Itching, variable as to degree, is usually present.
#What is the course of favus of the scalp?#
[Illustration: Fig. 66. Achorion Schönleinii X 450. (_After Duhring._) Showing simple mycelium, in various stages of development, and free spores.]
#What are the symptoms of favus when seated upon the general surface?#
The symptoms are essentially similar to those upon the scalp, modified somewhat by the anatomical differences of the parts.
The _nails_, when affected, become yellowish, more or less thickened, brittle and opaque (_tinea favosa unguium_, _onychomycosis favosa_).
Solely to the invasion of the cutaneous structures, especially the epidermal portion, by the vegetable parasite, the _achorion Schönleinii_. It is contagious. It is a somewhat rare disease in the native-born, being chiefly observed among the foreign poor. The nails are rarely affected primarily.
It is also met with in the lower animals, from which it is doubtless not infrequently communicated to man.
#What are the diagnostic features of favus?#
The yellow, and often cup-shaped, crusts, brittleness and loss of hair, atrophy, and the history.
[Illustration: Fig. 67. Epilating Forceps.]
#How would you distinguish favus from eczema and ringworm?#
From eczema by the condition of the affected hair, the atrophic and scar-like areas, the odor, and the history. From ringworm by the crusting and the atrophy. In this latter disease there is usually but slight scaliness, and rarely any scarring.
Finally, if necessary, a microscopic examination of the crusts may be made.
#State the method of examination for fungus.#
A portion of the crust is moistened with liquor potassæ and examined with a power of three to five hundred diameters. The fungus, (achorion Schönleinii), consisting of mycelium and spores, is luxuriant and is readily detected.
Upon the scalp, favus is extremely chronic and rebellious to treatment, and a cure in six to twelve months may be considered satisfactory; in neglected cases permanent baldness, atrophy, and scarring sooner or later result. Although favus of the scalp persists into adult life, it becomes less active and, finally, as a rule, gradually disappears, leaving behind scarred or atrophic bald areas.