Intraarticular calcifying aponeurotic fibroma of the wrist: mimicking gout or calcium pyrophosphate dihydrate deposition disease

Calcifying aponeurotic fibroma is a rare, benign fibroblastic tumor that typically occurs in the palms of the hands and soles of the feet in children and adolescents. We report an unusual case of a calcifying aponeurotic fibroma with diffuse intra-articular involvement of the carpal joints in a 59-year-old female. Radiographs and computed tomography scans revealed a large lobulated soft tissue mass with multiple stippled calcifications around the carpal joints and numerous erosions of the second to fifth carpometacarpal and intercarpal joints. Magnetic resonance imaging showed diffuse multinodular synovial proliferation with inhomogeneous hypo- to isointense signal intensity on T1-weighted images, inhomogeneous hypointense to hyperintense signal intensity on T2-weighted images, and inhomogeneous intense enhancement on fat-suppressed contrast-enhanced T1-weighted images. Radiologic diagnosis included gout, calcium pyrophosphate dihydrate deposition disease, and tenosynovial giant cell tumor. Surgical excision was performed, and the mass was diagnosed on pathologic examination as a calcifying aponeurotic fibroma. There has been no reported case of a calcifying aponeurotic fibroma with diffuse intra-articular involvement of the carpal joints in the literature.