Ochronosiss presenting as a lytic lesion in the tibial diaphysis

Abstract

Alkaptonuria is a rare metabolic disease with autosomal recessive transfer caused by a congenital deficiency of homogentisic acid oxidase enzyme. The case is here presented of a 62-year old male, who was one of two siblings diagnosed with alkaptonuria and ochronosis and followed up in our clinic. Due to homogentisic acid accumulation, there was multiple joint involvement in the patient, including vertebrae. Total knee arthroplasty was applied to the patient in two separate sessions because of advanced stage bilateral knee osteoarthritis. Widespread lytic appearance in the diaphysis causing isolated tibia involvement was observed, which has not been previously observed in literature. As a result of the examinations made, this condition which was mimicking a tumour, suggested that with ageing the accumulation of homogentisic acid had advanced to the diaphysis.