[Peripheral nerve changes in Tangier disease. Comparative light-, electron-microscopic and cytometric studies...

A sural nerve biopsy was performed in a 55-year-old male patient with Tangier disease (familial-lipoprotein deficiency). Light-microscopy showed an increase in the endoneural connective tissue and a loss of nerve fibers indicating a chronic peripheral neuropathy. Electron-microscopy revealed an accumulation of lipid droplets within Schwann cells of myelinated and unmyelinated nerve fibers. When compared with age-matched controls the myelinated fiber density was reduced with a relative preponderance of small myelinated fibers. In addition, distributional cytometric studies of nerve fibers in relation to the perineurium and endoneurial capillaries showed: Contrary to 4.6-7.5 micron thick nerve fibers, which accumulated in the center of the nerve fascicle, small (0.5-4.5 micron) and large (7.6-10.0 micron) fibers lay nearby the perineurium. The measured increase in small myelinated nerve fibers around endoneurial capillaries may be explained as a sign of regeneration.