Abstract
Schwannoma is a benign tumor derived from Schwann cells that cover myelinated nerve fibers (1). Among primary bone tumors, intraosseous schwannoma accounts for less than 0.2% (2). We are reporting a rare case of an 18-year-old female presented with swelling in the posterior right thigh. The patient was asymptomatic and this was incidentally discovered by her massage therapist. However, the swelling was gradually growing since then. The plain radiograph findings were suggestive of a benign bone tumor. MRI with gadolinium was performed for further evaluation but it demonstrated suspicious features as evidenced by the extra osseous enhancing soft tissue component. Three phase bone scan was done thereafter and it showed hyperemia with mild increased uptake of the lesion on the delayed phase. Osteosarcoma was suspected and chest CT was performed for staging purposes which turned out to be negative for metastasis. The lesion was biopsied under ultrasound guidance. The histologic features and the immunohistochemically profile were consistent with a benign schwannoma. The posterior thigh soft tissue mass was surgically resected with femur bone grafting. Recurrence of schwannoma should be considered but its malignant transformation is exceedingly rare and this can be discounted (3).