A 6-year-old child presents with raised intracranial pressure. Imaging shows a mass filling the fourth ventricle. Histology shows tumor cells arranged around blood vessels with nuclei displaced away from the vessel wall and an anuclear zone between the vessel and nuclei. This pattern is characteristic of:

• A Pilocytic astrocytoma
• B Choroid plexus papilloma
• C Ependymoma ✓
• D Atypical teratoid rhabdoid tumor

Explanation

The description is of perivascular pseudorosettes, the hallmark of ependymoma, a tumor of ependymal cells that typically arises in the fourth ventricle in children and causes obstructive hydrocephalus. True rosettes around a central lumen (rosettes of Flexner-Wintersteiner type) may also be seen. Homer Wright rosettes of medulloblastoma surround a central fibrillar core rather than a vessel, killing option A.

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.