Benign endometrial polyp

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

Benign endometrial polyp
Diagnosis in short
Endometrial polyp (right - fibrotic stroma). 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, simple endometrial hyperplasia, disordered proliferative endometrium
Gross	polypoid mass in the endometrial cavity
Site	endometrium
Associated Dx	invasive breast cancer - specifically assoc. with tamoxifen
Clinical history	bleeding (menorrhagia)
Prevalence	common
Prognosis	benign
Clin. DDx	leiomyoma, other polypoid masses

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).
• Malignant endometrial polyps are uncommon <2% in one series, and typically in post-menupausal women (3.6% versus 0.5%).

Gross

• Polypoid mass in the endometrial cavity.

Notes:

• May be large - 10 cm.

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.
• Simple endometrial hyperplasia.
• Disordered proliferative endometrium.

Images

• 

  Endometrial polyp - low mag. (WC)

• 

  Endometrial polyp - intermed. mag. (WC)

• 

  Endometrial polyp - intermed. mag. (WC)

• 

  Endometrial polyp - low mag. (WC)

IHC

• p16 stroma usually +ve.

Sign out

Non-proliferative

ENDOMETRIUM, CURETTAGE:
- BENIGN ENDOMETRIAL POLYP.

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

Extensive surface denudation

POLYP, ENDOMETRIUM, REMOVAL:
- BENIGN LARGE ENDOMETRIAL POLYP WITH EXTENSIVE DENUDATION OF THE SURFACE
  AND INFLAMMATION, WITHOUT APPARENT PROLIFERATIVE ACTIVITY.
- BLOOD (ABUNDANT), FIBRIN AND CELLULAR DEBRIS.

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.