OCT4 is superior to CD30 in the diagnosis of metastatic embryonal carcinomas after chemotherapy.

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.