Ganglioglioma - occipital lobe

Case Discussion

Final Diagnosis:

Specimen labeled "brain tumor": Consistent with ganglioglioma.

The peculiar large cells in this lesion are consistent with atypical neurons alough some are positive for GFAP. The histological features are most consistent with a ganglioglioma.

Microscopic Description:

Sections show a tumor comprised of two cell types. The first is a relatively small nucleus with round to elongated shapes showing thin process formation. The second are large bizarre cells with prominent cytoplasm, in some cases the basophilic and other cases showing eosinophilic granular appearance. Many of the latter cells show large bizarre nuclei some with pseudonuclear cytoplasmic inclusions. Occasional eosinophilic granular bodies are present. No mitotic activity is seen. There is no endothelial proliferation and there is no necrosis.

Immunohistochemistry shows that many of the small cells are positive for glial fibrillary acidic protein (GFAP). Some, but not all, of the large bizarre cells are positive for GFAP. Immunohistochemistry for phosphorylated neurofilament shows background parenchyma in the form of numerous axons. The parenchyma is also evident on the synaptophysin stain and some of the large cells are positive for synaptophysin. The Bielschowsky stain shows axons within the tumor and no intracytoplasmic silver positive inclusions are evident. The reticulin stain shows occasional linear focal positivity at the periphery of some of the large cells, but this is also evident in the background of the section.

The tumor is negative for epithelial membrane antigen. p53-positive cells are present. Very few cells are positive for the cell proliferation marker MIB-1.