Polyneuropathy with lipid deposits in Schwann cells and axonal degeneration in cerebrotendinous xanthomatosis.

The present paper is a histological, histochemical and electron microscopic study of biopsied specimens from both right and left Achilles tendon, sural nerve and gastrocnemius muscle in a case of peripheral neuropathy with decreased sensory conduction velocity within a cerebrotendinous xanthomatosis confirmed biochemically in a 29-year-old woman. The tendon specimens contained large deposits of complex, non-homogeneous lipids, distributed intra- and extracellularly. The right sural nerve specimen showed a very severe neuropathy with massive diffuse myelinated fiber loss, presence of foamy macrophages and lipid droplets in Schwann cells. Segmental de- and remyelination was noted in 17% of the teased myelinated fibers. No onion bulbs were observed. Two years later, the left sural nerve specimen revealed a mild diffuse myelinated fiber loss, a more active segmental de- and remyelination (23%) without onion bulbs, and an active regeneration. Lipid storage aspects were absent. The gastrocnemius muscle specimens exhibited slight alterations of neurogenic origin. The pathogenesis of this neuropathy is discussed.