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CIS – McDonald Criteria 2017 — SCE Neurology MCQ

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HardMultiple Sclerosis & CNS InflammationCIS – McDonald Criteria 2017SCE Neurology

A resected infiltrating cerebral glioma is IDH1-mutant and ATRX-deficient, with retained 1p/19q. There is brisk mitotic activity but no necrosis or microvascular proliferation. Molecular testing shows homozygous CDKN2A/B deletion. What is the integrated diagnosis and grade?

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Correct answer: A — Astrocytoma, IDH-mutant, CNS WHO grade 4

Explanation lettering: D = shown as A · A = shown as B · E = shown as D · B = shown as E

A and B undergrade the tumour: homozygous CDKN2A/B deletion is sufficient to assign grade 4 in an IDH-mutant astrocytoma even without necrosis or microvascular proliferation. C is wrong because the tumour is IDH-mutant and ATRX-deficient. D is correct. E requires whole-arm 1p/19q codeletion, which is absent, and would usually retain ATRX. The molecular grade therefore overrides deceptively lower-grade morphology.

Reference: EANO guideline on diffuse gliomas of adulthood: https://pmc.ncbi.nlm.nih.gov/articles/PMC7904519/