Soft-Tissue Benign Mesenchymoma in a Pediatric Patient

Soft tissue mesenchymoma is an exceptionally rare and benign neoplasm. Since its initial description in 1962, only 7 cases of cartilage predominant appendicular mesenchymoma have been reported. Of these, only 2 patients were skeletally immature. We report the clinical, pathologic, and radiologic features of a 13-year-old adolescent boy with a benign mesenchymoma in the distal leg.