QUIZ: No. 31, 18/10/2025

QUIZ No. 31

ANS – IDH-wild-type glioblastoma (CNS WHO Grade 4)

Findings: Well-circumscribed peripheral thick nodular enhancing, T2 heterogeneously hyperintense, FLAIR heterogeneously hyperintense and T1 iso- to hypointense solid lesion with a cystic component in the deep anterior interventricular region, anterosuperior to the third ventricle. The lesion demonstrates intense diffusion restriction with surrounding vasogenic edema involving the corpus callosum and right caudate head, with mild effacement of the frontal horn of the right lateral ventricle and mass effect on the left foramen of Monro, resulting in mild left ventricular prominence. No calcifications, hemorrhage, or intraventricular extension are seen. MR spectroscopy shows elevated choline and reduced NAA, consistent with a high-grade glioma.

Glioblastoma and astrocytoma are both brain tumors that come from astrocyte cells, but they are not the same. Glioblastoma is the most aggressive type and is always IDH-wildtype, classified as Grade 4 and has a poor prognosis.

Imaging Features Suggesting IDH-Wild-Type Glioma

1. Deep or midline location (corpus callosum, basal ganglia).

2. Irregular, infiltrative margins crossing midline.

3. Heterogeneous/ring enhancement with necrosis.

4. Extensive peritumoral edema.

5. High rCBV, low ADC.

6. Elevated choline, lipid–lactate peaks on MRS.

Take home points - Not all smaller lesions are benign.

·  Even small, well-circumscribed brain lesions can represent high-grade or aggressive pathology, especially when located deep, midline, or showing disproportionate diffusion restriction, enhancement, or edema.

P.S – Patient underwent right frontoparietal craniotomy and surgical excision. HPE and IHHC confirmed high-grade glioblastoma with: IDH-1 negative, ATRX retained, p53 positive, Ki-67 = 20–25% and MGMT promoter methylated