Abstract

To determine the therapeutic plan and to predict the prognosis, it is a pivotal and important task to differentiate the exact nature of the various undifferentiated neoplasms. In order to solve this problem, the electron microscopy has once been considered only method in certain cases. Recently, however, the immunoperoxidase staining method which is less expensive and easier to usethan electron microscopy has been developed and introduced. To evaluate the diagnostic value of epithelial membrane antigen(EMA), carcinoembryonic antigen(CEA) and leukocyte common antigen(LCA) immunoperoxidase method, the authors applied these staining in 15 cases of which exact diagnoses were difficult with conventional routine and special stains, using the formalin-fixed and paraffin-embedded tissue sections. The results are as follows: 1) EMA was helpful in confirming the diagnosis or revising to the proper diagnosis of undifferentiated carcinoma in 4 of 6 cases and in excluding the possibility of hepatocellular carcinoma and melanoma in 2 cases, respectively. The negative stainabilities in one case of choriocarcinoma and one case of malignant fibrous histiocytoma was useful to exclude the possibility of squamous cell carcinoma and the positive stainability in one case of giant cell carcinoma to exclude the possibility of sarcoma. 2) The diagnostic value of CEA was similar to that of EMA; CEA was useful to differentiate from malignant lymphoma in one case of epithelial tumor in which CEA was positive and EMA negative. 3) LCA was useful to differentiate one case of malignant lymphoma from undifferentiated carcinoma and to confirm Ewing's sarcoma from malignant lymphoma in one case.