The Primary germ cell tumor (GCT) is a relatively rare tumor usually located in the anterior mediastinum. A previous study has postulated that OCT4 is a nuclear transcription factor that is expressed in pluripotent embryonic germ cells. This study attempted to identify and characterize OCT4 expression in the GCTs originating in the mediastinum.
A retrospective study conducted between 1983 and 2005 included 46 consecutive patients with GCTs in the mediastinum whose tumors had been surgically excised. We examined histological sections from 46 primary GCTs in the mediastinum, including teratoma (n=27; 58.7%), seminoma (n=10; 21.7%), yolk sac tumor (n=6; 13%), embryonal carcinoma (n=1; 2.1%), and mixed GCTs (n=2; 4%; one consisted of teratoma and yolk sac tumor, and the other teratoma, yolk sac tumor and seminoma). Each tumor was examined with hematoxylin and eosin staining and with anti-OCT4 antibodies. An overexpression of OCT4 was studied using immunohistochemistry.
The patient population was comprised of 16 (34.8%) women and 30 (65.2%) men. The mean age of patient participants was 25.1 years, with an age range of 9 to 56 years. The presentations included: asymptomatic tumor (28.5%), dyspnea (17.1%), coughing (22.8%), superior vena syndrome (5.7%), chest pain (20%), and fever (5.7%). The therapies administered were surgical excision (75%), followed by chemotherapy (48.6%) and/or radiotherapy (31.4%). Serum tumor markers were measured for twenty (47%) of the 46 patients whose, including 68% elevated alpha-fetoprotein, 30% elevated beta subunits of human chorionic gonadotropin, and 17% elevated carcinoembryonic antigen. There was greater than 90% nuclear staining of the embryonal carcinoma and seminoma tumor cells with little to no background staining. The other GCT components (yolk sac tumor and teratoma) showed no staining.
We conclude that immunostaining with anti-OCT4 antibodies is a useful diagnostic tool in the identification of primary embryonal carcinomas and seminomas in the GCT originating in the mediastinum.
anti-OCT4 antibodies is a useful diagnostic tool in the identification of mediastinal primary embryonal carcinomas and seminomas.
Pao-Hsien Chu, None.