Aortic Valve in Black: A Case of Aortic Valve Ochronosis

Alkaptonuria is a rare inherited tyrosine metabolism disorder, resulting in homogentisic acid deposition in the connective tissues. The condition is commonly referred to as ochronosis and manifests as skin pigmentation, degenerative arthropathy, and black urine. Among the rare complications of this disease is the involvement of the cardiovascular system. We report a case of a 63-year-old woman with alkaptonuric ochronosis who had already undergone three joint replacements. She was referred to our center for aortic valve replacement after accidentally discovering severe aortic valve stenosis in the preoperative assessment prior to her fourth joint replacement. Intraoperative findings included ochronosis of a severely calcified black-pigmented aortic valve and black pigmentation of the aortic intima. Histopathological analysis and elevated homogentisic acid levels in the patient’s urine confirmed the diagnosis of alkaptonuria. However, alkaptonuria was not diagnosed until aortic valve replacement despite the previous symptoms and signs. This report aims to outline the history, etiology, pathogenesis, clinical presentation, and treatment of aortic valve ochronosis in addition to presenting the case.