Epithelial-glial transition in an atypical meningioma - a case report

Atypical meningiomas with a mixed glial-epithelial phenotype are rare reports, and here we described an aggressive case on which double immunofluorescence ascertained the co-expression of epithelial membrane antigen (EMA) with glial fibrillary acidic protein (GFAP) in the same tumor cells. A 62-year-old female presented with acute intracranial hypertension symptoms occurred over the last 24 hours, muscle weakness on the right side, cerebellar dysarthria, and wide base gate. Magnetic resonance imaging (MRI) examination showed a right cerebellar hemisphere non-homogenous tumor, with intense gadophylia, diffuse contours, and necrotic inner areas. There were also scar-like areas at the level of the left cerebellar hemisphere, and the patient recalled a previous surgical intervention at the age of 6 years old without further diagnostic data. The patient suffered an ischemic event in the brain stem and died shortly after the surgical removal of the tumor. Histopathology revealed an epithelial-like tumor with moderately pleomorphic and elongated cells arranged in fascicles, rare necrotic areas, and a few proliferating multilayered vessels structures. Immunohistochemistry (IHC) revealed variable EMA positivity, intense vimentin staining, rare GFAP-positive intra-tumor areas, a moderate expression for cytokeratin 8/18, reduced labeling for an anti-progesterone receptor (PrgR) antibody, cluster of differentiation (CD) 10 negativity, and a high Ki-67 proliferating index of around 40%. The case was deemed as an atypical meningioma, and interestingly, a double IHC for GFAP∕EMA revealed a strong colocalization of the two markers in the tumor mass. Although extremely rare, the reports of meningiomas expressing a mixed epithelial∕glial profile might be connected with their aggressive evolution. Double IHC might help in predicting the evolution of these cases and determine which patients should benefit from closer surveillance.