Lipidized meningothelial tumor cells in "xanthomatous" meningioma express macrophage antigen.

A case of "xanthomatous" meningioma was examined by light and electron microscopy as well as immunohistology. Lipid-laden "xanthomatous" cells were shown to be meningothelial by all ultrastructural criteria. All tumor cells (lipidized and non-lipidized) expressed vimentin in their cytoplasm, but only the lipidized cells showed the presence of the macrophage marker HAM-56. This finding suggests that, as in some other areas of general pathology, immunological markers may serve as indicators of a specific activity (in this case phagocytosis), rather than merely histogenesis.