A Rare Case of Xanthomatous Meningioma.

Xanthomatous meningioma is an extremely rare subtype of metaplastic meningiomas with few cases reported in the literature. Histopathologically, it is composed of oval-shaped cells that have central nuclei and cytoplasm with lipid-filled vacuoles, resembling macrophages. Here, the authors present a case of xanthomatous meningioma and discuss the hypotheses related to its origin and the differential diagnosis. A 40-year-old woman presented with an increased headache complaint over the past month. A computed tomography scan revealed a heterogeneous mass on the right parietal lobe, following which a right craniotomy was done. Microscopic examination showed neoplastic meningothelial cells with whorl formation and areas of xanthomatous changes. Both meningothelial and xanthomatous cells were positive with vimentin, progesterone, and epithelial membrane antigen. CD68 and lysozyme were expressed only in the xanthomatous component, and there was no expression with periodic acid-Schiff (PAS) stain and PAS-diastase. As the diagnostic criteria of atypical meningioma were not observed, a diagnosis of xanthomatous meningioma, WHO grade I, was made. Owing to the characteristic xanthomatous changes, its differential diagnosis includes grade II clear cell meningioma, Rosai-Dorfman disease, and hemangioblastoma. To avoid misidentifying these cells as macrophages, a high degree of awareness of this unique subtype of meningioma is required.