Darier's keratosis follicularis: an ultrastructural study during and after topical treatment with retinoic acid alone or in combination with 5-fluorouracil.

An ointment containing 0.05% retinoic acid (RA) was applied to the anterior surface of the chest in a patient suffering from Darier's keratosis follicularis. A mixture of two ointments containing equal amounts of 5% 5-fluorouracil (5-FU) and 0.05% RA was used on the dorsum of the same patient. Biopsies were taken 30 days and 70 days after treatment started. Retinoic acid gave rise to an initial disorganisation of desmosomes; the "corps ronds" and "grains" disappeared, the lacunae gradually decreased in size, and the epidermis was practically normal when the clinical manifestations of the skin had disappeared. The damage induced with the RA + 5-FU mixture was more serious, but when the skin lesions relapsed they did so later and in a less severe way than the recurrences observed after treatment with RA alone.