Synovial chondromatosis of the foot presenting with Lisfranc dislocation.

Primary synovial chondromatosis is rare in the foot. We report a case of synovial chondromatosis affecting multiple sites of the foot and causing bone erosions in a 44-year-old woman. Radiographs demonstrated erosions of multiple metatarsals including the tarsometatarsal joints, resulting in Lisfranc tarsometatarsal dislocation. Magnetic resonance imaging showed the widespread synovial proliferation and soft tissue masses affecting the foot and helped in arriving at a differential diagnosis and plan for needle biopsy. Diagnosis was made initially by needle biopsy under computed tomography guidance and was subsequently confirmed by histopathological assessment of the surgically excised synovial masses. To our knowledge, multifocal synovial chondromatosis causing Lisfranc dislocation in the foot has not been reported previously.