Background: The origin of testicular germ cell tumors (TGCTs) in children is poorly understood. There are clear differences between tumors in young children and those in adolescents and adults, which may suggest that they follow different pathways of tumorigenesis.
Methods: Tissue sections from 25 TGCTs (15 from patients age 4 years or younger and 10 from adolescents or adults) were stained immunohistochemically with anti-p53 (DO-1), CD34, and c-kit proto-oncogene protein product.
Results: CD34 expression was noted only in 5 prepubertal tumors. Expression of c-kit was observed in 9 of the 15 prepubertal tumors versus 2 of the 10 postpubertal cases. The intensity of expression was equal to that of the adjacent normal tubules in the prepubertal tumors, whereas the intensity was less in the postpubertal tumors. Expression of p53 was strong in 8 of the 10 tumors in adolescents or adults, with a 40-70% positivity, whereas only 6 of 15 prepubertal tumors expressed p53, with < 10% positivity.
Conclusions: CD34 expression in tumors in the group of young children suggests a possible link to teratomas and further provides insight into the fundamental differences between this group and the adolescent/adult group. The expression of c-kit and p53 provides further evidence that c-kit/SCF signaling and p53 play potentially different roles in the initiation and progression of these tumors. Future studies will be required to clarify this issue.