Ovary tumor
Endometrioid tumors
Endometrioid carcinoma

Authors: Shahrzad Ehdaivand, M.D. (see Authors page)

Revised: 20 May 2016, last major update December 2012

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed search: Ovarian endometrioid carcinoma

Related topics: Granulosa cell tumor like variant, Sertoliform variant, Spindle cell variant
Definition / General
  • 10-25% of primary ovarian carcinomas
  • 15% coexist with endometriosis; tumors may arise from endometriotic cysts
  • 15-30% of patients have synchronous endometrial hyperplasia or carcinoma; these tumors are often well differentiated with squamous metaplasia
  • Associated with keratin granulomas of peritoneum, which are devoid of viable cells; may contain ghosts of squamous cells or keratin debris
  • Search for viable tumor cells; but granulomas alone do not change stage or prognosis (Am J Surg Pathol 1990;14:925)
  • Mean age 51 years, range 26-87 years
  • Grading: similar to primary carcinomas in the endometrium
Prognostic Factors
  • Better than serous / mucinous tumors because usually stage 1 and well differentiated, but when matched for age, stage and grade, prognosis is similar to serous
  • Cytologic atypia and microinvasion do not appear to affect prognosis (Am J Surg Pathol 2000;24:1465)
  • Prognosis not as good as borderline tumors; may have malignant behavior if limited destructive stromal invasion (Mod Pathol 2005;18:903)
  • Sample thoroughly, as serous or undifferentiated carcinoma component lowers 5 year survival from 63% (pure) to 8% (Am J Surg Pathol 1994;18:687)
  • Tumors with yolk sac component are unusually aggressive (Am J Surg Pathol 1996;20:1056)
Gross Description
  • Cystic, solid, hemorrhagic
  • Papillary formations are absent or inconspicuous
  • 5% bilateral
  • Mean 11 cm, range 3-22 cm
Gross Images

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Surface of ovary and opened uterus

Arising in endometriotic cyst



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Focal necrosis

Micro Description
  • Either non-cystic villoglandular pattern, glandular confluence or stromal disappearance
  • Stromal invasion is defined as confluent glandular growth, stromal disappearance or obvious stromal invasion
  • Resembles endometrioid adenocarcinoma of endometrium, usually well differentiated
  • 50% have squamous metaplasia (morules or keratin pearls, formerly called adenoacanthomas), 40% of well differentiated tumors have adenofibromatous component
  • 10% are associated with luteinized stroma cells
  • May contain luminal but not cytoplasmic mucin, may have clear cells (but lacks the architecture of clear cell carcinoma, Am J Surg Pathol 2007;31:1203)
  • Vascular invasion rare
Micro Images

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Images hosted on PathOut server:

Various images


With squamous differentiation


Oxyphilic variant

Ciliated cell variant

Secretory variant


Foreign body giant cell reaction

Lining endometriotic cyst



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Destructive invasion

Villoglandular pattern

Squamous metaplasia


Various images

Positive Stains
Molecular / Cytogenetics Description
  • PTEN mutations in 21%
Electron Microscopy Description
  • Paranuclear microfilaments, "mesh basket" nucleoli
Differential Diagnosis
  • Granulosa cell or Sertoli-Leydig tumors: usually younger patients with endocrine symptoms, no squamous metaplasia, no typical endometrioid features elsewhere, no mucin, no adenofibroma component, keratin negative
  • Metastatic colonic carcinoma: dirty necrosis, garland pattern, CDX2+, CK20+
  • Metastatic endometrial carcinoma: high grade, bilateral, multinodular, surface implants, prominent angiolymphatic invasion within ovarian stroma
  • Mixed endometrioid and mucinous ovarian carcinoma: > 10% mucinous component
  • Yolk sac tumors