POSTIRRADIATED AND NONIRRADIATED GLIOSARCOMA - IMMUNOPHENOTYPICAL PROFILE

Background: Thirty-one gliosarcomas (25 nonirradiated and 6 postirradi ated tumors) were selected based on the presence of two distinctive ar eas: a malignant gliomatous and a sarcomatous component. In all cases, the sarcomatous component appears like fibrosarcoma or malignant fibr ous histiocytoma, Two tumors showed additional areas consisting of ost eochondroid differentiation, Methods: All tumors were examined using a ntibodies against Ulex europaeus agglutinin I (UEA), glial fibrillary acidic protein (GFAP), vimentin (VM), epithelial membrane antigen (EMA ), desmin, collagen IV, alpha-1 antitrypsin (alpha-1-AT) and smooth mu scle actin (SMA), Results: While the VM highlighted the sarcomatous ar eas of all tumors there were only scattered spindle cells that were GF AP-positive in the same areas, The alpha-1-AT was diffusely reactive i n the sarcomatous areas in 20 cases. Focal immunoreactivity was seen w ith SMA (20 tumors), UEA (8 tumors), EMA (5 tumors), collagen IV (5 tu mors) and desmin (4 tumors) in the nonvascular sarcomatous cells, Conc lusions: The range of immunophenotypical expression is likely to be a reflection of the capacity of a multipotential progenitor to undergo d ivergent differentiation. There is very little morphological differenc e between the postirradiated and nonirradiated tumors except that a hi gher proportion of postirradiated tumors are immunoreactive to SMA and desmin.