Tip-31;Pilocytic-astrocytoma of an Adult

Tip-31; Pilocytic astrocytoma is a grade-1 circumscribed astrocytoma, that is most commonly seen in the posterior fossa in children. It is a biphasic tumor with compact and loose or myxoid regions, composed of bipolar hair-like/ pilocytic cells, with scattered Rosenthal fibers ( in the piloid areas), and eosinophilic granular bodies (in the loose/ cystic areas). Pilocytic astrocytoma is associated with MAPK pathway gene alterations, most often KIAA1549::BRAF gene fusions in the posterior fossa.