A young man presented with ataxia. Brain contrast enhanced MRI was done including DWI and perfusion. T2WI showed a mixed intensity lesion in the inferior right cerebellar hemisphere which contained some “dark stripes”. DWI ADC map show restricted diffusion centrally. After contrast the lesion enhanced in a striped fashion and perfusion showed low rCBV (see below). Llermitte-Duclos disease was considered in the differential diagnosis.
Further questioning of patient disclosed that the symptoms had had a sudden onset 7 days earlier. The diagnosis of subacute infarction of the right posterior inferior cerebellar artery territory was considered as the most likely cause of the findings. The patient was followed and repeat MRI three months later demonstrated only malacia and atrophy in the location.
Llermitte-Duclos disease (a.k.a. dysplastic gangliocytoma of the cerebellum) is the CNS hallmark of Cowden syndrome. It is probably a malformative hamartoma of the cerebellum seen nearly exclusively in this syndrome. The typical lesion has a “corduroy” or “tiger striped” appearance, does not enhance after contrast, has restricted diffusion (presumably due to its high cellularity), and normal-to-increased perfusion. MRS shows low NAA, decreased Cho/Cr, elevated lactate and high myoinositol and at times the spectra may be near normal (see below). PET shows increased FDG accumulation. Thus to differentiate it from an infarct with similar appearance perfusion and PET studies are best when in doubt. Additionally, contrast enhancement in Llermitte-Duclos is extremely rare.
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