Isolated peripheral neurilemoma attached to the tendon of the flexor digitorum longus muscle.

Neurilemomas are benign tumours arising from peripheral nerves with a Schwann cell sheath. They are normally painless and slowly growing, rarely causing motor disturbances. Neurilemomas are most common in the cranial nerves, in the trunk, the upper and lower extremities, but may appear anywhere. Especially rare are neurilemomas of the lateral peroneal nerve in the region of the fibular head and in the foot. We present the first detailed report of a neurilemoma localized between the Achilles tendon and the flexor digitorum longus muscle with separation of the tumour from the tibial nerve.