Angiomatous meningioma: a clinicopathologic study of 38 cases.

To characterize histopathological and clinical features of angiomatous meningioma, 38 cases of angiomatous meningioma, ie, meningiomas whose vascular component exceeded 50% of the total tumor area, are reported. In addition to histologic examinations, clinical characteristics as well as follow-up data were compiled. Angiomatous meningiomas constituted 2.1% of all meningiomas. Histologic signs of atypia or anaplasia were not observed in any tumor. The mean MIB-1/Ki67 proliferation index was 2.4%. Based on vessel size, two distinct histologic subtypes were identified, which differed in localization but not with regards to sex, age, presence of peritumoral edema, MIB-1/Ki67 proliferation index, or progesterone receptor status. In patients with gross tumor resection, no recurrences occurred. To conclude, angiomatous meningiomas share histologic and clinical features of benign meningiomas. Since all angiomatous meningiomas examined here were grade 1 tumors, the diagnosis of angiomatous meningioma may have prognostic implications. Therefore, the existence of this rare subgroup of meningioma appears justified.