Mucinosis follicularis provoked by light exposure.

The present paper reports a study on a case of follicular mucinosis exacerbated by sunlight exposure. Provocation with standardized light testing was carried out on both normally pigmented skin and on areas of hypopigmentation representing a residual state after earlier skin lesions but without any signs of active mucinosis follicularis. Typical clinical and histologically verified lesions were provoked by the light test procedure, best seen in hypopigmented areas but with similar changes in normally pigmented skin. Characteristic findings developed gradually, assuming an appearance identical with that of the observed spontaneously elicited lesions after 3--4 weeks. Treatment with carotenoids periodically over several years has provided a proper light protective effect, as only minimal lesions have been noted during these periods, compared with extensive changes during similar periods without treatment.