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Multiple sclerosis pathology — MRCPsych Paper A MCQ

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ModerateNeuropathologyMultiple sclerosis pathologyMRCPsych Paper A

A 32-year-old woman has experienced two episodes of optic neuritis separated by 18 months, with partial recovery after each episode. She subsequently reports low mood and cognitive fatigue. MRI shows multiple ovoid periventricular white-matter lesions, including lesions orientated perpendicular to the lateral ventricles. Which neuropathological finding is most likely?

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Correct answer: C — Perivenular plaques showing myelin loss, macrophage-rich inflammation and relative axonal preservation

The correct answer is C. Recurrent neurological episodes separated in time, optic neuritis and ovoid periventricular lesions orientated perpendicular to the ventricles are characteristic of multiple sclerosis. Its pathological hallmark is inflammatory CNS demyelination: active perivenular plaques contain lymphocytes and myelin-laden macrophages, with relative preservation of axons early in lesion evolution. Lewy bodies indicate a synucleinopathy such as dementia with Lewy bodies. Striatal neuronal loss and mutant huntingtin inclusions occur in Huntington disease. Copper deposition involving the basal ganglia occurs in Wilson disease, usually alongside hepatic or other systemic evidence. Beta-amyloid plaques and tau neurofibrillary tangles are characteristic of Alzheimer disease. Low mood and cognitive fatigue can accompany multiple sclerosis but are not themselves pathognomonic.

Reference: Rushing EJ, et al. Multiple sclerosis: a practical review for pathologists. Journal of Pathology and Translational Medicine. 2025. https://pubmed.ncbi.nlm.nih.gov/40574276/