Endometrial polyp with atypical stromal cells

Topic Completed: 1 June 2016

Minor changes: 2 July 2021

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PubMed search: Endometrial polyp atypical stromal cells

Vijay Shankar, M.D.
Carlos Parra-Herran, M.D.
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Cite this page: Shankar V. Endometrial polyp with atypical stromal cells. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/uteruspolypatypical.html. Accessed August 2nd, 2021.
Definition / general
Clinical features
  • Mean age 56 years (range 45 - 82 years)
  • Patients present with abnormal bleeding or post-menopausal bleeding attributed to an endometrial polyp (confirmed by ultrasonography or hysteroscopy)
Prognosis and treatment
  • Although studies with follow-up are limited, behavior appears to be indolent with no recurrences or progression to malignancy reported, even in cases treated only with curettage / polypectomy
  • Simple curettage or biopsy may be sufficient, but due to paucity of published reports, follow up is necessary
Gross description
  • Macroscopically, endometrial polyps harboring atypical stromal cells are indistinct from conventional polyps
Microscopic (histologic) description
  • Conventional endometrial, endocervical or adenomyomatous pedunculated or sessile lesion with histologic features diagnostic of polyp
  • Atypical cells have the following characteristics:
    • Atypia is defined as nuclear enlargement and hyperchromasia compared to normal endometrial stroma
      • Nuclear enlargement ranges from minimal to marked
      • Chromatin distribution is uniform with a "smudged" appearance (instead of coarse)
      • Multinucleated forms can be seen
    • There is NO mitotic activity
    • Distribution:
      • Focally scattered throughout the polyp, predominantly beneath the surface epithelium or at the base
      • In most cases distribution is focal to multifocal
      • Diffuse distribution occurs in a minority
    • No prominent nucleoli are seen
Microscopic (histologic) images

AFIP images

Endometrial polyp with pseudosarcomatous stromal atypia: lesion is polypoid; large, often
multinucleatedcells with large hyperchromatic nuclei are present; these findings were limited to this
polyp in a hysterectomy specimen, and mitotic figures were absent; the lesion never became more
cellular than in this field; no densely cellular cuffs were noted around endometrial glands

Images hosted on other servers:

Bizzare stromal cells in endometrial polyp in a postmenopausal woman (fig 3)

Positive stains
Differential diagnosis
  • Adenosarcoma: Extent of stromal atypia is greater (usually diffuse or multifocal), atypia is uniformly severe, stromal hypercellularity, periglandular stromal cuffing, cambium layer underneath the glandular component, leaf-like projections into glandular lumina and > 3 mitoses / 10 high power fields
  • Trophoblastic cells: Location is important (implantation site nodule or recent implantation site instead of a polyp). Cells dispersed individually or in loose aggregates, surrounded by fibrinoid material. Mononuclear trophoblast cells have polygonal shape, abundant pale eosinophilic cytoplasm and round uniform nuclei.Sincytiotrophoblast is characteristically multinucleated
  • Endometrial stromal sarcoma: Expansile proliferation of spindle cells resembling endometrial stroma (usually producing a mass effect, instead of atypical cells in polyps which are usually incidental), tightly packed uniform spindled cells without significant glandular elements, smaller capillary type vessels distributed evenly; infiltrates into myometrium
  • MMMT: Malignant appearing epithelial component, stromal component shows diffuse severe atypia and is mitotically active
Additional references
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