Intra-articular synovial sarcoma in the ankle joint: A case report.

Intra-articular primary soft tissue sarcomas are extremely rare. The present case report describes a case of intra-articular synovial sarcoma of the ankle joint. A 51-year-old man presented with complaints of swelling and progressive pain in the right ankle. Lateral radiographs of the ankle revealed lytic invasion of the anterior and posterior parts of the talus. Computed tomography imaging revealed a low-density lesion with calcifications around the ankle joint. Magnetic resonance imaging revealed that the diffuse lesion was isointense on T1-weighted images and hypointense to hyperintense on T2-weighted images. The final diagnosis was synovial sarcoma. The foot could not be salvaged as the sarcoma was diffusely spread throughout the ankle joint; thus, the patient underwent below-the-knee amputation with neoadjuvant and adjuvant chemotherapy. He succumbed from fatal arrhythmia 2 years following the initial diagnosis. Although intra-articular primary soft tissue sarcomas are extremely rare, the possibility of malignancy should be considered.