Lesions of the rete testis in mice exposed prenatally to diethylstilbestrol.

Adenocarcinoma of the rete testis is an exceptionally rare and malignant testicular neoplasm. Although treatment of pregnant women with diethylstilbestrol (DES) results in reproductive tract abnormalities in their male offspring, increased incidence of testicular tumors has not been verified. However, recently three cases of seminoma have been described in men prenatally exposed to DES, suggesting an association of prenatal DES treatment and the subsequent development of testicular tumors. This report describes the treatment of outbred pregnant CD-1 mice with DES (100 micrograms/kg) on Days 9 through 16 of gestation and its effects on their male offspring. In addition to nonmalignant abnormalities such as retained testes which have been reported in men exposed prenatally to DES, lesions resembling adenocarcinoma of the rete testis were seen in prenatally DES-treated mice at 10 to 18 mo of age (11 of 233; 5%). No comparable lesions were seen in 96 age-matched control male mice. These results suggest an association of prenatal DES exposure and the subsequent development of testicular lesions in the rete testis of mice.