CD34 staining is typically negative in tumor cells and highlights vasculature, a feature that differentiates PA from glioneuronal tumors, such as
ganglioglioma. Where available, pERK staining is often correlated with the presence of MAPK pathway activation that, in turn, is often associated with typical BRAF duplication (11).
In their study, one case of
ganglioglioma was proved by GFAP application, in which ganglion cell like astrocytes were differentiated from neoplastic neurons by positive expression for the antibody.
Differential diagnosis includes arachnoid cyst, porencephalic cyst, dermoid/epidermoid cyst, low grade cystic neoplasm (eg,
ganglioglioma, DNET), and parasitic cyst (eg, hydatid disease).
Identification of the IDH1 R132H protein in otherwise uncharacteristic tissue can help establish a diagnosis of diffuse glioma, and exclude the possibility of other (morphologically similar, in a limited tissue sample) entities, such as
ganglioglioma (33) or nonneoplastic conditions (inflammation or infection).
The dense cellularity and pleomorphism raises a possibility of
ganglioglioma and higher grade malignancies like glioblastoma, giant cell glioblastoma, gliosarcoma or even pleomorphic sarcoma.
Differential diagnoses for this patient included choroid plexus papilloma, angiomatous meningioma, and
ganglioglioma. Choroid plexus papilloma was excluded based on immunostaining for neuronal markers and a lack of focal cytokeratin expression.
Meyer et al., "Analysis of BRAF V600E mutation in 1,320 nervous system tumors reveals high mutation frequencies in pleomorphic xanthoastrocytoma,
ganglioglioma and extra-cerebellar pilocytic astrocytoma," Acta Neuropathologica, vol.
Ganglioglioma (GG), a rare glial-neuronal brain tumor characterized by dysplastic ganglion cells and neoplastic glial cells, accounts for about 0.4% of all tumors arising in the central nervous system (CNS) [5].
Collectively the morphologic features and immunophenotype confirmed the diagnosis of
ganglioglioma, despite the lesion's unusual location.
The neurosurgical biopsy revealed a low grade
ganglioglioma, so neither chemotherapy nor radiotherapy were proposed.
Kadapakkam et al., "Constitutional tandem duplication of 9q34 that truncates EHMT1 in a child with
ganglioglioma," Pediatric Blood & Cancer, vol.