Exogenous ochronosis: case report and literature review.

Exogenous ochronosis is a rare, cosmetically disfiguring condition, resulting from the longterm use of topical hydroquinone in treatment of melasma. It manifests as gray-brown or blue-black macules in hydroquinone-exposed regions. The exact incidence of ochronosis is unknown. High rates have been reported in the South African population, and it is rare in the United States. We report the case of a patient who developed exogenous ochronosis while using topical hydroquinone. It is necessary to recognize this disorder at the earliest stage and discontinue hydroquinone immediately, as its treatment is difficult. Sun exposure facilitates the formation of exogenous ochronosis and must be strictly avoided, although it is a practical problem in the tropical climate of Brazil, particularly for those who work outdoors.