Correctly diagnosing a metastatic
germ cell tumor after
chemotherapy may be challenging because of the diverse morphological manifestations of postchemotherapy
tumors. Both OCT4 and CD30 are sensitive markers for the identification of primary
embryonal carcinomas; however, loss of expression of CD30 (65%) has been reported in metastatic
embryonal carcinomas after
chemotherapy. The present study was conducted to evaluate the expression patterns of OCT4 and CD30 in postchemotherapy metastatic
embryonal carcinomas and to compare their utility as diagnostic tools. Twenty-five cases of metastatic
embryonal carcinoma after
chemotherapy were immunohistochemically analyzed for CD30, OCT4, and
cytokeratin AE1/AE3 expression. The staining intensities and the percentages of positively staining
tumor cells were recorded. Nineteen (76%) of 25 cases revealed diffuse, moderate to strong nuclear OCT4 staining in postchemotherapy
embryonal carcinomas. Among these 19 OCT4-positive cases, 8 also revealed diffuse and moderate to strong membranous CD30 staining. Seven of these OCT4-positive cases retained focal and weak CD30 expression. The remaining 4 OCT4-positive cases demonstrated a complete loss of CD30 expression. The 19 OCT4-positive cases showed a positive but variable
cytokeratin AE1/AE3 expression pattern. Six (24%) of 25 cases were negative for both CD30 and OCT4 but demonstrated diffuse and strong
cytokeratin AE1/AE3 staining. OCT4 is a useful diagnostic marker to identify metastatic
embryonal carcinomas after
chemotherapy, with a better sensitivity than CD30.