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Rosenthal fibers and glial filaments associated with hemidesmosome‐like structures in perivascular astrocytes in a juvenile form of Alexander's disease

We present a rare case of Alexander's disease occurring in a 10–year‐old girl with convulsive seizures. She initially developed gait disturbance and thereafter deteriorated mentally. At 48 years of age she died of cumulative convulsive seizures. The postmortem examination revealed a generalized and focally pronounced deposition of Rosenthal fibers in the deep cerebral white matter around the lateral ventricles. Atypical fibrillary glia, diffuse patchy demyelination and circumscribed cystic necrosis were also observed. An electron microscopic examination of the cerebral white matter revealed not only irregular, densely osmiophilic bodies merging in places with glial filaments, but also well‐developed hemidesmosomes associated with anchorage densities in the perivascular astrocytes. The subplasmalemmal anchorage densities usually received glial fibrils, which were frequently intermingled with Rosenthal fibers. Thus, our case can be added to the small number of previously reported cases demonstrating a juvenile form of Alexander's disease based on both clinicopathologic features and on ultrastructural appearance, and our case also confirms the profound involvement of astrocytes.