ABSTRACT
Sixty eight cases of soft tissue sarcoma [STS] selected from the files of Pathology Departments, Benha Faculty of Medicine-Zagazig University and National Cairo Institute- Cairo University, during the period from 1993 to 1997, were examined by light microscopy and class Wed into 44 differentiated cases [64.7%] and 24 undifferentiated cases [35.3%]. The differentiated cases were studied by histochemical and immunohistochemical stains using a panel of Antibodies. We applied the results of histological, histochemical and immunohistochemical reactivity of classified cases -on the 24 undifferentiated cases in trial to classify them. Histochemical and immunohistochemical stains were of most value in classification of 18 [75%] out of 24 undifferentiated cases as: 4 cases liposarcoma, 4 malignant fibrous histiocytoma [MFH], 4 leiomyosarcoma, 2 angiosarcoma, one case of monophasic synovial sarcoma and 3 cases of rhabdomyosarcoma. Combination of electron microscopic [E.M.] with light microscopic examination, [L.M], histochemical and immunohistochemical stains resulted in a specific diagnosis in 4 out of 6 unclassified cases [66.7%], This work supports the view that L.M. readily discriminate between differentiated tumor types. Special histochemical stains could be supportive and confirmation. Immunohistochemical markers together with appropriate clinical and histological features can minimize the number of undifferentiated sarcomas. In problematic cases, immunohistochemical and E.M. have complementary role