Nonviral Intranuclear Filamentous Inclusions

Intranuclear filamentous structures have been found in cells of both central and peripheral nervous tissues in eight patients with a variety of neurologic diseases. The structures were curly, fibrillary strands, resembling paramyxoviral filaments morphologically, but larger in diameter (25 to 40nm). Their appearance was granular with indistinct, hazy outlines, and on cross section they were solid rather than tubular. These structures are probably not viral but chromatin fibers. The illustration of sequential development of the fibrillary structures from usual chromatin clumps supports this view. Thus, the finding of intranuclear fibrillary material in the cells of a number of patients with neurologic diseases must be interpreted with caution.