Testis & paratestis
Germ cell tumors
Polyembryoma
Author: Andres Matoso, M.D.
Last author update: 1 September 2017
Last staff update: 12 August 2024
Copyright: 2002-2025, PathologyOutlines.com, Inc.
PubMed Search: Testis polyembryoma
Table of Contents
Definition / 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 #1Cite this page: Matoso A. Polyembryoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/testispolyembryoma.html. Accessed January 14th, 2025.
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
Essential features
- Central core of embryonal carcinoma cells, amnion-like cavity and yolk sac tumor component that accounts for approximately 90% of tumor
Epidemiology
- Extremely rare, same age as germ cell tumors
Clinical features
- Same as germ cell tumors
- Elevation of serum AFP and beta HCG
Prognostic factors
- Same as mixed germ cell tumors
Treatment
- Same as mixed germ cell tumor with teratoma
Gross images
Contributed by Delia Perez-Montiel, M.D.
40 year old man
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
Microscopic (histologic) images
Contributed by Delia Perez-Montiel, M.D.
Positive stains
- OCT3 / 4, CD30 and keratin (embryonal carcinoma component)
- Glypican 3, AFP and keratin (yolk sac component)
Additional references
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.
Board review style answer #1
D. Proportion of embrioid bodies in polyembryomas is 90% or
higher of the entire tumor.
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Reference: Polyembryoma
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Reference: Polyembryoma
