Pigmented Villonodular Synovitis of the Ankle

Abstract

A 24-year-old woman presented with painful swelling of the left ankle lasting for several months. She denied any history of prior trauma or surgery. Her level of C-reactive protein was 2.4 mg/L (normal reference <6 mg/L). Plain radiographs showed an area of soft tissue density in the anteromedial aspect of the left ankle joint. Magnetic resonance imaging (MRI) revealed a 3.4×2.3×3.7-cm soft tissue lesion in the anterior aspect of the ankle with compression and displacement of the extensor digitorum longus and the extensor hallucis longus. The lesion exhibited dark T1 and T2 signals (Pictures 1, 2), intermediate to low signals on fat-saturated proton density-weighted images and heterogeneous enhancement following gadolinium administration. Under suspicion of a diagnosis of pigmented villonodular synovitis (PVNS) of the intertarsal joint, the patient underwent extensive excision of the tumor. Pathologic examinations confirmed the diagnosis of PVNS. The histopathology (Picture 3) demonstrated a diffuse-type giant cell tumor with a nodular appearance and an infiltrative border into the adipose tissue (red