Polychondritis and Arthritis in a Patient with Coexisting Alkaptonuria and Psoriasis Vulgaris.

Alkaptonuria is an organic acid metabolic disorder caused by abnormalities of the tyrosine metabolic pathway. Herein, we report a case of relapsing polychondritis and arthritis in a patient with alkaptonuria and psoriasis vulgaris, respectively. A 53-year-old man, previously diagnosed with alkaptonuria and psoriasis vulgaris, was found to have auricular thickening and tenderness, bilateral bulbar conjunctival injection, and elevated C-reactive protein levels. Ultrasound imaging revealed enthesitis in the bilateral knee joints. A biopsy of the auricular cartilage revealed lymphocytic infiltration. The coexistence of ocular involvement, auricular chondritis, and enthesitis was considered indicative of alkaptonuria complicated by relapsing polychondritis and psoriatic arthritis.