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Washington University Experience | NEOPLASMS (GLIAL) | Astroblastoma | 4F2 Astroblastoma, focal anaplasia (Case 4) VIM 3.jpg
Vimentin is strongly and diffusely positive. ---- Other Immunohistochemistry (Not shown): Neurofilament stains residual axons predominantly at the periphery of the neoplasm, thus highlighting the pushing borders of the tumor. Focally, superficial infiltration of adjacent parenchyma is evident. Neoplastic cells are negative for cytokeratin, smooth muscle actin, and synaptophysin. Ultrastructural studies performed at an OSH show abundant intracytoplasmic collections of intermediate filaments with occasional cell processes and, focally, demonstrate cilia and intercellular junctions, reminiscent of ependymal differentiation. ---- Comment: The morphologic, immunohistochemical, and ultrastructural features support the diagnosis of astroblastoma with focal high-grade features. Although the majority of the neoplasm has a low-grade appearance, the finding of focal hypercellular regions with increased pleomorphism, mitotic activity, and lack of perivascular hyalinization suggests a higher grade element. Given the rarity of this diagnosis, firm grading criteria have not been established and the clinical behavior is not always predictable
