Synovial chondroma of the ankle in a young child after recent trauma: CT and MR features

We report a case of synovial chondroma of the left ankle in an 11-year-old boy presenting with soft tissue swelling after recent trauma. The noncalcif ied or nonossified intraarticular chondroma arising from metaplastic synovi um has characteristic imaging appearance on computed tomography (CT) and ma gnetic resonance imaging (MRI). A lobulated mass of fluid-like density and signal intensity along with internal septa are characteristic features on C T and MRI. The knowledge of CT and MRI features of noncalcified or nonossif ied synovial chondroma is important to distinguish from the simple or compl icated effusion, hemarthrosis, or other synovial process. (C) 2001 Elsevier Science Inc. All rights reserved.