Early dermato-pathological signs during bath-PUVA therapy.

The combination of trioxsalen bath and long-wave UV-A is used in dermatology to treat selected patients with psoriasis. Such treatment induces side effects whose clinical aspects have already been described. We report the histological aspects of these lesions. The most striking features occur in the epidermis, where we found vacuolar alterations, disorganization of the stratum malpighi, necrotic cells, and Bowenoid changes. Langerhans cells are reduced in number, and melanocytes may become large and atypical. In addition, factor XIIIa-positive dendrocytes of the superficial dermis increase in size, and some of them migrate into the epidermis, which is a rare location for these cells.