UV radiation and keratosis follicularis.

We carried out provocation studies on the lesions of keratosis follicularis by the use of UV radiation. Nonerythema-producing doses of UV-B elicited the lesions in uninvolved skin sites in a 34-year-old man with this disease. The elicited lesions were compatible with those of keratosis follicularis both clinically and histopathologically. Similar irradiation with UV-A produced no visible changes in the test area.