[The ultrastructural and immunohistochemical observations of anaplastic meningioma].

Eighteen cases of anaplastic meningioma were studied by LM, EM and immunohistochemistry for vimentin, EMA, keratin, GFAP and S-100. Microscopically, there were four histologic types, i.e. fibrosarcoma-like, angiosarcoma-like, polymorphic giant cell sarcoma-like and angiopapillary structure. By EM, four kinds of cells: undifferentiated cell, intermediate transitional cell, spindle-shaped cell, and giant cell, were found and variant transitions from undifferentiated or poorly, differentiated to meningioma cells were observed. Their ultrastructures and immunohistochemical features are similar to those of malignant mesothelioma. Since these two kinds of neoplasm showed both mesenchymal and epithelial cells in the features, the authors consider that their histogenesis may also be similar.