Schwann cell proliferation as the cause of peripheral neuropathy in neurofibromatosis-2.

We report a 18-year-old man who developed slowly progressing right drop foot. Bilateral acoustic neurinoma was found and he was diagnosed as neurofibromatosis-2. Right sural nerve biopsy showed multiple small onion-bulb-like structures in the nerve fascicle. Electronmicroscopic and immunohistochemical studies on this structure confirmed cytological characteristics of Schwann cells, while previous reports suggest that this structure originates from perineural cells. The present report is the first to show both ultrastructurally and immunohistochemically that the onion-bulb-like structure is derived from Schwann cell.