Intracisternal inclusions in Schwann cells of the sural nerve.

Biopsy of the sural nerve in a 74-year-old man with chronic neuropathy demonstrated Schwann cells that possessed multiple cisterns of rough endoplasmic reticulum filled with 7- to 8-nm filaments and perinuclear cisterns that were markedly distended with fine granular substances and electron-dense globules. To our knowledge, this is the third case exhibiting filamentous inclusions in Schwann cells. Unlike the previous cases, however, this case showed inclusions in the distended perinuclear cisterns and axonal degeneration. The significance of these alterations remains to be elucidated.