Not All Monstrous Cells Indicate Glioblastoma: A Neuropathological Case Report of Pleomorphic Xanthoastrocytoma Misdiagnoses As Giant Cell Glioblastoma.

Pleomorphic xanthoastrocytoma (PXA) is a rare central nervous system malignant neoplasm with a relatively favorable prognosis. As PXA histologically presents with large, multinucleated neoplastic cells, its principal differential diagnosis is giant cell glioblastoma (GCGBM). While there is a significant overlap between the two histologically and the neuropathological diagnosis can be challenging, as well as having some overlap neuroradiologically, the patient prognosis differs significantly, with PXA having a more favorable one. Herein we present a case report of a male patient in his thirties diagnosed with GCGBM and presenting again six years later with thickening of the wall of the porencephalic cyst suggestive of disease recurrence. Histopathology revealed neoplastic spindle, small lymphocyte-like, large epithelioid-like, some with foamy cytoplasm, and scattered large multinucleated cells with bizarre nuclei. For the most part, the tumor had a distinct border to the surrounding brain parenchyma, except for a single zone of invasion. As per the depicted morphology, with a lack of pathognomic features of GCGBM, the diagnosis of PXA was defined, and the oncologic committee reevaluated the patient with treatment reinitiation. Based on the close morphological profile of these neoplasias, it is likely that in the case of limited material, multiple PXA cases are diagnosed as GCGBM, resulting in misdiagnosed long survivors.