Rosenthal fiber

Rosenthal fibers are brightly eosinophilic, corkscrew-shaped astrocytic inclusions composed primarily of glial fibrillary acidic protein (GFAP) with small heat-shock proteins.

Associated conditions

Rosenthal fibers are found on staining of brain tissue in the presence of long-standing reactive gliosis, some tumors, and rarely in lysosomal storage diseases such as fucosidosis. They are pathognomonic for Alexander disease.
Rosenthal fibers can also be seen in craniopharyngioma.

Composition

The fibers are found in astrocytic processes and are thought to be clumped intermediate filament proteins, primarily glial fibrillary acidic protein. Other reported constituents include alphaB crystallin, heat shock protein 27, ubiquitin, vimentin, plectin, c-Jun, the 20 S proteasome, and synemin.