10 year old child with posterior fossa mass. On biopsy following features were seen. What are these dense eosinophilic fibers marked with arrow?: (A) Rosenthal fibers, (B) The Alzheimer type II astrocyte, (C) Corpora amylacea, (D) None
Answer is A. Ans. (a) Rosenthal fibers*Rosenthal fibers are eosinophilic, corkscrew fibers found in pilocytic astrocytoma, the most common primary brain tumor in children. They contain two heat-shock proteins (aB-crystallin and hsp27) as well as ubiquitin.*They are seen in Alexander disease and, pilocytic astrocytoma.