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Primary CNS lymphoma — SCE Neurology MCQ

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HardNeuro-oncologyPrimary CNS lymphomaSCE Neurology

A 67-year-old immunocompetent man has subacute confusion and right hemiparesis. MRI shows a homogeneously enhancing periventricular mass crossing the corpus callosum with marked diffusion restriction but relatively little necrosis. Symptoms briefly improved after dexamethasone given for oedema. What is the most likely diagnosis?

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Correct answer: C — Primary CNS lymphoma

Primary CNS lymphoma is the best answer. A periventricular homogeneously enhancing diffusion-restricting lesion with steroid responsiveness is typical of primary CNS lymphoma. Glioblastoma is usually necrotic and heterogeneous; abscess has infectious context; metastases are often multiple at grey-white junction; tumefactive MS has demyelinating features and open-ring enhancement. Clinical pearl: Steroids can reduce biopsy yield in suspected CNS lymphoma, so early neurosurgical discussion is important.

Reference: EANO primary CNS lymphoma guideline; NICE brain tumour guidance