Tarsal tunnel syndrome associated with a neurilemoma in posterior tibial nerve: a case report.

Compression neuropathy of the posterior tibial nerve (PTN) and its branches in the tarsal tunnel is called tarsal tunnel syndrome (TTS) and has various aetiologies. Space-occupying lesions in the tunnel, such as neurilemomas, can cause such a disease. When a neurilemoma occupies the tarsal tunnel, it can compress the PTN directly or indirectly and results in restriction of the tunnel volume. Symptoms due to this restricted volume may vary in TTS. A case of neurilemoma of PTN in tarsal tunnel with a complaint of posteromedial ankle intermittent pain in a 20-year-old patient is presented here. A mass was observed at the ankle posteromedially during clinical examinations and the patient underwent magnetic resonance imaging (MRI) and radiological investigation. Radiographic evaluation of the ankle was normal. However, MRI was revealed a mass adjacent to the PTN in the tarsal tunnel. An ovoid, smooth-surfaced, encapsulated and eccentrically localized mass in the PTN was detected at surgery. The mass was excised from the nerve and pathological evaluation revealed a neurilemoma (schwannoma). Neurilemomas arising from the PTN in the tarsal tunnel should always be kept in mind as a differential diagnosis when a patient complains of a posteromedial ankle pain. Since it is a space-occupying lesion and encapsulated tumor in the tarsal tunnel, simple surgical resection is curative without a distinct morbidity.