Benign endometrial polyp

Benign endometrial polyp, abbreviated BEP, is a common diagnosis is endometrial specimens.

Benign endometrial polyp
Diagnosis in short
Endometrial polyp. H&E stain.
LM	large blood vessels (muscular), fibrotic stroma, polypoid shape (epithelium on three sides), +/-gland dilation
LM DDx	adenofibroma, cervical polyp - have endocervical mucosa, lower uterine segment, endometrial carcinoma
Gross	polypoid mass in the endometrial cavity
Associated Dx	invasive breast cancer - specifically assoc. with tamoxifen
Clinical history	bleeding
Prevalence	common
Prognosis	benign

Uterine polyp redirects here.

It is also simply known as endometrial polyp which is a somewhat ambiguous descriptor as not all endometrial polyps are benign.

General

• Very common.
• May be a cause of menorrhagia (heavy & long menses).

Gross

• Polypoid mass in the endometrial cavity.

Gross DDx:

• Secretory phase endometrium.
• Pedunculated leiomyoma.

Microscopic

Features - diagnostic criteria:

1. Large blood vessels (muscular) - key feature.
2. Fibrotic stroma - key feature.
3. Polypoid shape - epithelium on three sides.
   • May not be seen... as polyp is fragmented on removal.

Glandular changes common:

• Endometrial glands may be out of phase with surrounding endometrium.
  • Often proliferative.
• +/-Cystic dilation of glands/unusual shapes
  • Simple endometrial hyperplasia should not be diagnosed in a polyp!
• +/-Focal gland crowding.

Notes:

1. Apparently benign polyps should be examined closely at the surface for in situ & invasive malignancies.
2. Stroma often cellular.

DDx:

• Adenofibroma.
• Cervical polyp - have endocervical mucosa.
• Lower uterine segment - have endocervical epithelium and lack the thick-walled blood vessels.
• Endometrial carcinoma - esp. serous carcinoma of the endometrium.

Sign out

Non-proliferative

ENDOMETRIUM, CURETTAGE:
- BENIGN ENDOMETRIAL POLYP.

ENDOMETRIUM ("POLYPS"), REMOVAL:
- BENIGN ENDOMETRIAL POLYPS WITH CYSTIC GLANDULAR DILATION AND
WITHOUT APPARENT PROLIFERATIVE ACTIVITY. 

Suggestive of polyp

ENDOMETRIUM, CURETTAGE:
- POLYPOID NONPROLIFERATIVE ENDOMETRIUM WITH FOCALLY PROMINENT SMALL BLOOD VESSELS AND
  FIBROUS STROMA, SUGGESTIVE OF BENIGN POLYP.
- NEGATIVE FOR HYPERPLASIA AND NEGATIVE FOR MALIGNANCY.

Proliferative

ENDOMETRIUM, CURETTAGE:
- BENIGN ENDOMETRIAL POLYP WITH PROLIFERATIVE ACTIVITY.

Note:

• It is useful to comment on whether non-polypoid endometrium is proliferative (if present), esp. in menopausal women.

Polyp with disordered proliferative phase in the background

ENDOMETRIUM, BIOPSY:
- BENIGN ENDOMETRIAL POLYP WITH PROLIFERATIVE GLANDS AND FOCAL GLAND DILATION.
- SUSPICIOUS FOR A BACKGROUND OF DISORDERED PROLIFERATIVE
  PHASE ENDOMETRIUM, SEE COMMENT.
- STRIPPED BENIGN ENDOCERVICAL EPITHELIUM.

COMMENT:
The endometrium sampled is proliferative with focal gland dilation throughout. The
features of a polyp (large muscular blood vessels, fibrous stroma and polypoid fragments of
endometrium) are only focally present, suggesting there is a background of disordered
proliferative phase endometrium.  Clinical correlation is suggested.

Clinically a polyp but not apparent on histology

 UTERUS (POLYP), REMOVAL:
- LARGE FRAGMENT OF SECRETORY PHASE ENDOMETRIUM WITH LARGE BLOOD VESSELS, A
  NON-FIBROUS STROMA AND NO DISCERNIBLE SURFACE EPITHELIUM.

See also

• Endometrium.