Vitamin A acid in Darier's disease.

The etiology in Dariers disease (keratosis follicularis) is unknown, but it seems to be that the skin changes are related to a variation of nutritional vitamin A deficiency caused by processes within the organism. The skin condition, in which the main histological change shows follicular dyskeratosis, has a certain similarity to hypovitaminosis A. Several follicular keratoses are influenced by vitamin A or vitamin A acid therapy. The use of vitamin A is limited by its toxicity, but vitamin A acid being less toxic could be an important therapeutic advance in follicular keratoses. In Darier's disease vitamin A acid topically or systemically applied leads to distinct improvement of the skin lesions. Clinically and histologically, some of the treatment effects are similar to effects obtained when using vitamin A. Systemic vitamin A acid (retinoic acid) administration results in elevation of serum levels vitamin A (retinol) and provitamin A (carotene) and after high dosage clinical symptoms develop nearly identical with hypervitaminosis A. Several possibilities regarding the mode of action of vitamin A acid are mentioned.