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Selected MRI images showing a juxtacortical small cystic lesion in the left frontal lobe that shows partial suppression on FLAIR.
The patient underwent to surgery and the pathology study confirmed a ganglioglioma.
Histology: Sections of "wall of cyst + surrounding tissue" show a tumour comprised of cells predominantly with round nuclei with mild-to-moderate degree of pleomorphism. Some of these cells have perinuclear halos. In some regions, there are microcysts. And, in some of these cysts, free-floating neurons are seen. Scattered neurons throughout the lesions show somewhat peculiar shapes and are maloriented. Immunocytochemistry shows that many of these small round nuclei are positive for GFAP. However, many cells are also negative for GFAP. Staining for phosphorylatyed neurofilament shows rare positive neuronal cell bodies. Staining for synaptophysin shows rare positivity of neuronal cell bodies. Several neurons show positivity for chromogranin. Within the section where there are microcystic areas with free-floating neurons, many of the small glial cells associated with cysts are GFAP-positive, and only rare cells are GFAP-negative. No mitotic activity is seen. There is no endothelial proliferation and there is no necrosis.
Comments: The histological appearance of the tumour is that of a glial-neuronal tumour. The dysplastic nature of the neurons and their chromogranin positivity favours the diagnosis of ganglioglioma. Whereas there are areas which superficially resemble the so-called "glial neuronal element" of dysembryoplastic neuroepithelial tumour (for example in "M"), the fact that many of the small cells in this area are GFAP-positive and that the neurons show dysplastic features, makes that diagnosis less likely.