Testis and epididymis
Germ cell tumors
Epithelial trophoblastic tumor



Topic Completed: 1 April 2018

Revised: 29 July 2019

Copyright: 2019, PathologyOutlines.com, Inc.

PubMed Search: Epithelioid trophoblastic tumor [title]


Vikas Mehta M.D.
Page views in 2018: 188
Page views in 2019 to date: 328
Cite this page: Mehta, V. Epithelioid trophoblastic tumor. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/testisepithelioidtrophoblastictumor.html. Accessed August 25th, 2019.
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 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 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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