ochronosis
UK /ˌəʊ.kɹə(ʊ)ˈnəʊ.sɪs/US /ˌoʊ.kɹəˈnoʊ.sɪs/
noun1
- Abnormal brown pigmentation of tissue (especially cartilage and ligaments), specifically that resulting from the accumulation of a melanin-like pigment derived from homogentisic acid in the metabolic disorder alkaptonuria.