Pathogenesis of testicular germ cell neoplasia: A conceptual approach

Testicular germ cell tumors are a diverse group of neoplasms, consisting of the prepubertal type 1 tumors, pure teratoma, and pure yolk sac tumor, the type 2 tumors, which are biologically malignant, preceded by germ cell neoplasia in situ, and harbor chromosome 12p abnormalities, and the type 3 tumor, spermatocytic tumor, which features chromosome 9p amplification.1 These arise in distinct clinical settings, and harbor distinct genetic abnormalities, immunohistochemical properties, and morphologic features. Here we have attempted to unify embryology, morphology, immunohistochemistry, and genetics in order to distill this fascinating group of neoplasms into what we hope is a useful framework for understanding their classification.