Testis & paratestis
Germ cell tumors
Epithelioid trophoblastic tumor
Author: Vikas Mehta, M.D.
Last author update: 1 April 2018
Last staff update: 6 February 2024 (update in progress)
Copyright: 2019-2024, PathologyOutlines.com, Inc.
PubMed Search: Epithelioid trophoblastic tumor [title]
Table of Contents
Definition / general | Essential features | Terminology | Epidemiology | Sites | Etiology | Clinical features | Diagnosis | Laboratory | Radiology description | Prognostic factors | Case reports | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Differential diagnosis | Additional references | Board review style question #1 | Board review style answer #1Cite this page: Mehta, V. Epithelioid trophoblastic tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/testisepithelioidtrophoblastictumor.html. Accessed April 23rd, 2024.
Definition / general
- Tumors of trophoblastic derivation in testis show morphologic spectrum analogous to the trophoblastic tumors of the female genital tract including choriocarcinoma, epithelioid trophoblastic tumor (ETT) and placental site trophoblastic tumor (PSTT)
- Other than choriocarcinoma, these tumors are very rare in the testis but have been reported on occasion in association with other germ cell tumors
Essential features
- Unusual trophoblastic tumor, distinct from choriocarcinoma and placental site trophoblastic tumor (PSTT) with morphologic features similar to a carcinoma
- Both morphologic and immunohistochemical studies showed that the ETT is mainly composed of chorionic type intermediate trophoblastic cells
Terminology
- Atypical choriocarcinoma
Epidemiology
- Rare gestational trophoblastic neoplasm with only 52 cases documented in literature
- Typically occurs in young men between 19 and 43 years
Sites
- Testis, metastasis to lymph nodes, lung
Etiology
- Seems to develop from neoplastic transformation of cytotrophoblastic cells that assume a differentiation toward the chorionic type intermediate trophoblastic cells that are normally found in chorion laeve (fetal membrane)
Clinical features
- Typically seen in young men between 19 and 43 years
- Serum βhCG may show mildly increased levels
Diagnosis
- Based on characteristic morphology and immunoprofile
Laboratory
- May be associated with mild elevation of βhCG
Radiology description
- No characteristic features
Prognostic factors
- Not an aggressive tumor
- Requires no additional treatment after initial treatment for germ cell tumor
Case reports
- 39 year old man with metastatic epithelioid trophoblastic tumor (Am J Surg Pathol 2009;33:1902)
Microscopic (histologic) description
- Can assume several growth patterns including cohesive nests of squamoid cells with abundant pink cytoplasm and lacking associated hemorrhage
- Tumor cells have single pleomorphic and hyperchromatic nuclei with prominent nucleoli and occasional multinucleation along with well defined cytoplasmic membranes without discernible intercellular bridges
- Intracytoplasmic vacuoles containing fibrinoid cellular debris, sometimes with pyknotic nuclear fragments can be identified
- Extracellular hyaline material and lymphocytes at periphery Infiltrating tumor nests and single squamoid cells can also be recognized
- Mitotic count ranges from few to several in different fields
- Occasional central cystic degeneration containing fibrinoid material is noted
- Most striking histologic feature is absent biphasic pattern of cytotrophoblasts and syncytiotrophoblasts
Microscopic (histologic) images
Contributed by Debra L. Zynger, M.D.
Testicular epithelial trophoblastic tumor
Negative stains
- HPL, SALL4, GPC3, OCT4, Melcam (CD146)
Differential diagnosis
- Choriocarcinoma: shows a biphasic pattern of syncytiotrophoblastic and mononucleated trophoblast cells and significant fresh hemorrhage, often with extensive necrosis; βhCG reactive syncytiotrophoblast cells which also usually shows only limited reactivity for HPL
- Regressing choriocarcinoma: large mononucleated trophoblast cells with pale to eosinophilic cytoplasm;
absent biphasic pattern of cytotrophoblasts and syncytiotrophoblasts with necrosis and fresh hemorrhage
hyalinized fibrous background with numerous hemosiderin laden macrophages
- Few mitotic figures
- Prominent Leydig cell hyperplasia in the surrounding testis
- AE1 / AE3 positive
- Placental site trophoblastic tumor: sheets of large discohesive cells with focal hemorrhage; HPL (focal), p63 positive
Additional references
Board review style question #1
Epithelial trophoblastic tumor can be differentiated from a choriocarcinoma by all the following except:
- Biphasic pattern of syncytiotrophoblastic and mononucleated trophoblast cells
- HSD3B1 Positivity
- Ki67 index of 10 - 25%
- Prominent fibrinoid material around vessels
Board review style answer #1
A. Biphasic pattern of syncytiotrophoblastic and mononucleated trophoblast cells
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Reference: Epithelioid trophoblastic tumor
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Reference: Epithelioid trophoblastic tumor
