Atypical meningioma: a retrospective analysis of six cases and literature review

BACKGROUND: Atypical meningiomas (AM) are WHO grade II tumors with high heterogeneity and invasiveness, which are unique in their clinical presentation, imaging, pathology, treatment, and prognosis. In 2016, the diagnosis of AM remodified by the classification of central nervous system tumors of World Health Organization (WHO). In order to further analyze the diagnosis and treatment characteristics of AM, the clinical diagnosis, surgery treatment and follow-up data of 6 patients with AM in our hospital from January 2016 to December 2019 were analyzed retrospectively. METHODS: The clinical diagnosis, treatment and follow-up data of six patients with AM admitted to our hospital between January 2016 and December 2019 were analyzed retrospectively, and related literature was reviewed. RESULTS: The main clinical symptoms of the patients were increased intracranial pressure and functional area symptoms. MRI showed obvious enhancement, an unclear boundary with adjacent brain tissue, a large edema signal shadow in the white matter of peripheral brain tissue, and rapid enlargement in some cases. Pathological manifestations showed local necrosis and increased nuclear division activity. The results of immunocytochemistry showed that vimentin and epithelial membrane antigen (EMA) were positive, S-100 protein (S-100) and glial fibrillary acidic protein (GFAP) were negative, and the Ki-67 proliferation index was increased. Simpson’s grade I-II resection was performed in five cases and no recurrence found after 4 to 46 months of follow-up. Simpson’s grade IV resection was performed in one case and no follow-up was performed after discharge. CONCLUSIONS: AMs are highly heterogeneous and invasive. Histologic diagnosis is the gold standard for diagnosis and surgical resection is the first treatment choice. Total resection (Simpson I-II) helps to reduce recurrence.