AIF1 and meningioma: Histopathologically, the dura mater and subarachnoid space were infiltrated by sheets of CD79a-positive large neoplastic round cells, accompanied by numerous non-neoplastic CD3-positive T cells and IBA1-positive histiocytes, consistent with a T-cell-rich large B-cell lymphoma, and whorls of spindle-shaped cells, consistent with a meningioma.