Germ cell tumor pathophysiology

• Germ cells are the cells that develop in the embryo and become they make up the reproductive system in males and females.
• After the development of germ cells, they follow the body midline path and descend into the pelvis as ovarian cells or into the scrotal sac as testicular cells.
• Th ovaries and testes are called gonads and many ovarian and testicular tumors have germ cell origin.
• The pathophysiology of germ cell tumors is different based on the classification of germ cell tumors
• Each of the distinct entities of germ cell tumor has a different pathogenesis
• Germ cell tumors are classified as;
  • Gonadal
    • Seminoma
    • Dysgerminoma
    • Germinoma
  • Extragonadal
    • Embryonic
      • Mature/Immature teratoma
    • Extraembryonic
      • Chorio carcinoma/Yolk sac tumor
        

Testicular Seminoma

• Accounts for about a third of all testicular germ cell malignancies and is one of the most treatable cancers with a survival rate of 98% to 99% in early-stage disease
• originates in the germinal epithelium of the seminiferous tubules as a result from the proliferation of immature spermatogonia   
• On gross pathology, seminoma is characterized by pale gray to yellow nodules that are uniform or slightly lobulated and often bulge from the cut surface.
• Microscopic Pathology:
  • On microscopic pathology, seminoma is characterized by

  • Cells with fried egg appearance - key feature

  • Clear cytoplasm
  • Central nucleus, with prominent nucleolus. Nucleus may have "corners", i.e. it is not round.

  • Lymphocytes - interspersed (common)
  • Syncytiotrophoblasts, present in 10-20% of seminoma

  • Large, irregular, vesicular nuclei
  • Eosinophilic vacuolated cytoplasm (contains hCG)

  • Florid granulomatous reaction

  • Approximately 24% of Stage I seminomas have lymphovascular invasion for stage I (Tx, N0, M0).
  • Intertubular seminoma may not form a discrete mass and mimic a benign testis.