Fig. 105
Guinea-worm bleb just cut off. (Bryant.)
Blastomycetic Dermatitis.
—This is a true protozoan infection of the skin, first described by Wernicke in 1892, which has now become quite generally recognized and described. The parasite is a very small, spheroid protozoan, and is found in the skin elements, as well as in the pus and debris discharged from the lesions. It has been successfully cultivated and inoculated. It is classed among the yeast fungi. It produces lesions very much like some of those met with in syphilis, tuberculosis, and mycosis fungoides. Indeed it may be necessary to use the microscope in order to complete the diagnosis, which is best accomplished by teasing a small portion of tissue on the slide in liquor potassæ (Hardaway).
The lesions begin usually as small papules, which may later coalesce and become covered with a fine scab. Around these there develop thickened borders, with fungus-like projections. Between the little elevations pus may form, or an exudate occur in sufficient quantity to dry into a large-sized crust. Here, as in lupus, cicatrization may be going on at interior points while the lesion is encroaching around the margin. The affection is slow, and the ulcer may attain a size of several inches in diameter.
The treatment consists in radical measures, i. e., strong caustics, curetting or complete extirpation with the knife, which may be followed by more or less plastic work, as required.
Coccidioidal Granuloma.
—Under this name is described a rare form of granulomatous lesion of the skin, whose exciting cause is not one of the ordinary bacteria, but a form of mold—one of the varieties of oidium. The clinical manifestations of this lesion resemble those of blastomycetic dermatitis, save that in the latter the primary focus of infection is always found in the skin and remains there localized, whereas coccidioidal granulomas may occur as well in the deeper tissues or viscera as upon the skin; in fact, the skin lesions of the latter may be described as oidiomycosis in distinction from blastomycosis. It produces miliary skin nodules which closely resemble tuberculous lesions, and may even caseate or assume an acute type and break down rapidly. The lesions are progressive, with a tendency to dissemination, both by the lymph and the blood currents. The lymph nodes are usually early affected and often suppurate.