Superficial Peroneal Nerve Schwannoma.

Schwannomas are benign tumors of the nerve sheath that arise from the proliferation of active peripheral Schwann cells. Although schwannomas are the most common benign peripheral nerve sheath tumors, superficial peroneal nerve schwannomas are rare in published works of literature. We report a 45-year-old woman with a 4-year history of progressively worsening dull aching pain and paresthesia over the right lateral leg. Physical examination revealed a 4 × 3 cm firm palpable mass and a decreased touch and pain sensation over the lateral aspect of the right calf and dorsum of the foot. She also had an electric shock-like pain on palpation and percussion of the mass. Magnetic resonance imaging demonstrated a well-defined, oval, smooth-walled heterogeneous lesion beneath the peroneus muscle with avid postcontrast enhancement and a split fat sign. Fine needle aspiration cytology also suggested the diagnosis of schwannoma. Based on clinical findings of a mass, decreased sensation, and a positive Tinel sign on the dermatome of superficial peroneal nerve, surgical management was decided. Upon surgical exploration, a firm, glistening mass arising from the superficial peroneal nerve was identified, carefully dissected, and shelled out while maintaining continuity of the nerve. At the 5-month follow-up, the patient reported complete resolution of the pain and paresthesia. Physical examination revealed intact sensation in the lower lateral aspect of the right calf and dorsum of the foot. Therefore, surgical excision should be considered a reasonable option in the management of this rare condition, with most patients achieving good to excellent results.