Just as in syphilis, in a very small proportion of cases of leprosy there is a complete absence of constitutional symptoms prior to the appearance of the specific skin eruption.
4. The primary exanthem.— In a considerable proportion of cases, after a longer or shorter period of indifferent health, sometimes preluded by an outburst more severe than usual of fever and other prodromal phenomena, an eruption appears on the skin. This generally coincides with, or is soon followed by, an improvement in the general health.
Although strictly macular, this eruption the primary exanthem of leprosy— varies in different cases as well in respect of the size of the spots as of their number, duration, and other characteristics. They may be no larger than a millet-seed, or they may occupy surfaces many inches in diameter; they may be numerous, or there may be only two or three. The earlier spots are usually purely erythematous, disappearing on pressure, and being darkest in the centre and shading off towards the periphery. But in some cases they may be pigmented from the outset; or they may be mere vitiliginous patches; or all three forms of macula may concur in the same individual— erythematous, pigmented, and vitiliginous. In not a few lepers what in the first instance was an erythematous patch may in time become pigmented, or it may become pale; in the latter case the loss of pigment is usually associated with a certain degree of atrophy of the cutis. Or it may be that the centre of an erythematous patch clears up, the periphery of the patch remaining red and perhaps becoming pigmented; so that the affected spot comes to present the appearance of a red or dark ring, or portion of a ring, enclosing a patch of pale, usually anaæthetic skin. In certain instances the eruption of the various forms of maculæ may be preceded by local paræsthesiæ, such as a sense of burning, tingling, pricking, and so forth.
At first the maculæ may be evanescent and may fade wholly or in part in the course of a few days, weeks, or months; but as the disease progresses, and
