Giant Schwannoma of the Saphenous Nerve in The Distal Thigh: A Case Report.

Case: Schwannomas are benign nerve myelin sheath tumors that can occur anywhere in the peripheral nervous system. It is very rare for Schwannomas to become malignant, but surgery is still the principal treatment to eliminate symptoms and to correctly diagnosis the tumor. We report an interesting case of a schwannoma of the saphenous nerve at the distal third of the posteromedial thigh: the patient complained of muscle weakness at left lower limb and vague anteromedial knee pain, mimicking a meniscal tear. Magnetic resonance images of the thigh showed a well-defined and oval mass lesion measuring 8.5 cm x 4.5 cm. Before investigating for a possible meniscal tear, we decided to remove the mass from the thigh, because we felt that it could itself be the cause of the mild pain complained about by the patient. Post-surgery, histological analysis conducted confirmed that this was a benign schwannoma.

Discussion: Schwannomas generally can be asymptomatic or present as a mass. The clinical presentation of this rare tumor makes the diagnosis difficult.

Conclusion: This reported case is particularly interesting because of the rarity of the lesion localization along the course of the saphenous nerve. The combination of the location, and especially the large size of the tumor, led us to believe that there is a correlation with the particular clinical presentation.