ochronosis
/ˌəʊkrə(ʊ)ˈnəʊsɪs/Medicine
noun
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.
Origin
Mid 19th century. From German Ochronosis from ancient Greek ὠχρός pale yellow + νόσος disease + -osis.