{{ https://upload.wikimedia.org/wikipedia/commons/thumb/9/94/Rosenthal_HE_40x.jpg/220px-Rosenthal_HE_40x.jpg}} A Rosenthal fiber is a thick, elongated, worm-like or "corkscrew" eosinophilic (pink) bundle that is found on H&E staining of the brain in the presence of long-standing gliosis, occasional tumors, and some metabolic disorders.