A 6-year-old girl presents with signs of raised intracranial pressure. MRI shows a mass filling the fourth ventricle. Histology shows uniform small cells forming perivascular pseudorosettes, with tumor cell processes radiating toward vessel walls. What is the diagnosis?
- A Medulloblastoma
- B Ependymoma ✓
- C Pilocytic astrocytoma
- D Choroid plexus papilloma
Correct answer: B. Ependymoma
Explanation
Perivascular pseudorosettes are the hallmark of ependymoma, arising from ependymal cells lining the ventricular system; in children the fourth ventricle is the classic site. True ependymal rosettes (cells arranged around a central lumen) may also be seen. Medulloblastoma shows Homer Wright rosettes and small round blue cells without perivascular arrangement. Pilocytic astrocytoma shows Rosenthal fibers and biphasic architecture, while choroid plexus papilloma mimics normal choroid plexus papillary architecture.
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.