A 45-year-old man presents with progressive ataxia and headache. MRI shows a cystic lesion in the cerebellum with an enhancing mural nodule. Histology shows a biphasic tumor with loose microcystic areas and compact piloid cells containing Rosenthal fibers. Which of the following is the most likely diagnosis?
- A Hemangioblastoma
- B Medulloblastoma
- C Pilocytic astrocytoma ✓
- D Ependymoma
Correct answer: C. Pilocytic astrocytoma
Explanation
Pilocytic astrocytoma (CNS WHO grade 1) classically presents as a cerebellar cystic mass with an enhancing mural nodule in children and young adults. Histology shows a biphasic pattern with loose microcystic areas and compact piloid cells containing Rosenthal fibers and eosinophilic granular bodies. Hemangioblastoma also presents as a cystic cerebellar mass with a mural nodule but shows foamy stromal cells and is associated with VHL. Medulloblastoma is a solid small round blue cell tumor. Ependymoma shows perivascular pseudorosettes.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.