Table of ContentsDefinition / general | Essential features | Epidemiology | Clinical features | Prognostic factors | Treatment | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Additional references | Board review style question #1 | Board review style answer #1
Cite this page: Matoso A. Polyembryoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/testispolyembryoma.html. Accessed December 6th, 2022.
Definition / general
- Mixed germ cell tumor with predominant embryoid bodies (central core of embryonal carcinoma cells, amnion-like cavity and yolk sac tumor component)
- Elements other than the embryoid bodies, however, should constitute less than 10% of the tumor for the "polyembryoma" designation to be used (Mod Pathol 2005;18:S61)
- Resembles embryonic yolk sac
- Behaves like other mixed germ cell tumors
- Central core of embryonal carcinoma cells, amnion-like cavity and yolk sac tumor component that accounts for approximately 90% of tumor
- Extremely rare, same age as germ cell tumors
- Same as germ cell tumors
- Elevation of serum AFP and beta HCG
- Same as mixed germ cell tumors
- Same as mixed germ cell tumor with teratoma
Microscopic (histologic) description
- At low power, the stroma can give the tumor a lobular architecture
- Embryoid bodies are composed of a hyperchromatic disc of embryonal carcinoma
- Surrounding the disc of embryonal carcinoma is edematous stroma forming a cavity lined by yolk sac epithelium
Board review style question #1
What is the difference between a mixed germ cell tumor with embryoid bodies and a polyembryoma?
- Mixed germ cell tumors have components other than embryonal carcinoma and yolk sac tumor, while polyembryomas have only embryonal carcinoma and yolk sac tumor.
- Polyembryoma is not a germ cell tumor.
- Polyembryomas have many different types of embryoid bodies.
- Proportion of embryoid bodies in polyembryomas is 90% or higher of the entire tumor.