Epidermal growth factor receptor is a marker for syncytiotrophoblastic cells in testicular germ cell tumors

The epidermal growth factor receptor (EGFR) has been implicated in the pathogenesis, therapy and prognosis of various tumor types. The aim of this study was to investigate EGFR expression in a large series of testicular germ cell tumors (TGCTs). A total of 88 TGCTs (37 of pure type and 51 of mixed type) comprising a total of 44 seminoma, 49 embryonal carcinoma, 32 yolk sac tumor, 28 teratoma and 7 choriocarcinoma components were immunostained for EGFR. EGFR reactivity was observed in the stromal cells of embryonal carcinoma (29%) and in epithelial compartments of teratoma (71%). In addition, EGFR staining was consistently detected in syncytiotrophoblastic cells of choriocarcinoma, seminoma, embryonal carcinoma and yolk sac tumor components. EGFR staining, similar to beta-human chorionic gonadotropin (HCG) immunohistochemistry, was efficiently able to identify syncytiotrophoblastic cells in TGCTs. This study shows that EGFR is expressed in a subset of testicular germ cell tumors and suggests that EGFR may be a useful marker for syncytiotrophoblastic cells.