Pediatric Germ Cell Tumors: A Developmental Perspective

Figure 1

Germline development and histologic subtypes of GCTs. Primordial germ cells (PGCs) are specified early in embryogenesis and migrate through the embryo to the developing gonad. Type I GCTs exhibit a limited histologic spectrum, a partial erasure of genomic imprinting, and a propensity for development at extragonadal sites, all suggesting a derivation from early stages of germ cell development. Type II GCTs frequently contain foci of germ cell neoplasia in situ (GCNIS) and exhibit the full range of seminoma and nonseminoma histologies. Together with a more complete erasure of imprinting, these features suggest that the Type II tumors arise at a later stage of germline development.