Concomitant germ cell tumors in monozygotic twins

Simultaneously occurring embryonal cell tumors in a 38-year-old set of monozygotic twin brothers are reported. This is the eighth documented case of testicular cancer in twins and it is unique since it is the first report to describe bilateral testicular tumors in 1 of the twin brothers. The role of genetics in the development of certain cancers warrants further study. This documentation of testicular tumors in serologically proved identical twins is used as a basis for discussion of the role of heredity as a possible significant factor in germ cell tumor pathogenesis.