Intraneural perineurioma of the sciatic nerve in early childhood.

Intraneural perineurioma is an uncommon benign neoplasm characterized by focal perineural cell proliferation. The typical course is indolent, with gradual onset and slow progression of motor loss. In early childhood, uncertainty concerning the time of onset can lead to difficulty in distinguishing this potential treatable lesion from congenital and other causes of nerve palsy. In the present case, clinical presentation, electrophysiologic findings, and magnetic resonance imaging findings in a child were compatible with intraneural perineurioma of the lumbosacral trunk and sciatic nerve. Initially, peroneal neuropathy was suspected. The case illustrates that sciatic intraneural perineuriomas do occur in early childhood, and that traction on the sciatic nerve may result in earlier damage to the peroneal nerve than to the tibial nerve, thus mimicking a more peripheral lesion.