The clinical manifestations of ochronosis: a review.

Ochronosis is a rare disease caused by an inherited lack of homogentisic acid oxidase. Alkaptonuria is the presence of homogentisic acid in urine. Ochronosis is characterized by the deposition of a dark pigment in tissues rich in collagen. A wide spectrum of clinical manifestations is described. The most important signs are ochronotic arthropathy, ocular and cutaneous pigmentation, genitourinary tract obstruction by ochronotic calculi and cardiovascular ochronosis, especially calcification and stenosis of the aortic valve. The constellation of these clinical signs should suggest the diagnosis which is confirmed by the detection of homogentisic acid in urine. There is no cure for the disease and treatment is based on symptomatic measures.