_ arises from the extra-peritoneal fat in the posterior abdominal wall, in which case it tends to grow forwards between the layers of the mesentery and to give rise to an abdominal tumour; or it may grow from the extra-peritoneal fat in the anterior abdominal wall and protrude from one of the hernial openings or through an abnormal opening in the parietes, constituting a _fatty hernia_. A _subsynovial lipoma_ grows from the fat surrounding the synovial membrane of a joint, and projects into its interior, giving rise to the symptoms of loose body. Lipomas are also met with growing from the adipose connective tissue _between or in the substance of muscles_, and, when situated beneath the deep fascia, such as the fascia lata of the thigh, the characteristic signs are obscured and a differential diagnosis is difficult. It may be differentiated from a cold abscess by puncture with an exploring needle.

[Illustration: FIG. 48.--Zanthoma of Hands in a girl aet. 14, showing multiple subcutaneous tumours (cf. Fig. 49).

(Sir H. J. Stiles' case.)]

1. Zanthoma# is a rare but interesting form of tumour, composed of a

fibrous and fatty tissue, containing a granular orange-yellow pigment, resembling that of the corpus luteum. It originates in the corium and presents two clinical varieties. In the first of these, it occurs in the form of raised yellow patches, usually in the skin of the eyelids of persons after middle life, and in many instances is associated with chronic jaundice; the patches are often symmetrical, and as they increase in size they tend to fuse with another.

The second form occurs in children and adolescents; it may affect several generations of the same family, and is often multiple, there being a combination of thickened yellow patches of skin and projecting tumours, some of which may attain a considerable size (Figs. 48 and 49). On section, the tumour tissue presents a brilliant orange or saffron colour.

There is no indication for removing the tumours unless for the deformity which they cause; exposure to the X-rays is to be preferred to operation.

[Illustration: FIG. 49.--Zanthoma showing Subcutaneous Tumours on Buttocks. From same patient as Fig. 48.]

1. Chondroma.#--A chondroma is mainly composed of cartilage. Processes of

vascular connective tissue pass in between the nodules of cartilage composing the tumour from the fibrous capsule which surrounds it. On section it is of a greyish-blue colour and semi-translucent. The tumour is firm and elastic in consistence, but certain portions may be densely hard from calcification or ossification, while other portions may be soft and fluctuating as a result of myxomatous degeneration and liquefaction. These tumours grow slowly and painlessly, and may surround nerves and arteries without injuring them. They may cause a deep hollow in the bone from which they originate. All intermediate forms between the innocent chondroma and the malignant chondro-sarcoma are met with. Chondroma may occur in a multiple form, especially in relation to the phalanges and metacarpal bones. When growing in the interior of a bone it causes a spindle-shaped enlargement of the shaft, which in the case of a phalanx or metacarpal bone may resemble the dactylitis resulting from tubercle or syphilis. A chondroma appears as a clear area in a skiagram.

A _skiagram_ of a bone in which there is a chondroma shows a clear rounded area in the position of the tumour, which must be differentiated from similar clear areas due to other kinds of tumour, especially the myeloma; when it has undergone calcification or ossification, it gives a shadow as dark as bone.

[Illustration: FIG. 50.--Chondroma growing from infraspinous fossa of Scapula.]

[Illustration: FIG. 51.--Chondroma of Metacarpal Bone of Thumb.]

_Treatment._--In view of the unstable quality of the chondroma, especially of its liability to become malignant, it should be removed as soon as it is recognised. In those projecting from the surface of a bone, both the tumour and its capsule should be removed. If in the interior, a sufficient amount of the cortex should be removed to allow of the tumour being scraped out, and care must be taken that no nodules of cartilage are left behind. In multiple chondromas of the hand, when the fingers are crippled and useless, exposure to the X-rays should be given a trial, and in extreme cases the question of amputation may have to be considered. When a cartilaginous tumour takes on active growth, it must be treated as malignant.

The chondromas that are met with at the ends of the long bones in children and young adults form a group by themselves. They are usually related to the epiphysial cartilage, and it was suggested by Virchow that they take origin from islands of cartilage which have not been used up in the process of ossification. They are believed to occur more frequently in those who have suffered from rickets. They have no malignant tendencies and tend to undergo ossification concurrently with the epiphysial cartilage from which they take origin, and constitute what are known as _cartilaginous exostoses_. These are sometimes met with in a multiple form, and may occur in several generations of the same family. They are considered in greater detail in the chapter dealing with tumours of bone.

Minute nodules of cartilage sometimes form in the synovial membrane of joints and lining of tendon sheaths and bursae: they tend to become detached from the membrane and constitute loose bodies; they also undergo a variable amount of calcification and ossification, so as to be visible in skiagrams. They are further considered with loose bodies in joints.

Cartilaginous tumours in the parotid, submaxillary gland, and testicle belong to a class of "mixed tumours" that will be referred to later.

1. Osteoma.#--The true osteoma is composed of bony tissue, and originates

from the skeleton. Two varieties are recognised--the spongy or cancellous, and the ivory or compact. The _spongy_ or _cancellous osteoma_ is really an ossified chondroma, and is met with at the ends of the long bones (Fig. 52). From the fact that it projects from the surface of the bone it is often spoken of as an _exostosis_. It grows slowly, and rarely causes any discomfort unless it presses upon a nerve-trunk or upon a bursa which has developed over it. The Rontgen rays show a dark shadow corresponding to the ossified portion of the tumour, and continuous with that of the bone from which it is growing (Fig. 138). Operative interference is only indicated when the tumour is giving rise to inconvenience. It is then removed, its base or neck being divided by means of the chisel. The multiple variety of osteoma is considered with the diseases of bone.

The bony outgrowth from the terminal phalanx of the great toe--known as the _subungual exostosis_--is described and figured on p. 404. Bony projections or "spurs" sometimes occur on the under surface of the calcaneus, and, projecting downwards and forwards from the greater process, cause pain on putting the heel to the ground.

[Illustration: FIG. 52.--Cancellous Osteoma of lower end of Femur.]

The _ivory_ or _compact osteoma_ is composed of dense bone, and usually grows from the skull. It is generally sessile and solitary, and may grow into the interior of the skull, into the frontal sinus, into the cavity of the orbit or nose, or may fill up the external auditory meatus, causing most unsightly deformity and interference with sight, breathing, and hearing.

Bony formations occur in _muscles and tendons_, especially at their points of attachment to the skeleton, and are known as false exostoses; they are described with the diseases of muscles.

1. Odontoma.#--An odontoma is composed of dental tissues in varying

proportions and different degrees of development, arising from tooth-germs or from teeth still in process of growth (Bland Sutton). Odontomas resemble teeth in so far that during their development they remain hidden below the mucous membrane and give no evidence of their existence. There then succeeds, usually between the twentieth and twenty-fifth years, an eruptive stage, which is often attended with suppuration, and this may be the means of drawing attention to the tumour. Following Bland Sutton, several varieties of odontoma may be distinguished according to the part of the tooth-germ concerned in their formation.

The _epithelial odontoma_ is derived from persistent portions of the epithelium of the enamel organ, and constitutes a multilocular cystic tumour which is chiefly met with in the mandible. The cystic spaces of the tumour contain a brownish glairy fluid. These tumours have been described by Eve under the name of multilocular cystic epithelial tumours of the jaw.

The _follicular odontoma_, also known as a _dentigerous cyst_, is derived from the distension of a tooth follicle. It constitutes a cyst containing a viscid fluid, and an imperfectly formed tooth is often found embedded in its wall. The cyst usually forms in relation to one of the permanent molars, and may attain considerable dimensions.

The _fibrous odontoma_ is the result of an overgrowth of fibrous tissue surrounding the tooth sac, which encapsulates the tooth and prevents its eruption. The thickened tooth sac is usually mistaken for a fibrous tumour, until, after removal, the tooth is recognised in its interior.

_Composite Odontoma._--This is a convenient term to apply to certain hard dental tumours which are met with in the jaws, and consist of enamel, dentine, and cement. The tumour is to be regarded as being derived from an abnormal growth of all the elements of a tooth germ, or of two or more tooth germs, indiscriminately fused with one another. It may appear in childhood, and form a smooth unyielding tumour, often of considerable size, replacing the corresponding permanent tooth. It may cause a purulent discharge, and in some cases it has been extruded after sloughing of the overlying soft parts. Many examples of this variety of odontoma, growing in the nasal cavity or in the maxillary sinus, have been erroneously regarded as osteomas even after removal.

On section, the tumour is usually laminated, and is seen to consist mainly of dentine with a partial covering of enamel and cement.

_Diagnosis._--Odontomas are often only diagnosed after removal. When attended with suppuration, the condition has been mistaken for disease of the jaw. Fibrous odontomas have been mistaken for sarcoma, and portions of the maxilla removed unnecessarily. Any circumscribed tumour of the jaw, particularly when met with in a young adult, should suggest the possibility of an odontoma. Skiagrams often give useful information both for diagnosis and for treatment.

_Treatment._--The solid varieties of odontoma can usually be shelled out after dividing the overlying soft parts. In the follicular variety, it is usually sufficient to excise a portion of the wall, scrape out the interior, and remove any tooth that may be present. The cavity is then packed and allowed to heal from the bottom.

1. Fibroma.#--A fibroma is a tumour composed of fibrous connective tissue.

A distinction may be made between the _soft fibroma_, which is comparatively rich in cells and blood vessels, and in which the fibres are arranged loosely; and the _hard fibroma_, which is composed of closely packed bundles of fibres often arranged in a concentric fashion around the blood vessels. The cut surface of the soft fibroma presents a pinkish-white, fleshy appearance, resembling the slowly growing forms of sarcoma; that of a hard fibroma presents a dry, glistening appearance, aptly compared to watered silk. The soft variety grows much more rapidly than the hard. In certain fibromas--in those, for example, which grow from the periosteum of the base of the skull and project into the naso-pharynx--the blood vessels are dilated into sinuses and have no proper sheaths; they therefore tend to remain open when divided, and to bleed excessively. Transition forms between soft fibroma and sarcoma are met with, so that in operating for their removal it is safer to take away the capsule along with the tumour, and the patient should be kept under observation in view of the risk of recurrence.

The skin--especially the skin of the buttock--is one of the favourite seats of fibroma, and it may occur in a multiple form. It is met with also in the subcutaneous and intermuscular cellular tissue, and in the abdominal wall, where it sometimes attains considerable dimensions. Various forms of fibroma are met with in the mamma and are described with diseases of that organ. The fibrous overgrowths in the skin, known as _keloid_ and _molluscum fibrosum_, and those met with in the _sheaths of nerves_, are described elsewhere. Fibroid tumours of the uterus are described with myoma.

_Diffuse fibroma_ or _Fibromatosis_, analogous to lipomatosis, is met with in the connective tissue of the skin and sheaths of nerves, and constitutes one form of neuro-fibromatosis; a similar change is also met with in the stomach and colon.

1. Myxoma.#--A myxoma is composed of tissue of a soft gelatinous,

semifluid consistence. The pure myxoma is extremely rare, and clinically resembles the lipoma. Myxomatous tissue is, however, frequently found in other connective-tissue tumours as a result of degeneration, for example, in cartilaginous tumours and in sarcomas. Myxomatous tissue is also a prominent constituent of the "innocent parotid tumour." Mucous polypus of the nose, which is often described as a myxoma, is merely a pendulous process of oedematous mucous membrane.

[Illustration: FIG. 53.--Myeloma of Shaft of Humerus, causing pathological fracture. (Mr. J. W. Struthers' case.)

(The unusual site of the tumour is to be noted.)]

1. Myeloma.#--A myeloma is composed of large multinuclear giant cells

surrounded by round and spindle cells. The cut surface of the tumour presents a deep red or maroon colour. While occasionally met with in tendon sheaths and bursae, and is then of an orange-yellow colour, the myeloma occurs most frequently in the cancellous tissue at the ends of the long bones, its favourite site being the upper end of the tibia. Although formerly classified as a sarcoma, it is the exception for it to present malignant features, and it can usually be extirpated by local measures without fear of recurrence. The diagnosis, X-ray appearances, and the method of removal are considered with the diseases of bone. Sometimes the myeloma is met with in multiple form in the skeleton, in association with an unusual form of protein in the urine (Bence Jones).

1. Myoma.#--A myoma is composed of non-striped muscle fibres. A pure myoma

is very rare, and is met with in organs possessed of non-striped muscle, such as the stomach, intestine, urinary bladder, and prostate. In the uterus, which is the most common situation, these tumours contain a considerable admixture of fibrous tissue, and are known as _fibroids_ or _fibro-myomas_. They present on section a fasciculated appearance, which may resemble that of a section of balls of cotton (Fig. 54). They are encapsulated and vascular, frequently attain a large size, and may be single or multiple. While they may occasion neither inconvenience nor suffering, they frequently give rise to profuse haemorrhage from the uterus, and may cause serious symptoms by pressing injuriously on the ureters or the intestine, or by complicating pregnancy and parturition.

The #Rhabdomyoma# is an extremely rare form of tumour, met with in the kidney, uterus, and testicle. It contains striped muscle fibres, and is supposed to originate from a residue of muscular tissue which has become sequestrated during development.

[Illustration: FIG. 54.--Fibro-myoma of Uterus.

(Anatomical Museum, University of Edinburgh.)]

1. Glioma.#--A glioma is a tumour composed of neuroglia. It is met with

exclusively in the central nervous system, retina, and optic nerve. It is a slowly growing, soft, ill-defined tumour, which displaces the adjacent nerve centres and nerve tracts, and is liable to become the seat of haemorrhage and thus to give rise to pressure symptoms resembling apoplexy. The glioma of the retina tends to grow into the vitreous humour and to perforate the globe. It is usually of the nature of a glio-sarcoma and is highly malignant.

1. Endotheliomas# take origin from the endothelium of lymph vessels and

blood vessels, and serous cavities. They show great variation in type, partly because of the number of different kinds of endothelium from which they are derived, and partly because the new connective tissue which is formed is liable to undergo transformation into other tissues. They may be soft or hard, solid or cystic, diffuse or circumscribed; they grow very slowly, and are almost always innocent, although recurrence has been occasionally observed. Cases of multiple endotheliomata of the skin have recently been described by Wise.

_Angioma_, _lymphangioma_, and _neuroma_ are described with the disease of the individual tissues.

MALIGNANT CONNECTIVE-TISSUE TUMOURS--SARCOMA

The term sarcoma is applied to any connective-tissue tumour which exhibits malignant characters. The essential structural feature is the predominance of the cellular elements over the intercellular substance or stroma, in which respect a sarcoma resembles the connective tissue of the embryo. The typical sarcoma consists chiefly of immature or embryonic connective tissue. It most frequently originates from fascia, intermuscular connective tissue, periosteum, bone-marrow, and skin, and forms a rounded or nodulated tumour which appears to be encapsulated, but the capsule merely consists of the condensed surrounding tissues, and usually contains sarcomatous elements. The consistence of the tumour depends on the nature and amount of the stroma, and on the presence of degenerative changes. The softer medullary forms are composed almost exclusively of cells; while the harder forms--such as the fibro-, chondro-, and osteo-sarcoma--are provided with an abundant stroma and are relatively poor in cells. Degenerative changes may produce areas of softening or liquefaction which result in the formation of cystic cavities in the interior of the tumour. The colour depends on the amount of blood in the tumour, and on the presence of the products of degeneration.

The blood vessels are usually represented by mere chinks or spaces between the cells. This peculiarity accounts for the facility with which haemorrhage takes place into the substance of the tumour, the persistence of the bleeding when it is incised or ulcerates through the skin, and the readiness with which the sarcomatous cells are carried off and infect distant parts through the blood-stream. Sarcomas are devoid of lymphatics, and unless originating in lymphatic structures--for example, in the tonsil--they rarely infect the lymph glands. Minute portions of the tumour grow into the small veins, and, becoming detached, are transported by the blood-current to distant organs, where they are arrested in the capillaries and give rise to secondary growths. These are most frequently situated in the lungs, except when the primary growth lies within the territory of the portal circulation, in which case they occur in the liver. The secondary growths closely resemble the parent tumour. Sarcoma may invade an adjacent vein on such a scale that if the invading portion becomes detached it may constitute a dangerous embolus. This may be observed in sarcoma of the kidney, the growth taking place along the renal vein until it projects into the vena cava.

[Illustration: FIG. 55.--Recurrent Sarcoma of Sciatic Nerve in a woman aet. 27. Recurrence twenty months after removal of primary growth.]

In its growth, a sarcoma compresses and destroys neighbouring parts, surrounds vessels and nerves, and may lead to destruction of the skin, either by invading it, or more commonly by causing sloughing from pressure. Inflammatory and suppurative changes may take place as a result of pyogenic infection following upon sloughing of the overlying skin or upon an exploratory incision. Once the skin is broken the tumour fungates through the opening. Sarcomas vary in malignancy, especially as regards rapidity of growth and capacity for dissemination. Certain of them, such as the so-called "recurrent fibroid of Paget," grow comparatively slowly, and are only malignant in the sense that they tend to recur locally after removal; others--especially the more cellular ones--grow with extreme rapidity, and are early disseminated throughout the body, resembling in these respects the most malignant forms of cancer. They are usually solitary in the first instance, although primary multiple growths are occasionally met with in the skin and in the bones.

Many varieties of sarcoma are recognised, according to its structural peculiarities. Thus, in virtue of the size and character of the cells, we have the _small round-celled_ and the _large round-celled_ sarcoma, the _small_ and the _large spindle-celled_, the _giant-celled_ and the _mixed-celled_ sarcoma. The _lympho-sarcoma_ presents a structure similar to that of lymph-follicular tissue, and the _alveolar sarcoma_ an arrangement of cells in alveoli resembling that seen in cancers. When there is a considerable amount of intercellular fibrous tissue, the tumour is called a _fibro-sarcoma_.

[Illustration: FIG. 56.--Fungating Sarcoma of Arm.

(Dr. J. M'Watt's case.)]

The term _lymphangio-sarcoma_ is applied when the cells of the tumour are derived from the endothelium of lymph spaces and vessels. The _angio-sarcomas_ are those in which blood vessels form a prominent element in the structure of the tumour. They are sometimes derived from innocent angiomas, and they may be so vascular as to pulsate and on auscultation yield a blowing murmur like an aneurysm. The _glio-sarcoma_, _myxo-sarcoma_, _chondro-sarcoma_, and _myo-sarcoma_ are mixed forms which usually develop in pre-existing innocent tumours. The _osteo-sarcoma_ is characterised by the formation in the tumour of bone, the medullary spaces being occupied by sarcomatous cells in place of marrow. The _osteoid sarcoma_ is characterised by the formation of a tissue resembling bone but deficient in lime salts, and the _petrifying sarcoma_ by the formation of calcified areas in the stroma. These varieties, although met with chiefly in the bones, may occur in soft tissues such as muscle, and in such organs as the mamma. The pigmented varieties include the _chloroma_, which is of a light-green colour, and the _melanotic sarcoma_, which is brown or black. The _psammoma_ is a sarcoma containing a material resembling sand; it is chiefly met with in the membranes of the brain. The _chordoma_ is a rare form of tumour originating from the remains of the notochord in the region of the spheno-occipital synchondrosis or in the sacro-coccygeal region.

_Diagnosis of Sarcoma._--A sarcoma is to be differentiated from an inflammatory swelling such as results from tubercle, actinomycosis, or syphilis, from an innocent tumour, and from a cancer. The points on which the diagnosis is founded are discussed with the different tissues and organs.

_Treatment._--The removal of the tumour by operation is the most reliable method of treatment; in order to be successful it must be undertaken before dissemination has taken place, and a considerable area of healthy tissue beyond the apparent margin of the growth must be removed, and in tumours near the surface of the body, the overlying skin also.

In order to prevent recurrence, a tube of _radium_, to which a silk thread is attached, is inserted into the space from which the tumour was removed; the thread is brought out at the drain-opening, and at the end of a week or ten days the tube of radium is removed by pulling on the thread. Radium causes a reaction in the tissues attended with exudation from the vessels, for the escape of which provision must be made. If radium is not available, the affected area is repeatedly exposed to the action of the _X-rays_ as soon as the wound has healed. The employment of these measures has diminished to a remarkable degree the recurrence of sarcoma after operation.

It will readily be understood that the less thoroughly or radically the growth has been removed, the more do we depend upon radium or the X-rays for bringing about a permanent cure, and that in advanced cases of sarcoma and in cases in which, on account of their anatomical situation, removal by operation is necessarily incomplete, the prospect of cure is still more dependent on the use of radium or of the X-rays. Finally, there are cases in which removal by operation is impossible, the so-called _inoperable sarcoma_; a tube of radium, to which a silk thread is attached, is inserted into the substance of the tumour, either through an opening made by a large trocar, or, when necessary, by open dissection. A second tube of radium is placed upon the skin over the tumour and is secured there by a stitch or by a strip of plaster, thus securing a cross-fire action of the radium rays, both from within and without, as this is found to be much more efficacious in destroying or inhibiting the cellular elements of the growth. The tubes of radium are left _in situ_ for from eight to fourteen days, according to the power of the radium employed, but are moved about every second day or so in order that every part of the tumour may be efficiently radiated. If the tumour shrinks in size after the use of radium and becomes operable, it should be removed before time is given it to resume its growth. It will depend upon the subsequent course of the disease, whether or not a second, or it may be even a third, application of radium will be required.

Where neither radium nor X-rays is available or applicable, recourse may be had to the injection of Coley's fluid, a preparation containing the mixed toxins of the streptococcus of erysipelas and the bacillus prodigiosus; or of selenium.

EPITHELIAL TUMOURS

An excessive and erratic growth of epithelium is the essential and distinguishing feature of these tumours. The innocent forms are the papilloma and the adenoma; the malignant, the carcinoma or cancer.

1. Papilloma.#--A papilloma is a tumour which projects from a cutaneous or

mucous surface, and consists of a central axis of vascular fibrous tissue with a covering of epithelium resembling that of the surface from which the tumour grows. In the papillomas of the skin--commonly known as _warts_--the covering consists of epidermis; in those growing from mucous surfaces it consists of the epithelium covering the mucous membrane. When the surface epithelium projects as filiform processes, the tumour is called a _villous papilloma_, the best-known example of which is met with in the urinary bladder. Papillomatous growths are also met with in the larynx, in the ducts of the breast, and in the interior of certain cystic tumours of the breast and of the ovary. Although papillomas are primarily innocent, they may become the starting-point of cancer, especially in persons past middle life and if the papilloma has been subjected to irritation and has ulcerated. The clinical features and treatment of the various forms of papilloma are considered with the individual tissues and organs.

1. Adenoma.#--An adenoma is a tumour constructed on the type of, and

growing in connection with, a secreting gland. In the substance of such glands as the mamma, parotid, thyreoid, and prostate, adenomas are met with as encapsulated tumours. When they originate from the glands of the skin or of a mucous membrane, they tend to project from the surface, and form pedunculated tumours or polypi.

Adenomas may be single or multiple, and they vary greatly in size. The tumour is seldom composed entirely of gland tissue; it usually contains a considerable proportion of fibrous tissue, and is then called a _fibro-adenoma_. When it contains myxomatous tissue it is called a _myxo-adenoma_, and when the gland spaces of the tumour become distended with accumulated secretion, a _cystic adenoma_, the best examples of which are met with in the mamma and ovary. A characteristic feature of the cystic variety is the tendency the tumour tissue exhibits to project into the interior of the cysts, constituting what are known as _intracystic growths_. They are essentially innocent, but intracystic growths, especially in the mamma of women over fifty, should be regarded with suspicion and therefore should be removed on radical lines. Transition forms between adenoma and carcinoma are also met with in the rectum and large intestine, and these should be treated on the same lines as cancer.

CARCINOMA OR CANCER

A cancer is a malignant tumour which originates in epithelium. The cancer cells are derived by proliferation from already existing epithelium, and they invade the sub-epithelial connective tissue in the form of simple or branching columns. These columns are enclosed in spaces--termed alveoli--which are probably dilated lymph spaces, and which communicate freely with the lymph vessels. The cells composing the columns and filling the alveoli vary with the character of the epithelium in which the cancer originates. The malignancy of cancer depends on the tendency which the epithelium has of invading the tissues in its neighbourhood, and on the capacity of the cells, when transported elsewhere by the lymph or blood-stream, of giving rise to secondary growths.

Cancer may arise on any surface covered by epithelium or in any of the secreting glands of the body, but it is much more common in some situations than in others. It is frequently met with, for example, in the skin, in the stomach and large intestine, in the breast, the uterus, and the external genitals; less frequently in the gall-bladder, larynx, thyreoid, prostate, and urinary bladder.

Tissues appear to be most liable to cancer when, having attained maturity, they enter upon the phase of decadence or involution, and this phase is reached by different tissues at different periods. It is not so much, therefore, the age of the person in whom it occurs, as the age of the tissue in which it arises, that determines the maximum incidence of cancer. Cancer of the stomach appears and attains a maximum frequency earlier than cancer of the skin; cancer of the uterus and mamma is more frequent towards the decline of reproductive activity than in the later years of life; rectal cancer is not infrequently met with during the second and third decades. There is evidence that the irritation caused by alcohol and tobacco plays a part in the causation of cancer, in the fact that a large proportion of those who become the subjects of cancer of the mouth are excessive drinkers and smokers.

A cancer may appear as a papillary growth on a mucous or a skin surface, as a nodule in the substance of an organ, or as a diffuse thickening of a tubular organ such as the stomach or intestine. The absence of definition in cancerous tumours explains the difficulty of completely removing them by surgical measures, and has led to the practice of complete extirpation of cancerous organs wherever this is possible. The boundaries of the affected organ, moreover, are frequently transgressed by the disease, and the epithelial infiltration implicates the surrounding parts. In cancer of the breast, for example, the disease often extends to the adjacent skin, fat, and muscle; in cancer of the lip or tongue, to the mandible; in cancer of the uterus or intestine, to the investing peritoneum.

In addition to its tendency to infiltrate adjacent tissues and organs, cancer is also liable to give rise to _secondary growths_. These are most often met with in the nearest lymph glands; those in the neck, for example, becoming infected from cancer of the lip, tongue, or throat; those in the axilla, from cancer of the breast; those along the curvatures of the stomach, from cancer of the pylorus; and those in the groin, from cancer of the external genitals. In lymph vessels the cancer cells may merely accumulate so as to fill the lumen and form indurated cords, or they may proliferate and give rise to secondary nodules along the course of the vessels. When the lymphatic network in the skin is diffusely infected, the appearance is either that of a multitude of secondary nodules or of a diffuse thickening, so that the skin comes to resemble coarse leather. On the wall of the chest this condition is known as _cancer en cuirasse_. Although the cancer cells constantly attack the walls of the adjacent veins and spread into their interior at a comparatively early period, secondary growths due to dissemination by the blood-stream rarely show themselves clinically until late in the course of the disease. It is probable that many of the cancer cells which are carried away in the blood or lymph stream undergo necrosis and fail to give rise to secondary growths. Secondary growths present a faithful reproduction of the structure of the primary tumour. Apart from the lymph glands, the chief seats of secondary growths are the liver, lungs, serous membranes, and bone marrow.

It is generally believed that the secondary growths in cancer that develop at a distance from the primary tumour, those, for example, in the medullary canal of the femur or in the diploe of the skull occurring in advanced cases of cancer of the breast, are the result of dissemination of cancer cells by way of the blood-stream and are to be regarded as emboli. Sampson Handley disagrees with this view; he believes that the dissemination is accomplished in a more subtle way, namely, by the actual growth of cancer cells along the finer vessels of the lymph plexuses that ramify in the deep fascia, a method of spread which he calls _permeation_. It is maintained also that permeation occurs as readily against the lymph stream as with it. He compares the spread of cancer to that of an invisible annular ringworm. The growing edge extends in a wider and wider circle, within which a healing process may occur, so that the area of permeation is a ring, rather than a disc. Healing occurs by a process of "peri-lymphatic fibrosis," but as the natural process of healing may fail at isolated points, nodules of cancer appear, which, although apparently separate from the primary growth, have developed in continuity with it, peri-lymphatic fibrosis having destroyed the cancer chain connecting the nodule with the primary growth. This centrifugal spread of cancer is clearly seen in the distribution of the subcutaneous secondary nodules so frequently met with in the late stages of mammary cancer. The area within which the secondary nodules occur is a circle of continually increasing diameter with the primary growth in the centre.

In the rare cases in which the skin of the greater part of the body is affected, the nodules rarely appear below the level of the deltoid or the middle third of the thigh, the patient dying before the spread can reach the distal portions of the limbs.

Handley argues against the embolic origin of the metastases in the bones because of the rarity of these in the bones of the distal parts of the limbs, because of the fact that secondary cancer of the femur nearly always commences in the upper third of the shaft, which harmonises with the intimate connection of the deep fascia with the periosteum over the great trochanter, thus favouring invasion of the bone marrow when permeation has spread thus far. He claims support for the permeation theory from the fact that the humerus is rarely involved below the insertion of the deltoid, and that spontaneous fracture of the femur is three times more common on the side on which the breast cancer is situated.

The tumour tissue may undergo necrosis, and when the overlying skin or mucous membrane gives way an ulcer is formed. The margins of a _cancerous ulcer_ (Fig. 57) are made up of tumour tissue which has not broken down. Usually they are irregular, nodularly thickened or indurated; sometimes they are raised and crater-like. The floor of the ulcer is smooth and glazed, or occupied by necrosed tissue, and the discharge is watery and blood-stained, and as a result of putrefactive changes may become offensive. Haemorrhage is rarely a prominent feature, but discharge of blood may constitute a symptom of considerable diagnostic importance in cancer of internal organs such as the rectum, the bladder, or the uterus.

[Illustration: FIG. 57.--Carcinoma of Breast with Cancerous Ulcer.]

_The Contagiousness of Cancer._--A limited number of cases are on record in which a cancer appears to have been transferred by contact, as from the lower to the upper lip, from one labium majus to the other, from the tongue to the cheek, and from one vocal cord to the other; these being all examples of cancer involving surfaces which are constantly or frequently in contact. The transference of cancer from one human being to another, whether by accident, as in the case of a surgeon wounding his finger while operating for cancer, or by the deliberate introduction of a portion of cancerous tumour into the tissues, has never been known to occur. It is by no means infrequent, however, that when recurrence takes place after an operation for the removal of cancer, the recurrent nodules make their appearance in the main scar or in the scars of stitches in its neighbourhood. In the lower animals the grafting of cancer only succeeds in animals of the same species; for example, a cancer taken from a mouse will not grow in the tissues of a rat, but only in a mouse of the same variety as that from which the graft was taken.

While cancer cannot be regarded as either contagious or infectious, it is important to bear in mind the possibility of infection of a wound with cancer when operating for the disease. A cancer should not be cut into unless this is essential for purposes of diagnosis, and the wound made for exploration should be tightly closed by stitches before the curative operation is proceeded with; the instruments used for the exploration must not be used again until they have been boiled. The greatest care should be taken that a cancer which has softened or broken down is not opened into during the operation.

Investigations regarding the cause of cancer have been prosecuted with great energy during recent years, but as yet without positive result. It is recognised that there are a number of conditions which favour the development of cancer, such as prolonged irritation, and a considerable number of cases have been recorded in which cancer of the skin of the hands has followed prolonged and repeated exposure to the Rontgen rays.

_The Alleged Increase of Cancer._--Regarding the alleged increase of cancer, it may be pointed out that it is impossible to ascertain how much of the apparent increase is due to more accurate diagnosis and improved registration. It is probable also that some increase has taken place in consequence of the increased average duration of life; a larger proportion of persons now reach the age at which cancer is frequent.

_The prognosis_ largely depends on the variety of cancer and on its situation. Certain varieties--such as the atrophic cancer of the breast which occurs in old people, and some forms of cancer in the rectum--are so indolent in their progress that they can scarcely be said to shorten life; while others--such as the softer varieties of mammary cancer occurring in young women--are among the most malignant of tumours. The mode in which cancer causes death depends to a large extent upon its situation. In the gullet, for example, it usually causes death by starvation; in the larynx or thyreoid, by suffocation; in the intestine, by obstruction of the bowels; in the uterus, prostate, and bladder, by haemorrhage or by implication of the ureters and kidneys. Independently of their situation, however, cancers frequently cause death by giving rise to a progressive impairment of health known as the _cancerous cachexia_, a condition which is due to the continued absorption of poisonous products from the tumour. The patient loses appetite, becomes emaciated, pale, and feverish, and gradually loses strength until he dies. In many cases, especially those in which ulceration has occurred, the addition of pyogenic infection may also be concerned in the failure of health.

_Treatment._--Removal by surgical means affords the best prospect of cure. If carcinomatous disease is to be rooted out, its mode of spread by means of the lymph vessels must be borne in mind, and as this occurs at an early stage, and is not evident on examination, a wide area must be included in the operation. The organ from which the original growth springs should, if practicable, be altogether removed, because its lymph vessels generally communicate freely with each other, and secondary deposits have probably already taken place in various parts of it. In addition, the nearest chain of lymph glands must also be removed, even though they may not be noticeably enlarged, and in some cases--in cancer of the breast, for example--the intervening lymph vessels should be removed at the same time.

The treatment of cancer by other than operative methods has received a great deal of attention within recent years, and many agents have been put to the test, _e.g._ colloidal suspensions of selenium, but without any positive results. Most benefit has resulted from the use of radium and of the X-rays, and one or other should be employed as a routine measure after every operation for cancer.

It has been demonstrated that cancer cells are more sensitive to radium and to the Rontgen rays than the normal cells of the body, and are more easily killed. The effect varies a good deal with the nature and seat of the tumour. In rodent cancers of the skin, for example, both radium and X-ray treatment are very successful, and are to be preferred to operation because they yield a better cosmetic result. While small epitheliomas of the skin may be cured by means of the rays, they are not so amenable as rodent cancers.

Cancers of mucous membranes are less amenable to ray treatment because they are less circumscribed and are difficult of access. In cancers under the skin, the Rontgen rays are less efficient; if radium is employed, the tube containing it should be inserted into the substance of the tumour after the method described in connection with sarcoma--and another tube should be placed on the overlying skin.

In the employment of X-rays and of radium in the treatment of cancer, experience is required, not only to obtain the maximum effect of the rays, but to avoid damage to the adjacent and overlying tissues.

Ray treatment is not to be looked upon as a rival but as a powerful supplement to the operative treatment of cancer.

VARIETIES OF CANCER

The varieties of cancer are distinguished according to the character and arrangement of the epithelial cells.

The _squamous epithelial cancer_ or _epithelioma_ originates from a surface covered by squamous epithelium, such as the skin, or the mucous membrane of the mouth, gullet, or larynx. The cancer cells retain the characters of squamous epithelium, and, being confined within the lymph spaces of the sub-epithelial connective tissue, become compressed and undergo a horny change. This results in the formation of concentrically laminated masses known as cell nests.

The clinical features are those of a slowly growing indurated tumour, which nearly always ulcerates; there is a characteristic induration of the edges and floor of the ulcer, and its surface is often covered with warty or cauliflower-like outgrowths (Fig. 58). The infection of the lymph glands is early and constant, and constitutes the most dangerous feature of the disease; the secondary growths in the glands exhibit the characteristic induration, and may themselves break down and lead to the formation of ulcers.

[Illustration: FIG. 58.--Epithelioma of Lip.]

Epithelioma frequently originates in long-standing ulcers or sinuses, and in scars, and probably results from the displacement and sequestration of epithelial cells during the process of cicatrisation.

The _columnar epithelial cancer_ or _columnar epithelioma_ originates in mucous membranes covered with columnar epithelium, and is chiefly met with in the stomach and intestine. As it resembles an adenoma in structure it is sometimes described as a _malignant adenoma_. Its malignancy is shown by the proliferating epithelium invading the other coats of the stomach or intestine, and by the development of secondary growths.

_Glandular carcinoma_ originates in organs such as the breast, and in the glands of mucous membranes and skin. The epithelial cells are not arranged on any definite plan, but are closely packed in irregularly shaped alveoli. If the alveoli are large and the intervening stroma is scanty and delicate, the tumour is soft and brain-like, and is described as a _medullary_ or _encephaloid cancer_. If the alveoli are small and the intervening stroma is abundant and composed of dense fibrous tissue, the tumour is hard, and is known as a _scirrhous cancer_--a form which is most frequently met with in the breast. If the cells undergo degeneration and absorption and the stroma contracts, the tumour becomes still harder, and tends to shrink and to draw in the surrounding parts, leading, in the breast, to retraction of the nipple and overlying skin, and in the stomach and colon to narrowing of the lumen. When the cells of the tumour undergo colloid degeneration, a _colloid cancer_ results; if the degeneration is complete, as may occur in the breast, the malignancy is thereby greatly diminished; if only partial, as is more common in rectal cancer, the malignancy is not appreciably affected. Melanin pigment is formed in relation to the cells and stroma of certain epithelial tumours, giving rise to _melanotic cancer_, one of the most malignant of all new growths. Cyst-like spaces may form in the tumour by the accumulation of the secretion of the epithelial cells, or as a result of their degeneration--_cystic carcinoma_. This is met with chiefly in the breast and ovary, and the tumour resembles the cystic adenoma, but it tends to infect its surroundings and gives rise to secondary growths.

_Rodent cancer_ originates in the glands of the skin, and presents a special tendency to break down and ulcerate on the surface (Figs. 102 and 103). It almost never infects the lymph glands.

DERMOIDS

A dermoid is a tumour containing skin or mucous membrane, occurring in a situation where these tissues are not met under normal conditions.

The _skin dermoid_, or _derma-cyst_ as it has been called by Askanazy, arises from a portion of epiblast, which has become sequestrated during the process of coalescence of two cutaneous surfaces in development. This form is therefore most frequently met with on the face and neck in the situations which correspond to the various clefts and fissures of the embryo. It occurs also on the trunk in situations where the lateral halves of the body coalesce during development. Such a dermoid usually takes the form of a globular cyst, the wall of which consists of skin, and the contents of turbid fluid containing desquamated epithelium, fat droplets, cholestrol crystals, and detached hairs. Delicate hairs may also be found projecting from the epithelial lining of the cyst.

Faulty coalescence of the cutaneous covering of the back occurs most frequently over the lower sacral vertebrae, giving rise to small congenital recesses, known as post-anal dimples and coccygeal sinuses. These recesses are lined with skin, which is furnished with hairs, sebaceous and sweat glands. If the external orifice becomes occluded, there results a dermoid cyst.

_Tubulo-dermoids_ arise from embryonic ducts and passages that are normally obliterated at birth, for example, _lingual dermoids_ develop in relation to the thyreo-glossal duct; _rectal and post-rectal_ dermoids to the post-anal gut; and _branchial dermoids_ in relation to the branchial clefts. Tubulo-dermoids present the same structure as skin dermoids, save that mucous membrane takes the place of skin in the wall of the cyst, and the contents consist of the pent-up secretion of mucous glands.

_Clinical Features._--Although dermoids are of congenital origin, they are rarely evident at birth, and may not give rise to visible tumours until puberty, when the skin and its appendages become more active, or not till adult life. Superficial dermoids, such as those met with at the outer angle of the orbit, form rounded, definitely limited tumours over which the skin is freely movable. They are usually adherent to the deeper parts, and when situated over the skull may be lodged in a depression or actual gap in the bone. Sometimes the cyst becomes infected and suppurates, and finally ruptures on the surface. This may lead to a natural cure, or a persistent sinus may form. Dermoids more deeply placed, such as those within the thorax, or those situated between the rectum and sacrum, give rise to difficulty in diagnosis, even with the help of the X-rays, and their nature is seldom recognised until the escape of the contents--particularly hairs--supplies the clue. The literature of dermoid cysts is full of accounts of puzzling tumours met with in all sorts of situations.

The treatment is to remove the cyst. When it is impossible to remove the whole of the lining membrane by dissection, the portion that is left should be destroyed with the cautery.

_Ovarian Dermoids._--Dermoids are not uncommon in the ovary (Fig. 59). They usually take the form of unilocular or multilocular cysts, the wall of which contains skin, mucous membrane, hair follicles, sebaceous, sweat, and mucous glands, nails, teeth, nipples, and mammary glands. The cavity of the cyst usually contains a pultaceous mixture of shed epithelium, fluid fat, and hair. If the cyst ruptures, the epithelial elements are diffused over the peritoneum, and may give rise to secondary dermoids.

[Illustration: FIG. 59.--Dermoid Cyst of Ovary showing Teeth in its interior.]

The ovarian dermoid appears clinically as an abdominal or pelvic tumour provided with a pedicle; if the pedicle becomes twisted, the tumour undergoes strangulation, an event which is attended with urgent symptoms, not unlike those of strangulated hernia.

The treatment consists in removing the tumour by laparotomy.

1. Teratoma.#--A teratoma is believed to result from partial dichotomy or

cleavage of the trunk axis of the embryo, and is found exclusively in connection with the skull and vertebral column. It may take the form of a monstrosity such as conjoined twins or a parasitic foetus, but more commonly it is met with as an irregularly shaped tumour, usually growing from the sacrum. On dissection, such a tumour is found to contain a curious mixture of tissues--bones, skin, and portions of viscera, such as the intestine or liver. The question of the removal of the tumour requires to be considered in relation to the conditions present in each individual case.

CYSTS[3]

[3] Cysts which form in relation to new-growths have been considered with tumours.

Cysts are rounded sacs, the wall being composed of fibrous tissue lined by epithelium or endothelium; the contents are fluid or semi-solid, and vary in character according to the tissue in which the cyst has originated.

_Retention and Exudation Cysts._--_Retention cysts_ develop when the duct of a secreting gland is partly obstructed; the secretion accumulates, and the gland and its duct become distended into a cyst. They are met with in the mamma and in the salivary glands. Sebaceous cysts or wens are described with diseases of the skin. _Exudation cysts_ arise from the distension of cavities which are not provided with excretory ducts, such as those in the thyreoid.

_Implantation cysts_ are caused by the accidental transference of portions of the epidermis into the underlying connective tissue, as may occur in wounds by needles, awls, forks, or thorns. The implanted epidermis proliferates and forms a small cyst. They are met with chiefly on the palmar aspect of the fingers, and vary in size from a split pea to a cherry. The treatment consists in removing them by dissection.

_Parasitic cysts_ are produced by the growth within the tissues of cyst-forming parasites, the best known being the taenia echinococcus, which gives rise to the _hydatid cyst_. The liver is by far the most common site of hydatid cysts in the human subject.

With regard to the further life-history of hydatids, the living elements of the cyst may die and degenerate, or the cyst may increase in size until it ruptures. As a result of pyogenic infection the cyst may be converted into an abscess.

The _clinical features_ of hydatids vary so much with their situation and size, that they are best discussed with the individual organs. In general it may be said that there is a slow formation of a globular, elastic, fluctuating, painless swelling. Fluctuation is detected when the cyst approaches the surface, and it is then also that percussion may elicit the "hydatid thrill" or fremitus. This thrill is not often obtainable, and in any case is not pathognomonic of hydatids, as it may be elicited in ascites and in other abdominal cysts. Pressure of the cyst upon adjacent structures, and the occurrence of suppuration, are attended with characteristic clinical features.

The _diagnosis_ of hydatids will be considered with the individual organs. The disease is more common in certain parts of Australia and in Shetland and Iceland than in countries where the association of dogs in the domestic life of the inhabitants is less intimate. Pfeiler, who has worked at the _serum diagnosis of hydatid disease_, regards the complement deviation method as the most reliable; he believes that a positive reaction may almost be regarded as absolutely diagnostic of an echinococcal lesion.

The _treatment_ is to excise the cyst completely, or to inject into it a 1 per cent. solution of formalin. In operating upon hydatids the utmost care must be taken to avoid leakage of the contents of the cyst, as these may readily disseminate the infection.

A _blood cyst_ or haematoma results from the encapsulation of extravasated blood in the tissues, from haemorrhage taking place into a preformed cyst, or from the saccular pouching of a varicose vein.

A _lymph cyst_ usually results from a contusion in which the skin is forcibly displaced from the subjacent tissues, and lymph vessels are thereby torn across. The cyst is usually situated between the skin and fascia, and contains clear or blood-stained serum. At first it is lax and fluctuates readily, later it becomes larger and more tense. The treatment consists in drawing off the contents through a hollow needle and applying firm pressure. Apart from injury, lymph cysts are met with as the result of the distension of lymph spaces and vessels (_lymphangiectasis_); and in lymphangiomas, of which the best-known example is the cystic hygroma or hydrocele of the neck.

GANGLION

This term is applied to a cyst filled with a clear colourless jelly or colloid material, met with in the vicinity of a joint or tendon sheath.

The commonest variety--the _carpal ganglion_--popularly known as a sprained sinew--is met with as a smooth, rounded, or oval swelling on the dorsal aspect of the carpus, usually towards its radial side (Fig. 60). It is situated over one of the intercarpal or other joints in this region, and may be connected with one or other of the extensor tendons. The skin and fascia are movable over the cyst. The cyst varies in size from a pea to a pigeon's egg, and usually attains its maximum size within a few months and then remains stationary. It becomes tense and prominent when the hand is flexed towards the palm. Its appearance is usually ascribed to some strain of the wrist--for example, in girls learning gymnastics. It may cause no symptoms or it may interfere with the use of the hand, especially in grasping movements and when the hand is dorsiflexed. In girls it may give rise to pain which shoots up the arm. Ganglia are also met with on the dorsum of the metacarpus and on the palmar aspect of the wrist.

[Illustration: FIG. 60.--Carpal Ganglion in a woman aet. 25.]

The _tarsal ganglion_ is situated on the dorsum of the foot over one or other of the intertarsal joints. It is usually smaller, flatter, and more tense than that met with over the wrist, so that it is sometimes mistaken for a bony tumour. It rarely causes symptoms, unless so situated as to be pressed upon by the boot.

_Ganglia in the region of the knee_ are usually situated over the interval between the femur and tibia, most often on the lateral aspect of the joint in front of the tendon of the biceps (Fig. 61). The swelling, which may attain the size of half a walnut, is tense and hard when the knee is extended, and becomes softer and more prominent when it is flexed. They are met with in young adults who follow laborious occupations or who indulge in athletics, and they cause stiffness, discomfort, and impairment of the use of the limb. A ganglion is sometimes met with on the median aspect of the head of the metatarsal bone of the great toe and may be the cause of considerable suffering; it is indistinguishable from the thickened and enlarged bursa so commonly present in this situation in the condition known as bunion.

[Illustration: FIG. 61.--Ganglion on lateral aspect of Knee in a young woman.]

Ganglionic cysts are met with in other situations than those mentioned, but they are so rare as not to require separate description.

Ganglia are to be diagnosed by their situation and physical characters; enlarged bursae, synovial cysts, and new-growths are the swellings most likely to be mistaken for them. The diagnosis is sometimes only cleared up by withdrawing the clear, jelly-like contents through a hollow needle.

_Pathological Anatomy._--The wall of the cyst is composed of fibrous tissue closely adherent to or fused with the surrounding tissues, so that it cannot be shelled out. There is no endothelial lining, and the fibrous tissue of the wall is in immediate contact with the colloid material in the interior, which appears to be derived by a process of degeneration from the surrounding connective tissue. In the region of the knee the ganglion is usually multilocular, and consists of a meshwork of fibrous tissue, the meshes of which are occupied by colloid material.

It is often stated that a ganglion originates from a hernial protrusion of the synovial membrane of a joint or tendon sheath. We have not been able to demonstrate any communication between the cavity of the cyst and that of an adjacent tendon sheath or joint. It is possible, however, that the cyst may originate from a minute portion of synovial membrane being protruded and strangulated so that it becomes disconnected from that to which it originally belonged; it may then degenerate and give rise to colloid material, which accumulates and forms a cyst. Ledderhose and others regard ganglia as entirely new formations in the peri-articular tissues, resulting from colloid degeneration of the fibrous tissue of the capsular ligament, occurring at first in numerous small areas which later coalesce. Ganglia are probably, therefore, of the nature of degeneration cysts arising in the capsule of joints, in tendons, and in their sheaths.

_Treatment._--A ganglion can usually be got rid of by a modification of the old-fashioned seton. The skin and cyst wall are transfixed by a stout needle carrying a double thread of silkworm gut; some of the colourless jelly escapes from the punctures; the ends of the thread are tied and cut short, and a dressing is applied. A week later the threads are removed and the minute punctures are sealed with collodion. The action of the threads is to convert the cyst wall into granulation tissue, which undergoes the usual conversion into scar tissue. If the cyst re-forms, it should be removed by open dissection under local anaesthesia. Puncture with a tenotomy knife and scraping the interior, and the injection of irritants, are alternative, but less satisfactory, methods of treatment.

_Ganglia_ in the substance of _tendons_ are rare. The diagnosis rests on the observation that the small tumour is cystic, and that it follows the movements of the tendon. The cyst is at first multiple, but the partitions disappear, and the spaces are thrown into one. The tendon is so weakened that it readily ruptures. The best treatment is to resect the affected segment of tendon.

The so-called "compound palmar ganglion" is a tuberculous disease of the tendon sheaths, and is described with diseases of tendon sheaths.