Ganglioglioma and Gangliocytoma

Ganglioglioma and Gangliocytoma

Ganglioglioma: comprises a mixed population of mature neurons ("ganglio-") and glial cells (-"glioma"). Thus, immunochemistry will stain the neuronal component (synaptophysin, chromogranin, neurofilament, etc...) and the glial component (GFAP).
Gangliocytoma: purely comprises mature neurons.
Because of their neuronal origin, these tumors stain neuronal markers (synaptophysin, MAP-2, neurofilament, NeuN, etc...).

Classically present as a temporal lobe tumor in patients < 20 yo with a long-standing history of epilepsy.

Typically these are benign, slow-growing tumors, thus they can have long-standing symptoms before they are identified.

On radiographic imaging, they are classically cystic with a mural nodule (think: pilocytic astrocytoma) but can also be a circumscribed/solid variably enhancing mass that expands the gyrus and causes thinning of the overlying bone.
On histopathology, there is characteristically a fibrillary background with abnormal ganglion cells but other features are also common, including, notably: eosiniphilic granular bodies (commonly seen in pilocytic astrocytoma).
Ganglioglioma is different than dysembryoplastic neuroepithelial tumor (DNET) and desmoplastic infantile astrocytoma and ganglioglioma.

References

Adesina, Adekunle M., Tarik Tihan, Christine E. Fuller, and Tina Young Poussaint. Atlas of Pediatric Brain Tumors. Springer, 2016.

Gray, Frangoise, Charles Duyckaerts, and Umberto De Girolami. Escourolle and Poirier’s Manual of Basic Neuropathology. OUP USA, 2013.

Tonn, Jörg-Christian, Manfred Westphal, and J. T. Rutka. Oncology of CNS Tumors. Springer Science & Business Media, 2010.

Yachnis, Anthony T., and Marie L. Rivera-Zengotita. Neuropathology E-Book: A Volume in the High Yield Pathology Series. Elsevier Health Sciences, 2012.