OCT4 immunohistochemistry after staging laparoscopic retroperitoneal lymphadenectomy for testicular tumor.

Twenty to thirty percent of patients with clinical stage I testicular tumor have metastases in the retroperitoneum. The aim of this study was to evaluate the role of OCT4 immunohistochemistry in histopathologic diagnosis of lymph node metastases in patients with nonseminomatous germ cell testicular tumors. All clinical stage I patients with staging laparoscopic retroperitoneal lymphadenectomy from 2001 until 2009 were included. Archived materials of dissected lymph nodes were reassessed and additional immunohistochemical staining with OCT4 antibody was performed in patients diagnosed as free from metastases. Each slide was visually estimated for the percentage of tumor cells showing nuclear immunoreactivity for OCT4. The study included 93 patients, of which 30 (32.3%) had initially positive retroperitoneal lymph nodes. Of the remaining 63 patients, materials were missing for 5 patients, so additional immunohistochemical staining was performed in 58 patients. Of these, two (3.4%) patients were OCT4 positive, suggesting a conclusion that they were initially misdiagnosed as stage I and metastasis free. OCT4 proved its value in detecting retroperitoneal metastases. Staging laparoscopic retroperitoneal lymphadenectomy for nonseminomatous germ cell testicular tumors in clinical stage I is a reasonable option for selected patients.