Fig. 2

Histopathological changes of the lesion. The mass lesion showed scattered nests of meningothelial cells in a mixed inflammatory background with follicular center formation (A, HE*40). Nests of neoplastic meningothelial whorls were identified in lymphocytes and collagen (B, C, HE*100). Neoplastic cells were positive for EMA (D, *100) and PR (E, *100) in immunohistochemistry staining. Lymphocytes were composed of CD20 positive B cells (F, *100) and CD3 positive T cells (G, *100). Rare plasma cells were positive for IgG4 (H, *100). Fewer S100 positive cells existed (I, *100)