Secondary Extra-Articular Synovial Osteochondromatosis with Involvement of the Leg, Ankle and Foot. An Exceptional Case

Extraarticular synovial osteochondromatosis is a very rare benign disease whose aetiology may be primary or secondary to pre-existing pathology or after trauma. The diagnosis can be made with plain radiography and CT, and MRI is necessary to evaluate the non-mineralized soft tissue component and assess extension. It must be confirmed with a pathological study by biopsy or resection. There is up to a 5% chance of malignant transformation. The treatment of choice for the extensive extra-articular form is surgery by open resection. The case presented illustrates an atypical form of secondary extraarticular OCS with multiple involvement of the leg, ankle and foot. (C) 2020 Elsevier Espana, S.L.U. and Sociedad Espanola de Reumatologia y Colegio Mexicano de Reumatologia. All rights reserved.