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Washington University Experience | NEOPLASMS - CRANIAL AND PARASPINAL NERVEs | Malignant Peripheral Nerve Sheath Tumor (MPNST) | 8E MPNST (Case 8) GFAP 2.jpg
Scattered stained individual cells are immunoreactive for GFAP. ---- Not Shown: Neurofilament protein and epithelial membrane antigen (EMA) are negative. Reactivity for p53 (nuclear pattern) is moderate to strong within the vast majority of the tumor cells. Reactivity for synaptophysin (cytoplasmic pattern) is weak and highlights only rare tumor cells. No reactivity is observed for Melan-A. ---- Comment: These histomorphologic and immunophenotypic features are diagnostic of high grade malignant peripheral nerve sheath tumor (MPNST). Based on the French Federation of Cancer Centers Sarcoma Group's grading system (FNCLCC) warrant a grade 3 diagnosis (total score of 6: 3 for tumor differentiation [undifferentiated on H&E-stained sections], 3 for mitotic index, and 0 for necrosis [no necrosis]. By WHO grading criteria, the material available for review warrants WHO grade III (detection of necrosis would warrant WHO grade IV). For these reasons, we appended "high grade" to the diagnosis of MPNST.
