Posterior Tibial Nerve Lymphoma Presenting as Tarsal Tunnel Syndrome: A Case Report

We report a case of isolated posterior tibial B-cell lymphoma of the posterior tibial nerve presenting as tarsal tunnel syndrome. This diagnosis was considered because of the clinical presentation and electrophysiologic abnormalities. It was further confirmed by the magnetic resonance imaging findings of the ankle and tissue pathologic findings. Whole body positron emission tomography confirmed this to be a localized lymphoma involving the peripheral nerve. The patient underwent chemotherapy with complete tumor resolution. She had had no relapse after 8 months of follow-up. Isolated peripheral nerve lymphomas are very rare, and involvement of the posterior tibial nerve has not been previously reported. Furthermore, the present case report highlights the importance of the clinical examination in the diagnosis of tarsal tunnel syndrome before performing surgical decompression.