Allergic contact dermatitis to All-trans-retinoic acid; epicutaneous and leukocyte migration inhibition testing.

Two male prison volunteers had severe cutaneous reactions to the initial patch testing of All-trans-retinoic acid containing products being evaluated for irritancy. Muliple patch testing procedures performed throughout one year, along with leukocyte migration inhibition studies, speak strongly for delayed hypersensitivity reactions in these subjects. The failure to document a previous exposure in subjects living in a controlled environment suggests that these responses were cross-reactions to a prior sensitizer, perhaps unique to this environment.