Alterations of clinically normal skin in early eruptive guttate psoriasis. A light- and electron-microscopic study.

In clinically normal skin of early eruptive guttate psoriasis, in patients with psoriasis for the first time, the epidermal changes were restricted to small tissue areas showing a slight hyperplasia and a condensed stratum corneum but no parakeratosis. The center (zone 1) of the small tissue areas was characterized by (1) exoserosis with spongiotic dilatation of the intercellular space in the non-cornified epidermis, (2) derangement of keratinocytes with respect to shape, orientation, and number of desmosomes and fibrils, (3) dyskeratotic keratinocytes of two types, A and B, (4) agranulosis restricted to the dyskeratotic deratinocytes of type A, (5) exocytosis of mononuclear cells and Langerhans' cells into the entire non-cornified epidermis, (6) large gaps in the basement membrane between the dermis and epidermis. No polymorphonuclear leukocytes were seen. The periphery (zones 2) of the small tissue areas showed slight changes. The alterations of the upper dermis were slight: besides a very mild general inflammatory reaction with capillary dilatation and perivascular cell infiltrate there was also a focal accumulation of inflammatory cells immediately beneath the epidermis, with cells seemingly infiltrating the stratum basale. It is postulated that the epidermal and dermal changes as shown here represent primary posoriatic changes.