Intraneural neurofibromas involving the posterior interosseous nerve.

Two patients presented with a posterior interosseous nerve palsy with supinator weakness. In each case an intraneural neurofibroma was found proximal to the supinator tunnel with no other stigmata of von Recklinghausen's disease. Both tumours showed a whorl-like histological pattern that has been previously confused with onion-bulb structures in hypertrophic polyneuropathy. Electron-microscopy was useful for the pathological diagnosis. The prognosis and treatment of the lesions are discussed.