Seminoma Arises from Germ Cells
Seminoma arises from germ cells, specifically from cells analogous to primordial germ cells/gonocytes present during early embryonic development. 1
Cellular Origin and Pathogenesis
More than 95% of malignant testicular tumors, including seminoma, arise from germ cells. 1
Histopathologically, seminomas are characterized by cells that resemble primordial germ cells/gonocytes from early embryonic development, distinguishing them from non-seminomas which show differentiation patterns from embryonic and extra-embryonic tissues. 1
The major pre-neoplastic lesion for most adult germ cell tumors (GCTs), including seminoma, is germ-cell neoplasia in situ (GCNIS), which represents the common precursor to invasive disease. 1
Developmental Context
Testicular germ cell tumors in postpubertal men (the typical age group for seminoma) are thought to develop from the failure of normal maturation of gonocytes during fetal or postnatal development, with progression to invasive tumors occurring after puberty. 2
Intratubular germ cell neoplasia of the unclassified type represents the common precursor to the great majority of testicular germ cell tumors, and seminoma appears to represent the invasive derivative of this precursor lesion. 3
Important Distinction
- Spermatocytic seminoma (now called spermatocytic tumor) is a distinct entity that does NOT arise from GCNIS and has a different cell of origin than classical seminoma. 1, 4 This rare variant occurs in older patients and has different biological characteristics, including absence of the typical chromosome 12p abnormalities seen in classical seminoma. 5, 4