Tibial Nerve Schwannoma: An Unexplained Cause of Lateral Foot Pain - A Rare Case Report and Review.

Introduction: Schwannoma is a benign tumor that arises from the peripheral nerve sheath. It presents as a discrete, often tender, and palpable nodule associated with neurogenic pain or paresthesia when compressed or traumatized. The growth rate is usually slow, and these lesions seldom exceed 2 cm in diameter.

Case Report: We report the case of a schwannoma arising from the tibial nerve located in the left popliteal fossa. The patient presented with the left foot pain in the lateral plantar region without any motor deficit. The pre-operative diagnosis was made with magnetic resonance imaging (MRI) scan. He was subjected for neurolysis and excision biopsy of the lesion. The surgical specimen consisted of encapsulated white-yellow mass with irregular contours, measuring 2 × 3 cm. The cut section revealed cystic degenerations with areas of hemorrhage and necrosis. The patient reported symptom free in the post-operative period and during follow-up. Marginal excision appears to be recommended therapy for this tumorous lesion, without any evidence of recurrence during follow-up.

Conclusion: A benign nerve sheath tumor of a peripheral nerve could be a possibility for long-standing neuropathic pain in the foot, ankle, and leg, wherein all other possibilities have been ruled out. The meticulous examination of the entire length of the tibial nerve including sciatic nerve by palpation and percussion was helpful in diagnosis which should be confirmed by MRI scan. The excision biopsy remains the gold standard treatment of choice for schwannoma of the peripheral nerve.