A 5-year-old boy presents with morning headache and truncal ataxia. MRI reveals a posterior fossa mass compressing the fourth ventricle. Biopsy shows small round blue cells with Homer Wright rosets. Which molecular subgroup of this tumor portends the most favorable prognosis?
- A WNT activation ✓
- B SHH activation
- C MYC amplification
- D Group 3
Correct answer: A. WNT activation
Explanation
The biopsy shows a medulloblastoma. WNT-activated medulloblastomas have the best prognosis, often presenting with classic histology and arising near the brainstem or cerebellar peduncle. Group 3 tumors and those with MYC amplification have the worst prognosis. SHH-activated tumors have an intermediate prognosis.
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.