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Washington University Experience | NEOPLASMS (MENINGIOMA) | Anaplastic | 23F Ancillary Data & Denouement
23F Ancillary data & Denouement: A wide panel of immunohistochemical stains was performed for the better characterization of the tumor. These demonstrate the tumor cells to show strong and diffuse positivity for vimentin (cytoplasmic) along-with bcl2 (cytoplasmic) expression in a large subset. In addition, there is focal expression of CD99 (cytoplasmic), and rare positivity of CAM5.2 (cytoplasmic) by the tumor. A GFAP demonstrates its infiltration into the adjacent brain parenchyma but it is negative in the neoplastic cells. Additional immunohistochemical stains including several epithelial markers (pancytokeratin, CK7, CK20, CK5/6), more specific markers like CDX2, TTF1 and thrombomodulin, neuroendocrine markers (chromogranin, synaptophysin), mesenchymal markers (CD34, SMA) and melanocytic marker (HMB-45) are all negative. In addition, fluorescence in situ hybridization studies were performed, and these show 1p36 deletion without loss of 22q or 14q often seen in high grade meningioma. ---- Comment: The collective findings are those of a poorly differentiated malignant neoplasm. Based on its extensive workup (as well as its focal dural attachment on imaging), our considerations included anaplastic meningioma and anaplastic hemangiopericytoma. While its focal papillary architecture as well as rare PR expression and loss of chromosome 1p36 favored the former, its expression of bcl2 and CD99 argued for the latter diagnosis. We additionally performed a STAT6 immunostain since its nuclear expression is associated with hemangiopericytoma (with 100% frequency) in the recent literature; this particular tumor lacks nuclear expression of STAT6 protein and shows its immunoreactivity limited to only cytoplasm, we favor the overall findings to be most consistent with an anaplastic meningioma.
