Primary clear cell sarcoma of the calcaneus : Report of a rare case and review of the literature.

Clear cell sarcoma (CCS) is a rare soft tissue tumor derived from neural crest cells. It accounts for 1% of all soft tissue sarcomas and usually involves the tendons and aponeuroses in the distal ends of the extremities. The foot and the ankle are the most common primary sites. A CCS predominantly occurs in young adults and has rarely been reported in children and older people. On magnetic resonance imaging the tumor has a benign appearance. It appears isointense, hypointense or slightly hyperintense on T1-weighted images. A CCS is typically strongly positive for HMB-45, S‑100, melanA, MITF and vimentin on immunohistochemical investigations and exhibits the t(12;22)(q13;q12) translocation on cytogenetic studies. Metastasis occurs mainly to the regional lymph nodes. A tumor size ≥5 cm is invariably associated with a poor prognosis. The main treatment is wide excision but local recurrence and distant metastases are common. This article presents the case of a 61-year-old man with right ankle tenderness and malaise. Ultrasound-guided biopsy and pathological examination were performed and the pathological diagnosis was a CCS. The patient underwent a below-knee amputation and had no local recurrence or metastasis at the 6‑month follow-up.