Widespread occurrence of eosinophilic neuronal cytoplasmic inclusions in an asymptomatic adult: a novel ubiquitin-negative filamentous inclusion.

We describe a 67-year-old woman without apparent neurological symptoms, in whom postmortem examination revealed widespread occurrence of eosinophilic neuronal cytoplasmic inclusions in the central and peripheral nervous systems. The inclusions were round, oval or rod-like in shape. Immunohistochemically, the inclusions were negative for ubiquitin and not labeled with any other antibodies, except for a partial and weak immunoreactivity with anti-neurofilament occurring rarely. Ultrastructurally, the inclusions revealed two different forms. The common form was entirely composed of bundles of wavy granule-coated filaments (20–30 nm in diameter). The other form consisted of a core containing linear filaments (12–15 nm in diameter) with electron-dense ribosome-like granules and an outer zone with wavy filaments as seen in the former. This inclusion seems to represent a new type of neuronal cytoplasmic inclusion.