Presentation
Intractable seizures.
Patient Data
A lesion comprising of a cluster of cortical and subcortical cysts in the right inferior subcentral gyrus and operculum demonstrate no enhancement and no calcification or blood products. The cysts attenuate fully on FLAIR but are embedded in a region of increased T2 signal. Diffusion demonstrates facilitated diffusion of both the presumed fluid component and the intervening tissue.
The differential diagnosis is primarily between a low-grade tumor (DNET, gangliocytoma, ganglioglioma) and a cluster of perivascular cysts. The presence of intractable seizures favors the former.
An MVNT is a possibility although the cysts are usually smaller and do not attenuate on FLAIR.
Case Discussion
The patient went on to have a resection.
Histology
The cortex is hypercellular containing abnormal disordered neurons with large ovoid nuclei, vesicular chromatin and conspicuous nucleoli. No mitoses are seen. Away from these areas, there are hemosiderin laden macrophages associated with perivascular chronic inflammation. By immunohistochemistry, these cells are positive for NeuN and ATRX (non-mutated) and negative for IDH1 (non-mutated), GFAP, p16, p53 and BRAF V600E. Ki 67 is <1%.
FINAL DIAGNOSIS: gangliocytoma (WHO Grade I).