Alkaptonuria and ochronosis: case report and review.

Alkaptonuria is a rare genetic disorder in which the enzyme homogentisic acid oxidase is deficient, resulting in the accumulation of homogentisic acid in various bodily tissues. This is a multisystem disorder with a characteristic blue-black discoloration of the skin and cartilage, which is termed ochronosis. Herein we report a profound case of ochronosis secondary to alkaptonuria. Furthermore, we review the clinical manifestations of alkaptonuria and discuss the spectrum of ochronosis, both endogenous and exogenous.