1911 Encyclopædia Britannica/Tumour

From Wikisource
Jump to navigation Jump to search

TUMOUR (Lat. tumor, a swelling), a term applied, from the earliest period of medical literature, to any swelling of which the nature and origin were unknown. Thus used in its most literal sense, the word is of purely clinical derivation and has no pathological significance of any kind. Consequently a very heterogeneous collection of swellings have been described as tumours, including such diverse conditions as an abscess, a tubercular gland, the enlarged spleen of malaria or a cancer. With the progress of bacteriology and the improved technique of histology it has been found possible, however, to separate these various “ swellings" into certain groups: (1) Inflammatory or Infective Tumours; (2) Tumours due to Hypertrophy; (3) Cysts; (4) Spontaneous Tumours, or Tumours proper. The tendency of modern convention is to restrict the use of the term “ tumour ” to the last group, but for the sake of completeness it is necessary to touch briefly on the distinguishing features of the first three groups.

1. Inflammatory or Infective Tumours.—These have certain characteristics which separate them sharply from other classes of tumour. In the first place all of them are due to the irritative action of some micro-organism (see Pathology). Inflammation due to microbial action always follows a typical course. First, a number of wandering cells derived from the blood, the lymph or the connective tissues make their way to the site of irritation, and thus produce the red, painful swelling with which every one is familiar. A struggle now ensues between these cells and the invading bacteria; if the victory rests with the former, the inflammation gradually subsides, and the swelling disappears in course of time. But if the bacteria ain the upper hand a number of the cells are killed, undergo liquefaction and are converted into pus, so that an abscess results. Thus an innammatory swelling may be solid or fluid according to the severity of the irritant. The common inflammatory bacteria—staphylococcus and streptococcus—cause suppuration in the majority of cases, but there are a few organisms such as streptothrix, spirochaete pallida, and in many instances the tubercle bacillus, which set up an inflammation of an extremely chronic type, rarely progressing to the formation of us, but leading rather to the development of a hard, solid mass of very slow growth, that may persist for months or even years.

To the naked eye these solid inflammatory swellings may closely simulate the spontaneous tumours with which they have been often confused, but a microscopical examination will correct the mistake in nearly every case. For the minute structure of the infective tumours, whatever their situation, is almost identical; they consist merely of an irregular collection of inflammatory cells; and this of itself is sufficient to mark them oil quite distinctly from the group of tumours proper, which, as will presently be seen, vary widely in structure according to the tissue from which they spring, and show a resemblance to the parent type at once characteristic and peculiar. To this statement there is one exception, for a form of malignant tumour, known as a sarcoma, may bear a very deceptive likeness to an inflammatory swelling.

2. Hypertrophic Tumours.—A tissue or organ is said to be hypertrophied when it is increased in size but remains normal in structure. The most familiar example is the hypertrophy of the skeletal muscles that follows increased use, or the hypertrophy of the heart muscle which helps to compensate the faulty action of the valves. But neither of these constitutes a hypertrophic tumour. For an instance of this we must turn to the enlargement of the spleen that occurs in malaria and certain forms of anaemia, of the thyroid gland in goitre, and of the lymphatic glands in Hodgkin's disease. In each of these conditions there is merely an increase of apparently normal tissue, and from a microscopical examination of the hypertrophied organ it would be impossible to say that it was other than healthy. The enlargement of the spleen and of the thyroid in these cases are overshadowed by certain changes in the blood and in the nervous stem which constitute a distinct disease; but in Hodgkin's disease there are no specific symptoms apart from the swelling of the glands, and it has been suggested that this may be due either to the action of some micro-organism which has hitherto escaped detection, or to a widely diffused growth of a sarcomatous type. If the former supposition be correct these glandular swellings must be classed with the infective tumours; in the latter they should be regarded as spontaneous tumours. There is, at present, no agreement on this point, and they have, therefore, been described here as hypertrophic tumours.

3. Cysts.—A cyst may be defined as a collection of fluid surrounded by a wall or capsule. The nature of the fluid varies according to the site and origin of the cyst; the cyst-wall is usually composed of a tough layer of fibrous tissue. Cystsarisebythe dilatation of a pre-existing space with fluid; and when, as often happens, the cystwall is tensely stretched by the pressure of the fluid within, they may easily 'be mistaken for solid tumours.

The number and variety of cysts are very great, and they are only mentioned here on account of the errors in diagnosis for which the are often responsible. For further details the reader should consug the special textbooks.

4. Spontaneous Tumours, or Tumour; Proper (synonyms: Neoplasm, New Growth).-~The following definition of a spontaneous tumour suggested by Ziegler is perhaps the most satisfactory: "A neoplasm or tumour is a new formation of tissue, which is atypical in structure, serves no useful purpose to the whole economy, and the growth of which has no typical termination. " in this definition the words “ new formation of tissue” exclude the cystic swellings; the attribute “ atypical in structure " excludes hypertrophies; and the final clause “ the growth of which has no typical termination" excludes all swellings of an inflammatory nature which progress, however slowly, towards either suppuration or resolution and recovery.

These tumours arise by the exaggerated and abnormal proliferation of a single cell, or a group of cells. They increase in size solely by the multiplication of their own cells, and the only contribution which the surrounding tissues make to the progress is the formation of a “ stroma, " or supporting framework of fibrous tissue; and even that is wanting in many cases. lnasmuchas the newly-formed cells of the tumour take on the likeness of the parent from which they are sprung, it follows that the minute structure of such a tumour, whatever its situation, will be a more or less exact copy of that of the tissue whence it ori inated. A tumour growing from the skin will therefore imitate tire cell-structure of the normal skin; the resemblance of a breast tumour to the healthy breast is often so close as to make it a hard task to distinguish the one from the other; whilst the similarity of bony and cartilaginous tumours to true bone and cartilage is evident to all. r-This

imitation of the parent type by the spontaneous tumours is one of their most remarkable characteristics, and provides a reliable criterion by which they may be separated from the inflammatory new growths, which are all built u on the same general plan. Consequently it is almost always possible to determine the origin of a tumour from an examination of its histological appearances; and conversely we know that an epithelial tumour will never spring from a connective tissue nor a connective tissue tumour from an epithelium.

Another outstanding feature of the neoplastic tumours is that they lead an entirely independent existence subject to none of the restraints to which the normal cell must needs submit. These normal cells are, indeed, possessed of certain limited powers of multiplication, by which they are enabled to replace the slight loss of tissue which the wear and tear of life perpetually entails; or, again, the can on occasion make good a greater loss of substance, as in the liiealing of an ulcer, or the regeneration of a skin wound. But these powers are confined within certain well-marked bounds, which may not be transgressed. Contrast with this the tumour cell, emancipated from all control and owning to no restraint. It is true that the simple tumours often remain stationary after attaining a certain size, but the general tendency of ali tumours is towards persistent and unlimited growth, and the cancer cell continues its career unchecked by everything save death.

The spontaneous tumours are seen in every tissue and organ of the body, though in some they are relatively infrequent. Nor are they confined to man, for they have been found throughout the vertebrate kingdom. It is often stated that a higher state of civilization has inflicted on European races a greater susceptibility to tumour formation. As to this, reliable evidence is hard to obtain, but such a statement would seem to be only partially true, and the apparent immunity of certain native races is to some extent due to lack of sufficient observations.

It is usual to separate these tumours into two groups: the Nonmalignant, Innocent or Benign, and the Malignant or Cancerous. Of these two groups the latter are the more familiar and have attracted much more attention and study than the former, on account of the danger to life which they involve, but in point of numbers they are greatly outweighed by the first group. Two or more nonmalignant tumours, of the same or different varieties, are often found in the same individual; but with the cancers this is a rare occurrence, and such growths are usually single. The non-malignant tumours are usually rounded in shape. In size they vary enormously; a fibroid tumour may be as small as a pea; a fatty tumour may weigh forty pounds. Often they cease growing after attaining a certain size, but there are very many exceptions to this, and it is seldom possible to predict the subsequent course of one of these growths. They possess, however, four constant characteristics by which they may be distinguished from the malignant variety.

I. A non-malignant tumour, whatever its size, remains localized to the part from which it originates. It is not an “ infiltrating ” growth, that is to say it does not eat its way into the surrounding tissues, but rather pushes them aside, and so may be called “ expansive. " Moreover, it is separated from them by a thin but usually well-marked layer of fibrous tissue known as the “ capsule " of the tumour, which seems to be formed as the result of a slight inflammation that the presence of the tumour always causes among the healthy tissues surrounding it, and may be regarded as a protest on their part against the invasion of the tumour. 2. Non-malignant tumours are not of themselves dangerous to life. They may, however, cause a great deal of pain and even death, when situated in some sensitive or delicate organ.~ For instance, a small tumour may cause intense pain by pressing on 1 nerve, or dropsical swelling of a limb by obstructing a vein, or death from suffocation by blocking the larynx. Nevertheless it remains true that any evil effects are due not to the nature of the tumour, but to its situation, whereas a cancer causes death whatever its position.

3. These tumours never reproducethernselves in distant pa-rts of the body. More than one may be present in the same individual, but each arises independently, and the widespread dissemination so typical of a cancerous growth is never seen.

4. An innocent growth never recurs after operation. The boundaries of the growth are so well defined that complete removal is usually easy, and the operation is a simple and satisfactory proceeding.-Malignant

Tumours, or Cancers.-There are two varieties of malignant tumour: the Sareomata, arising from the' connective tissues; the Carcinomata, arising from epithelial tissues. » It is customary to describe them both as cancers. The main features of these tumours are as follows:-

I. The Injiltrating Nature of a Malignant Tumour.—A cancer follows a course very different from that of an innocent tumour. Its growth has no appointed termination, but continues-with unabated vigour until death;. moreover, it is more rapid than that of the innocent tumours, and so does not permit of the formation of a capsule by the neighbouring tissues. In consequence such-»a tumour shows no well-defined boundary, but from its margin fine tendrils of cancer cells make their way in all directions into the surrounding parts, which gradually become more and more involved in 'the process. Thus a cancer of the breast will attack both the skin covering it and the underlying muscle and bone; a cancer of the intestine will eat its way into the liver, spleen and kidney, until these organs becomeito a great extent replaced by cancer cells, and can no longer perform their proper functions. .

2. Formation of Secondary Growths, or Metastases.—In addition to this spread of growth by direct extension, another characteristic of malignant tumours is a tendency to dissemination, that is, to reproduce themselves in various parts of the body far removed from the original site; so that it is not unusual to find after death that a cancer of the breast has?given rise to secondary, or metastatic, deposits in the lymphatic glands, the lungs, the ribs and other bones, the brain and the abdominal organs. These secondary deposits are due to the tumour cells making their way through the walls of the small lymph and blood vessels and becoming detached by the force of the circulation, by which they are carried to some distant part of the body, there to continue their career of uncontrolled growtlh ' r

The sarcoma ta and carcinoma ta differ somewhat as regards the path of dissemination. The former are vascular tumours, well supplied with blood-vessels; consequently dissemination usually occurs by way of the blood-stream rather than by the lymphatic circulation, and the commonest site for the secondary deposits of sarcoma is the lung. The carcinoma ta are less vascular, and the tendency of the growth is to invade the small lymph channels, so that the first signs of metastases are to be looked for in the lymphatic glands; at a later date these deposits may be spread throughout the body, particularly in the liver and other abdominal organs, the lungs and the bones.

The formation of metastases is of the utmost importance from a clinical point of view, as the suceessof an operation depends on the removal of all the secondary deposits as well as of the original growth. For instance, a few months after the first appearance of a cancer of the breast the axillary lymph glands will be found to be hard and enlarged. This means that some of the cells of the primary growth have been carried in the lymph stream to these glands, and have begun to grow there; consequently any operation for the removal of the cancer of the breast must include the removal of these glands. If the breast tumour only be taken away the rowth will continue unchecked in the glands. It is a matter of great difficulty to determine by the naked eye or the touch whether a gland is infected or not. In man cases where there is no evident enlargement the microscope will show the presence of cancer cel1s; and a certain opinion can only be given after a microscopical eX3.l'1'11l'latlOX'l. Y

In operations for cancer of the breast or tongue the modern practice is to regard the lymphatic glands of the axilla or neck respectively as infected in every case, however early it be, and to remove them accordingly. In other parts of the body where the glands are inaccessible, the only solution of the difficulty is to urge the removal of the tumour at the earliest possible moment, before lymphatic infection has had time to occur.

The frequency and rapidity of metastasis- formation varies greatly. As a general rule cancer of the breast is more liable than other forms of growth to be followed by widespread secondary deposits. On the other hand, in cases of cancer of the skin secondary infection is usually confined to the neighbouring lymphatic glands, and seldom occurs in any of the internal organs. 3. Termination of Malignant T umours.-In one or two well authenticated cases a malignant tumour has disappeared of its own accord without any treatment, and a natural cure may be said to have occurred. But these form such an infinitesimal proportion Of the whole that they do not affect the general truth of the statement that .the universal tendency of a malignant tumour is to cause death.

Although the separation of the new growths into two groups is supported by certain fairly definite characteristics, both clinical and histological, yet it seems likely that the difference between them is one of degree rather than of kind. There is every reason to believe that the same perverted impulse may give rise either to an innocent or a cancerous growth, the issue depending in part on the intensity of the impulse, and in part on the resisting powers of the tissues in which the incipient tumour cells lie. Such a hypothesis is supported by the analogy of the microbial infections, where the final outcome of life or death depends no less on the defensive mechanism of the individual than on the virulence of the infecting organism. Again, it is beyond doubt that occasionally a tumour, which for years has been void of the least taint of malignancy, may become converted into an active cancer. Moreover, certain tumours seem to lie on the border line, for example, rodent ulcers and cancers of the parotid gland. These are malignant in that they are undoubtedly infiltrating tumours, they are innocent in that they never form metastatic deposits. Therefore it seems that malignancy or the reverse is not to be regarded as an absolute and constant attribute of any particular tumour or class of tumours, but rather as an expression of the balance struck in the conflict between the opposing forces of the tumour and its host. .

Histology ol/ Tumours.-On examining a microscopical preparation of an epithe ial tumour it is found to be built up of two distinct elements. There are the epithelial cells, which form the essential part of the tumour; there is a network of fibrous connective-tissue cells, which acts as a supporting framework to the epithelial elements, and is known as the stroma of the tumour. This twofold structure is seen in all the epithelial tumours, both non-malignant and malignant, and in the case of the latter it is a general rule that the greater the proportion of epithelial to connective-tissue elements the faster will the tumour grow. On the other hand in the connective tissue tumours (with the exception of the sarcoma ta) this compound structure is absent and there is only one type of cell present; thus a fatty tumour consists merely of fat cells; a bony tumour of bone cells, and so on.

To understand clearly the differences and likenesses that obtain between the malignant and the non-malignant new growths it is necessary to compare the histology of the two groups. Figs. Ia, Ib represent an innocent tumour (adenoma) of the breast. Figs. 211, 2b a cancer (spheroidal-celled carcinoma) of the breast. Fig. 3 an innocent tumour (papilloma) of the skin. Fig. 4 a cancer of the skin.

Fic. la.-Diagram to show the relations of an innocent tumour (adenoma) of the breast.

a, Tumour; b, normal breast tissue; c, underlying muscular tissue.

FIG. Ib.-Microscopical appearances of an adenoma of the breast. (Drawn from an actual specimen.) a, Tumour cells; b, fibrous connective tissue. In the adenoma the individual cells bear the closest resemblance to the glandular cells of the normal breast from which they are derived. In addition they tend to follow the normal very closely in their arrangement, so that at times it is difficult or impossible to decide which is tumour and which is healthy breast substance. Finally the growth is surrounded by a well defined capsule of fibrous tissue.

FIG. za.-Diagram to show the relations of a malignant tumour (spheroidal cell carcinoma) of the breast. Note the in drawing of the nipple by the growth and the infiltration of the underlying muscle.

a, Tumour; b, normal breast tissue; c, muscle.

Fig. 2b.-Microscopical appearances of a carcinoma of the breast. (Drawn from an actual specimen.) a, Tumcur cells; b, stroma.

In the carcinoma, the individual resemblance is present, though less conspicuous, as many of the cells are irregular in size and shape. But the similarity of the arrangement is very hard to make out or even absent. The cells are arranged in disorderly masses; they'are not enclosed by any semblance of a capsule, but tend to transgress their proper boundaries and invade the underlying muscles. Figs. 3 and 4 show analogous changes in an innocent and in a malignant tumour of the skin.

FIG. 3:*'NOU-malignant tumour (papilloma) of the skin. The tumour is formed by an outward proliferation of the cells of the epidermis, but these cells show no tendency to invade the underlying connective tissue or muscle. (Semidiagrammatic) a, Normal skin. d, Muscular tissue. b, Epithelium or epidermis. e, Papilloma. c, Connective tissue.

Speaking generally it may be said that the cells of an adenoma are fully differentiated and typical of the normal, whereas the cells of a carcinoma show less perfect differentiation, are in some degree and resemble rather the actively growing cells found at an early § tage of embryonic life. . But it is in the cells of a sarcoma that the widest departure from type is seen. A sarcoma is a malignant growth arising from connective tissue, but the resemblance to adult connective tissue is almost non-existent and the cells are essentially of an embryonic type. These differences between the innocent and the malignant cell bear out the well-established physiological rule that the less the functional development of a cell or tissue the greater its power of growth. The primitive impulse is growth, which gives place at a later stage to the development of function.

Site of ulcer

FIG. 4.-Malignant tumour (epithelioma, squamous-celled carcinoma) of the skin. The cells of the epidermis have proliferated both outwardly and inwardly and have invaded and replaced the underlying tissues. An ulcer has been formed on the surface by the necrosis of the superficial cells. (Semidiagrammatic.) In theory it is always possible to distinguish with certainty between an innocent tumour and a cancer by means of the microscope. In practice this is, unfortunately, not the case. There are some tumours whose histological appearances seem to be on the borderline between the two conditions, and often these are the very cases in which the clinical features give no direct clue to their nature. In such circumstances it is only 'by taking into consideration every detail, both clinical and pathological, that an opinion can beformulateg, and even then it remains to some extent a matter of guessw'OI

The Causation of Tumours.-An enormous number of suggestions as to the causation of tumours have been put forward from time to time. Many of these were at the outset quite untenable, and reference can only be made here to the more important. First in point of time came Vircho'w's hypothesis that tumours arise as the direct result of irritation or injury. Many examples of such a sequence of events are familiar to everybody. A cancer of the lip or tongue will often follow the irritation of a clay pipe or a jagged tooth; a tumour of the breast is often attributmil to a blow. But, on the other hand, there must be innumerable instances in which such a cause of irritation has not been followed by a tumour; and it is necessary to discount the natural anxiety of mankind to seek a cause for every unexplained occurrence, so that a slight injury which under ordinary circumstances would be forgottenlis branded as the undoubted cause of any tumour that may subsequently make its appearance. As a complete explanation Virchow's hypothesis is insufficient, but it is quite probable that irritation may have an accessory or predisposing influence in tumour formation, and that it may be enough finally to upset the balance of a group of cells, which for some other reason were already hovering on the brink of abnormal growth.,

There is one peculiar .form or irritation that demands special attention, that is exposure to the X rays. It is beyond doubt that exposure to these rays will cause cancerous ulceration of the skin; though what is the constituent of the rays that produces this effect is not known. Fortunately the danger can be obviated by the use of rubber gloves.

C0hnheim's Hypothesis of Embryonic Remnants.—According to Coh nheim more cells are produced in embryonic life than are required for the development of the body, and a remnant is left unappropriated. Dwing to their embryonic nature, these cells possess an exaggerated power of proliferation, and if at a later period- of life this should be roused into activity by some mechanical or other form of stimulus, their rate of growth will outstrip that of the adult cells and a tumour will develop. As with Virchow's so with Cohnheim's hypothesis. It is at best only a partial explanation which may be applicable to a small proportion of tumours; and it could never account for X-ray cancer, or the inoculability of mouse cancer. .

The Parasitic hypothesis is still a matter of keen debate. In some degree cancer with its localized primary growth and widespread secondary deposits resembles certain infective diseases of microbial origin, such as pyaemia, where from a small prima site of infection the bacteria become disseminated throughout thergody. From this analogy it was argued that tumour formation was due to the activity of some parasite. But if the mode of dissemination of a cancer and of aimicro-organism be carefully examined this analogy is found to be false. When a micro-organism lodges in a gland or other art of the body, by its irritative action it stimulates the cells of that gfand to increased activity, and any swelling that occurs is produced by the proliferation of those cells. But when a group of cancer-cells is deposited in a gland the subsequent growth arises entirely from the multiplication of those cancer-cells, and the gland cells take no part whatever in its formation.,

A very large number of organisms both -animal and vegetable have been described as occurring in tumours; and some of these have been cultivated on artificial media outside the body; but to none of them can any direct causal relationship with cancer be attributed. One of the best authenticated, a small coccus, known as .Mierococcus neoforrnans can certainly be cultivated from many tumours malignant and innocent, and it has been suggested that it may be responsible for the slight inflammatory changes that occur in the neighbourhood of most new growths. The final and critical test of the connexion of an organism with some diseased condition is the production of a similar condition in animals by inoculation of that organism, and this experiment has signally failed with all the suggested cancer parasites. Another very cogent argument against the infective hypothesis is the fact that although tumours of identical structure are found throughout the vertebrate kingdom, it has never yet been found possible artificially to transmit these tumours from one species to another. If they were of an infective nature it is almost inconceivable that the gap between two allied species should be such an insuperable bar to transmission.

Quite recently Borrel of the Pasteur Institute has stated that certain animal parasites from the skin are often to be found buried in the cell masses of cancers of the skin and breast, and he thinks that these parasites may be the carriers of some as yet unknown cancer virus, just as the mosquito is the carrier of malaria. Ribbert has suggested that tumour formation may be due to “ alteration of tissue tension.” In his opinion the various cells of the body are normally held in a state of equilibrium by some condition of mutual interdependence . amongst themselves. Should this equilibrium be disturbed some of 'these cells may escape from the controlling influence usually exercised upon them by their neighfilours, and become endowed with greatly enhanced powers of rowt .

g Adami considers that every cell possesses two distinct roper ties, a property of function and a property of growth, and fic regards these as incompatible, that is to say, a cell cannot at the same time be carrying out a specific function and also undergoing active growth. He believes that on occasion some of these cells may abandon their “ habit of work " and assume a “ habit of growth, ” and this will lead to the development of a tumour.

Neither of the two latter explanations brings us very much nearer the solution of the question-they merely place the unknown factor one step farther back; but they serve to emphasize the biological aspect of the problem. At the present time the general weight of evidence seems to favour the idea that tumour formation is due to some intrinsic cause, whereby the normal processes of growth are disturbed, rather than to any extrinsic cause such as microbial infection. Therefore it is from a careful study of the laws of growth, and from research directed along broad biological lines that the best results are to be looked for in the future. Classification of Spontaneous Tumours.-So little is known as to the nature of these tumours that a satisfactory classification on a scientific basis is not yet within reach. The following is merely suggested as convenient:-

I.-Connective-tissue Tnmours.

Innocent. Malignant.

Liporna (fatty tumour).

Fibroma (fibrous tumour). Sarcoma.

Myoma (muscular tumour). Endothelioma.

Osteoma (bony tumour).

Chondroma (cartilaginous tumour).

Odontoma (tumour in connexion with teeth). Myxoma (mucoid tumour).

Neuroma (tumour in connexion with nerves). Glioma (neuroglial tumour).

Endothelioma (endothelial tumour).

Angioma (tumour composed of blood vessels). II.-Epithelial T umonrs.

I nnocent. M alignant.

Papilloma. Carcinoma.

Adenoma. Rodent Ulcer.

I. Connective-tissue Tnmonrsl-Lipoma (fig. 5).-Of the connective-tissue group the fatty tumours are the most common. They often arise from the layer of fat beneath the skin, and a usual site for these subcutaneous lipomata is the back of the trunk, though at times they are found on the limbs and elsewhere. They 1 Figs. 5, 6, 7, 8, 9, 14, 15 and 17 have been redrawn from Bland Sutton's Turnours, by permission; figs. 10, 11, 12 and 13 are from Rose & Carless, Surgery, by permission. V are soft, painless swellings, sometimes of great size; though usually single, as many as a dozen may be present in the same individual . Lipomata are also found in the abdominal cavity, growing from the sub peritoneal layer of fat.

FIG. 5.—Lipoma of the palm. What is known as a dffuse lipoma (fi . 6) consists of a generalized overgrowth of the subcutaneous fat o the neck, and this may be t . so extensive as to obliterate he outline of the Jaw.

FIG. 6.-Difiuse lipoma of neck. Fibroma (fig. 7).-Of tumours containing fibrous tissue, by far the most important are the fibroids of the uterus. A better name

for these tumours would be Fibrornyomata, as they always contain a varying proportion of muscle fibres. They originate in the wall of the uterus, but generally come to project either internally into the cavity of the uterus, or externally into the peritoneal cavity; and often their sole Connexion with the uterine wall is a stalk or pedicle formed from the capsule of the tumour. Fibromyomata of the uterus are most common from 35 to 45 years of age; in girls under 20 they unknown. They are almost may attain a great size and multiple. They are often seem to be equally common

and unmarried in married FIG. 7.—Uterus in sagittal section Women- N0t eV¢1'Y fibfoid is showing interstitial and sub mucous 3 50Ul'C€ Of danger 0' d1SC0m iibroids. fort, for in the majorit of cases they are discovered by chance or not until after death. On the other hand they may give rise to severe symptoms, and that in many different ways. First, the may cause haemorrha e prolonged over years so that the health is entirely ruined. gecondly, they may become inflamed and septic, and lead to severe blood-poisoning. Next, for some unknown reason, a fibroid tends to prevent conception, whilst, should pregnancy occur, labour is greatly impeded. Finally, it seems to be established that a fibroid may occasionally become converted into a sarcoma. Examples of pure fibrous tissue tumours are the small multiple growths of the subcutaneous tissue, known as Painful subcutaneous nodule, and the irregular outgrowth from the gum known as Epulis. A Myoma is composed of unstriped muscle fibres. It is a rare tumour sometimes found in the oesophagus, stomach and bladder, Osteoma (fig. 8).-Bony tumours not infrequently arise from the bones of the head or face. They grow very slowly, and are so hard FIG. 8.-Osteoma of the left frontal sinus (seen from below). that surgical removal may be very difficult. They also occur as irregular out rowths from the bones of the limbs. and are then known as Exostoses gfig. 9). A common site for these is the inner and lower end of the femur, at the point of attachment of the adductor muscle, and Such a tumouf Seems to originate from an ossification of the tendon of this muscle.

FIG. 9.—Exostosis of the femur Pfoduced bY the 0SSl5Catl0U Of the FIG. Io.-Multiple chondromata tendon of the adductor magnus. of the finger5

§ 'hondroma (fig. Io).-Cartilaginous tumours are *often found in children and' young people growing from the bones of the limbs in the neighbourhood of the joints. They are frequently multiple, especially in the hands and feet. These tumours grow slowly and are quite painless. Should removal be necessary, it is usually an easy matter.

Qdontgmaf-Several varieties of this tumour have been described arising in Connexion with the teeth and due to delayed or faulty development. They' may cause great deformity of the jaw.

A Myxoma is composed of loose, gelatinous connective tissue similar to that found in the umbilical cord. Some nasal polypi seem to be of this nature, but true myxomatous tumours are rare. It is, however, not uncomm on for a fibroma or a sarcoma to be converted by degeneration into myxomatous-like tissue.

Neuroma.-A pure neuroma is very uncommon, but a tumour known as a Pseudo-neuroma (fig. II) is often found in the course of a nerve. This is formed by a localized overgrowth of the fibrous tissue of the nerve sheath.

Glioma.—This variety of tumour arises from the neuroglia, the supporting tissue of the brain and spinal cord. Consequently gliomata are only found in these two structures. it

FIG. II.-Pseudo-neuroma: fibrous tumour growing from nerve sheath, and causing the fibres to be stretched over it. cavernous naevus the vascular hypertrophy is on a may produce a definite pulsating tumour. Here, is the usual situation. Sarcoma.-This is the malignant type of the tumour. The general arrangement of a sarcoma

Endotheliomar-Of late years a small class of tumour has been described as originating apparently from the endothelium lining the lesser blood and lymph channels. Many of the recorded examples have been connected with the mouth, the tongue, the palate or the parotid gland. Some of these tumours are quite innocent, others are typically malignant. An Angeioma consists of a meshwork of blood-vessels bound together by a small amount of fat and fibrous tissue. Two varieties are described: (a) The simple naevus, or port-wine stain, scarcely deserves to be called a tumour. It appears as a reddish-blue discolouration of the skin due to over growth and dilatation of the underlying blood-vessels. This condition is most commonly found on the face or scalp, and may be of congenital origin. (b) In the larger scale, and again, the head connective-tissue shows a mass of atypical cells loosely bound together by a small amount of connective tissue. The cells vary greatly in size and shape in di erent tumours, and in accordance with the prevailing type the following varieties of sarcoma have been described: ~ (i.) round-cell sarcoma, (ii.) spindle-cell sarcoma, (iii.) melanotic sarcoma, (iv.) myeloid sarcoma. The first two groups contain the great majority of all sarcoma ta, and may occur in almost any part of the body, but they are especially liable to attack the bones (fig. 12). A sarcoma of bone may be either periosteal when it grows from the periosteum covering the outer surface of the bone, or endosleal when it' lies in the medullary cavity. A peculiar form of sarcoma is found in the parotid and other salivary glands. The cells are usually spindle- shaped, and among t em lie scattered masses of

FIG. 12.-Ossifying periosteal sarcoma of fibula. cartilage and fibrous tissue. These tumours are seldom very malignant, and dissemination is rare (fig. 13). The melanotic sarcoma is of a brown or black colour owing to the presence of granules of pigment (melanin) in and among the tumour cells. A melanotic sarcoma may arise from a pigmented wart or mole, or

FIG. 13.-Malignant tumour of the parotid gland. from the pigmented layers of the retina. The primary growth is usually small, but dissemination occurs with great rapidity throughout the body. The myeloid sarcoma, or myeloma (fig. 14). is composed of very large cells like those of bone-marrow from which it is probably derived. It is only found in the interior of bones, chiefly in those of the arm and leg. The degree of malignancy is low, dissemination never occurs, and recurrence after operation is rare.

FIG. 14.-Lower end of a femur in longitudinal section, showing a myeloma. - II.-Epithelial Tumours. Papilloma.-The familiar example of a papilloma is the simple wart, which is formed by a proliferation of the squamous epithelium of the skin (fig. 3). It seems probable that some warts are of an infective nature, for instances of direct contagion are not uncommon. Occasionally warts are pigmented, and are then liable to be the seat of a melanotic sarcoma. Papillomata are also found in the bladder (fig. 15), as long delicate filaments growing from the bladder wall. These consist of a connective tissue core covered by a thin layer of epithelium.

Azlenoma.-(Figs. IG and lb). The glandular tumours are of very common occurrence in the breast, the ovary and the intestinal cana . The structure of an adenoma of the breast has already been described (vide supra), and the structure of other adenomata is on the same general plan. The main features of an innocent glandular tumour are: (a) the presence of a rounded, painless swellin with a well-defined margin; (b) the swelling is freely movabie in the surrounding tissues, and if it lies close beneath the skin it is not attached thereto; (c) there is no enlargement of the neighbouring lymphatic glands., carcinoma.—The following varieties of carcinoma are described:-i. Squamous-cell carcinoma (fig. 4), arising from those parts of the body covered by squamous epithelium, namely the skin, the mouth, the pharynx, the u per part of the oesophagus and the bladder. ii. Sgheroidal-cell carcinoma (figs. 26 and 2b), arising from spheroi al epithelium, as in the breast, the pylorus, the pancreas, t e kidney and the prostrate. iii. Columnar-cell carcinoma (figs. 16 and 17), arising from columnar epithelium, as in the intestine.

The general histology of these tumours corresponds to that of a spheroidal-cell carcinoma already described (vide supra), the only variation between the three groups being in the shape of the cells. The clinical characteristics of a carcinoma, whatever its situation, are: (a) the presence of a swelling which has no well defined maxlgin, but fades away into the surrounding tissues to which it is fixe; (b) when the tumour lies near the skin (e.g. a carcinoma

FIG. 15.-Villous papilloma of the bladder. of the breast) it becomes fixed to this at an early date; (6) the tumour is painful and tender, the degree of pain varies widely, (Redrawn from Ziegler's Pathological Anatomy, by permission of Macmillan & Co.)

FIG. 16.-Section through advancing margin of columnar; cancer of stomach.

and in the early stages there may be none; (d) the neighbouring lymphatic glands soon become enlarged and tender, showing that they are the seat of metastatic deposits; (e) in squamous carcinoma of the skin, ulceration speedily occurs.

Rodent Ulcer.—This shows itself as a slowly progressing ulceration of the skin, and is especially common on the face near the eye or ear. The condition is one, of purely local malignancy, and dissemination does not occur. It is believed to be a carcinoma of the sebaceous glands of the skin.  (L. C.*)