Further experience with toxic vitamin A therapy in pityriasis rubra pilaris.

A patient with short-duration pityriasis rubra pilaris was successfully treated with high-dose, toxic vitamin A (retinol), but the disease subsequently recurred in new areas. Serum levels of vitamin A were highest four hours after treatment and returned to the base level within twelve hours. Fasting blood levels of vitamin A during treatment increased to five times the pretreatment level. Ultrastructural changes in the keratinocytes were notable vacuolation, granularity of the cytoplasm, and a decrease in tonofilament masses, all indications of the cellular effect of the vitamin A. We believe that patients with long-duration pityriasis rubra pilaris should be considered for this treatment.