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.
The term angiomatous is applied to the subgroup of meningiomas, in which numerous vessels prevail on the background of an otherwise typical meningioma.7 Such extremely vascularized meningiomas are rarely encountered. It is a generally held belief that the term angiomatous is more a descriptor than a diagnosis and has no prognostic or any other clinical significance.1 Furthermore, it has been argued that the presence of this somewhat indistinctively defined variant might be only justified to represent a niche for highly vascularized meningiomas to distinguish them from both hemangiopericytoma and hemangioblastoma.13 However, the clinicopathologic characteristics of angiomatous meningioma have not been systematically analyzed in a large series so far. Interpretation of some older studies is also hampered by the fact that the term “angioblastic” meningioma has been used to group hemangiopericytomas, hemangioblastomas, as well as highly vascularized meningiomas following the classification of Cushing and Eisenhardt.2 We therefore aimed to characterize histopathologic and clinical features of angiomatous meningiomas.