A case of metaplastic meningioma with extensive xanthomatous change.

We report a case of metaplastic meningioma with extensive xanthomatous change occurring in a 61-year-old woman. Magnetic resonance imaging demonstrated a well-demarcated, dura-based mass measuring 7 cm in maximal diameter in the right occipital to parietal area. Under a clinical diagnosis of meningioma, right parietal craniotomy was performed. Histologically, the tumor showed extensive xanthomatous change together with the common features of meningothelial meningioma. Tumor cells showed diffuse xanthomatous change in various quantities, and xanthomatous tumor cells frequently showed a gradual transition to the non-xanthomatous counterpart. The xanthomatous tumor cells showed immunopositivity for epithelial membrane antigen (EMA), vimentin, fatty acid synthase and several histiocytic markers (CD68, Ki-M1p, MAC387, lysozyme, alpha 1-antitrypsin and alpha 1-antichymotrypsin). In addition, there was patchy infiltration of foamy macrophages. Since these histiocytes did not show immunopositivity for EMA, these cells were distinguished from the xanthomatous tumor cells. These two types of xanthomatous changes comprised approximately two-thirds of the whole tumor tissue. Any atypical features such as necrosis, frequent mitotic figures or brain parenchymal invasion were not observed. We diagnosed this case as xanthomatous meningioma, WHO grade I.