Epidermodysplasia verruciformis. Clinical and light- and electron-microscopic observations during etretinate therapy.

Three patients with epidermodysplasia verruciformis (EV) were treated with etretinate for 9-13 months. The patients had lesions characteristic of EV, including flat warts, common genital warts, pityriasis-versicolor-like lesions and malignant changes such as actinic keratosis and Bowenoid cancer in situ. During etretinate treatment, some flattening of the warts was observed in all three patients, and the lesions on the chest and back became less red and scaling. However, none of the lesions disappeared completely, and when the treatment was discontinued, the lesions relapsed. No malignant changes were detected during the period of therapy. Electron microscopy revealed the presence of typical large, clear cells containing viral particles in the upper epidermis. Etretinate therapy induced the same type of fine-structural changes as those seen in keratinization disorders and genodermatoses. The clear cells and virus particles persisted throughout the treatment period. More long-term, controlled studies are necessary to make possible an estimate of the curative and cancer-inhibitory effect of etretinate treatment in patients with EV.