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Ovary tumor
Serous tumors
Peritoneal implants


Topic Completed: 1 June 2012

Revised: 10 September 2019

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PubMed Search: extraovarian implants

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Table of Contents
Definition / general | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Differential diagnosis
Cite this page: Ehdaivand S. Peritoneal implants. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/ovarytumorovarianimplants.html. Accessed February 21st, 2020.
Definition / general
  • In patients with primary ovarian tumors, implants are deposits of ovarian tumor on peritoneal surfaces, lateral pelvic gutters, right side of diaphragm or omentum, usually close to primary
  • Entire peritoneum may contain tumor nodules < 1 cm, resembling miliary tuberculosis
  • Implants are seen in 1/3 of patients with serous borderline tumors, mortality is 25%; some may arise from peritoneal mesothelium; destructive invasion and cytologic atypia are associated with disease progression
  • May regress spontaneously leaving psammoma bodies behind

  • Criteria:
    • Ovarian carcinoma if multiple peritoneal nodules with features of ovarian serous borderline tumor or carcinoma and some minimal ovarian involvement
    • Extraovarian serous carcinoma or papillary tumor of peritoneum if no ovarian involvement

  • Criteria for implants associated with primary benign or borderline tumor:
    • Invasive: either invasion of underlying normal tissue with infiltrating margin and desmoplastic stroma that resembles low-grade serous carcinoma OR micropapillary architecture or solid epithelial nests surrounded by cleft
    • Noninvasive: resembles borderline serous tumor, within submesothelial invaginations and between adipose tissue lobules, or within reactive fibrous stroma with variable inflammation

  • Invasion by these criteria is associated with adverse outcome (Am J Surg Pathol 2001;25:419)
  • Features that do not correlate with invasion are nuclear atypia, mitoses, calcification, necrosis, and individual cell infiltration of the stroma
Microscopic (histologic) description
  • Tufting, stratification, atypia, psammoma bodies
  • Invasive cases can have micropapillary pattern and solid epithelial nests surrounded by clefts
Microscopic (histologic) images

Images hosted on PathOut server:

Between lobules of greater omentum

Coats the surface of omentum and extends as septum between adjacent lobules

Massive necrosis

Disorderly groups of tumor cells lie in dense, focally hemorrhagic stroma


Desmoplastic implant invades omental tissue in irregular fashion

Resembles grade 1 serous carcinoma

Desmoplastic noninvasive implant

Positive stains
  • LeuM1, B72.3, CEA
Differential diagnosis
  • Benign inclusions: less epithelial proliferation
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