Lichen planus-like photosensitive dermatitis due to pyritinol hydrochloride occurred in a 62-year-old man. Pigmentation intermingled with depigmentation as melanoleukoderma remained after involution of the eruption on the forehead and occipital region. A photosensitization period of five or six weeks' duration was found, and the photopatch test was positive. This case is considered to be due to photoallergy.
Ishibashi A, Hirano K, Nishiyama Y. Photosensitive Dermatitis Due to Pyritinol. Arch Dermatol. 1973;107(3):427-428. doi:10.1001/archderm.1973.01620180077024