Neuronal intranuclear inclusion disease: neuropathologic study of a case.

We report neuropathological findings in a 22-year-old man affected with neuronal intranuclear inclusion disease. The inclusions affected to different extents the various structures of the central nervous system, being more numerous in cerebral cortex, inferior olives, hypoglossal and oculomotor nuclei. They ultrastructurally differed from Marinesco bodies. In the neurons of the substantia nigra, we occasionally observed intranuclear inclusions resembling the so-called rodlets of Roncoroni. We did not observe inclusions in the extraneuronal tissues. There was no apparent correlation between frequency of the inclusions and neuronal loss. Intranuclear inclusions were found in many morphologically normal neurons. We suggest that the intranuclear inclusions are the marker of a distinctive disorder, even though their role in neuronal degeneration remains to be clarified.