Anteromedial Knee Pain Unmasked: Schwannoma of the Infrapatellar Branch of the Saphenous Nerve - A Rare Case Report.

INTRODUCTION

Schwannomas are benign, encapsulated peripheral nerve sheath tumors derived from Schwann cells. They are rarely seen around the knee, accounting for <1% of all schwannomas, and can mimic other benign swellings such as ganglion cysts or bursae.

CASE REPORT: We report a 32-year-old female who presented with anteromedial right knee pain and a tender swelling for 2 years. Radiographs were normal, and a provisional diagnosis of a ganglion cyst was made. The lesion was excised under local anesthesia through a vertical incision and found to be a well-encapsulated mass measuring approximately 1 × 1 × 1 cm, located superficial to the joint capsule. Based on its location, the swelling was suspected to arise from a branch of the saphenous nerve, most likely the infrapatellar branch. Histopathological examination confirmed the diagnosis of schwannoma.

CONCLUSION

Schwannomas, though benign and uncommon around the knee, should be included in the differential diagnosis of localized knee pain with soft-tissue swelling and normal radiographs.