Diagnosis. Microscopical examination is necessary to distinguish this disease from scabies or ringworm.
The prognosis is grave, because large areas of the skin may be invaded in succession.
Treatment. As in acute eczema, the condition is improved by the prolonged administration of small doses of salines and diuretics. Arsenical preparations are also valuable, but should only be employed for two or three weeks together, with intervals of equal duration. The dangerous complications which sometimes result from accumulations of this drug in the system are thus avoided.
SEBACEOUS OR SEBORRHŒIC ECZEMA.
Whilst the two preceding forms of eczema result from vascular disturbance of the skin or dermis that now under consideration seems due to vascular and secretory troubles in the accessory structures of the skin, and more particularly in the sebaceous glands.
Fig. 242.—Sebaceous eczema, first stage. Depilation of the extremities.
Symptoms. The disease develops slowly. At first circular or elliptical patches of skin, distributed regularly over the body, more especially round the natural orifices, become deprived of hair. The surface of these patches is covered either with thick crusts of a peculiar greyish-brown tint which display numerous superficial cracks, or parts normally free from hair exhibit shining epidermic crusts arranged in layers, which are shed on the slightest touch.
This depilation has a strong tendency to spread, and so at first it often resembles ringworm. It results from changes in the hair follicles, with atrophy of the papillæ and complete loss of hair. The changes in the skin, however, are little marked. The skin itself is but slightly thickened and preserves its usual suppleness, while the subcutaneous tissue is not œdematous.
