SECRETORY MENINGIOMA - CLINICAL, HISTOLOGIC, AND IMMUNOHISTOCHEMICAL FINDINGS IN 31 CASES

BACKGROUND. Secretory meningioma is a rare histologic variant characte rized by a unique epithelial differentiation of meningothelial cells r esulting in the production of hyaline inclusions. Most previous report s have presented single case observations. The authors selected 31 cas es for a clinicopathologic study to characterize this type of tumor fu rther. METHODS. Clinical data were compiled and the extent of peritumo ral edema was assessed from preoperative computed tomography or magnet ic resonance imaging scans. Preparations of surgical specimens of all tumors were studied after both conventional histologic and immunohisto chemical preparations were made. Immunostaining was performed by eithe r the avidin-biotin complex method or the alkaline phosphatase-antialk aline phosphatase method using 22 primary antibodies. RESULTS. In the tumor collection used in this study, secretory meningiomas represented 3% of meningiomas. The female-to-male ratio was 9:1. Most tumors were located at the sphenoid ridge or at the frontal convexity, and recurr ences were not observed. Eighty-four percent of tumors presented with slight to marked peritumoral edema. The MIB-1 staining index showed a mean of 3.8%. Inclusions and surrounding cells consistently expressed epithelial membrane antigen, cytokeratins, carcinoembryonic antigen, a nd carbohydrate antigen 19-9. In decreasing frequency, they also conta ined alpha(1)-antitrypsin, immunoglobulin (Ig)A, alpha(1)-antichymotry psin, IgM, and IgG. Cells positive for vimentin and S-100 did not cont ain inclusions. All tumors were positive for progesterone receptors. M acrophages were stained with antibodies to factor XIIIa, human leukocy te antigen-DR, and alpha(1)-antitrypsin. In 64% of cases, tumor vessel s lacked expression of glucose transporter protein 1. CONCLUSIONS. The classification of secretory meningioma as a distinct variant has been justified on clinical, histologic, and immunohistochemical grounds. T he unique epithelial features call attention to the broad spectrum of differentiation properties found in meningiomas. (C) 1997 American Can cer Society.