Ganglioglioma

Final Diagnosis:

Consistent with a ganglioglioma

Micro Examination:

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 neuroeipithelial 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.