PRIMARY HISTOLOGIC LESION OF SEBORRHEIC DERMATITIS AND PSORIASIS

[摘要] Biologic analysis of histologic sections of seborrheic dermatitis, psoriasis, and other psoriasiform tissue reaction suggests the rhythmical discharge of leukocytes and serum from the tips of engorged capillaries as a unifying pathognomonic feature. The products of the squirting papilla enter the suprapapillary plate of the epidermis through a temporary break in the basement membrane and cause damage to keratinocytes in a small circumscribed area. Formation of a parakeratotic mound is followed by elimination of a lenticular mass consisting of parakeratotic cells, leukocytes, and fluid through the horny layer. Variable combinations of these events aid in the differential diagnosis of the psoriasiform reactions, which include entities not necessarily related in a nosological sense.