Germ cell tumor pathophysiology

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Dysgerminoma


Testicular Seminoma

Germinoma

  • On microscopic histopathological analysis, uniform cells that resemble primordial germ cells, consisting of large, round cells with vesicular nuclei and clear or finely granular cytoplasm that is eosinophilic are characteristic findings of germinoma.
  • Pure germinomas are composed of large polygonal undifferentiated cells with abundant cytoplasm arranged in nests separated by bands of connective tissue
  • The histologic appearance of NGGCTs varies depending upon the specific cell types present[2]
  • Infiltrating small lymphocytes are often present and can obscure the diagnosis, especially in small biopsy specimens[2]
  • Genes involved in the pathogenesis of germinoma include gains of 1p, 8p, and 12q and losses of 13q and 18q, duplication of the short arm of chromosome 12, loss of 1p and 6q, alterations in sex chromosomes in children, alterations of the p14 gene, mutations of the c-kit gene, aberrations of CCND2 (12P13), and RB1, and gain-of-function mutations of KIT.
  • The progression to germinoma usually involves the mutations of the KIT/RAS signalling or AKT1/mtor pathways and cyclin/CDK-RB-E2F pathway if CCND2(12P13) and RB1 genes are aberrated

Yolk sac tumors

  • The hypermethylation of the RUNX3 gene promoter and overexpression of GATA-4, a transcription factor has been associated with the development of endodermal sinus tumor.
  • On gross pathology, solid gray-white with a gelatinous, myxoid, or mucoid appearance, necrosis, cystic changes, and hemorrhage are characteristic findings of endodermal sinus tumor.
  • On microscopic histopathological analysis, Schiller-Duval bodies is a characteristic finding of endodermal sinus tumor.

Teratomas

Pineal teratoma:

  • Mature teratomas are benign, mature, well-differentiated cystic lesions; whereas immature teratomas are poorly differentiated lesions with solid components and malignant transformation
  • On other occasions, mature teratomas contain elements that undergo malignant transformation (most commonly squamous components).
  • Fat
  • Cystic spaces due to mucus production or other exocrine products
  • Soft-tissue from any part of the body Calcification, including teeth
  • On microscopic histopathological analysis, pineal teratoma is characterized by cells originating from at least two and usually all three embryonic layers (ectoderm, mesoderm, and endoderm).
  • The histological subtype may not necessarily determine the biological behavior

Sacrococcygeal teratoma

Microscopic Pathology of sacrococcygeal teratoma can be divided into following two types depending on the microscopic pathology:

Mature Teratoma

Immature Teratoma



Polyembryoma

  • Polyembryoma is a rare, very aggressive, and usually found in the ovaries
  • It has features of both yolk sac tumor and undifferentiated teratoma/embryonal carcinoma
  • A characteristic finding of embryoid bodies lying in a loose mesenchymal stroma can be found
  • It can be seen in association with Klinefelter syndrome [3]

Gonadoblastoma

  • Gonadoblastoma is a benign tumor that almost exclusively involves individuals suspected of intersex disorders. This tumor comprised of underdeveloped germ cells and sex-cord stromal cells which defines the term gonadoblastoma.
  • The exact pathogenesis of gonadoblastoma is not fully understood. Gonadal development starts at 5 weeks of gestation and continues according to sex chromosomes. Any defects in this complicated process lead to defective gonadal development and gonadal dysgenesis and subsequently, it may be converted to gonadoblastoma in 20% to 30% of the cases.

References

  1. 1.0 1.1
  2. 2.0 2.1
  3. Beresford L, Fernandez CV, Cummings E, Sanderson S, Ming-Yu W, Giacomantonio M (2003). "Mediastinal polyembryoma associated with Klinefelter syndrome". J Pediatr Hematol Oncol. 25 (4): 321–3. PMID 12679648.