Testis & epididymis
Germ cell tumors
Epithelioid trophoblastic tumor


Topic Completed: 1 April 2018

Minor changes: 9 September 2020

Copyright: 2019-2020, PathologyOutlines.com, Inc.

PubMed Search: Epithelioid trophoblastic tumor [title]


Vikas Mehta M.D.
Page views in 2019: 549
Page views in 2020 to date: 487
Cite this page: Mehta, V. Epithelioid trophoblastic tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/testisepithelioidtrophoblastictumor.html. Accessed September 20th, 2020.
Definition / general
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
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

Positive stains
Negative stains
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
Board review style question #1
Epithelial trophoblastic tumor can be differentiated from a choriocarcinoma by all the following except:

  1. Biphasic pattern of syncytiotrophoblastic and mononucleated trophoblast cells
  2. HSD3B1 Positivity
  3. Ki67 index of 10 - 25%
  4. Prominent fibrinoid material around vessels
Board review answer #1
A. Biphasic pattern of syncytiotrophoblastic and mononucleated trophoblast cells

Reference: Testis and epididymis - Epithelioid trophoblastic tumor

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