Definition/General

Introduction:
-Endometrial Polyp is a benign, localized overgrowth of endometrial tissue
-It consists of endometrial glands and stroma projecting into the uterine cavity
-It has a fibrovascular core and surface epithelium
-Polyps are hormone-responsive and may cause abnormal bleeding.
Origin:
-Arises from the basalis layer of the endometrium
-Results from localized hyperplasia of endometrial glands and stroma
-Associated with hormonal stimulation
-Contains thick-walled blood vessels
-May contain functional and basalis type endometrium.
Classification:
-Functional polyps: Responsive to hormonal changes
-Basalis polyps: Non-responsive to hormones
-Hyperplastic polyps: With hyperplastic glands
-Atrophic polyps: In postmenopausal women
-Malignant transformation: Rare (<1-3%).
Epidemiology:
-Common in reproductive age and postmenopausal women
-Peak incidence in 4th-5th decades
-Prevalence 10-40% in women with abnormal bleeding
-Associated with obesity and unopposed estrogen
-Tamoxifen therapy increases risk
-Higher prevalence in infertile women.

Clinical Features

Presentation:
-Abnormal uterine bleeding (most common)
-Intermenstrual bleeding
-Postmenopausal bleeding (20-30%)
-Heavy menstrual bleeding
-Infertility (mechanical obstruction)
-Asymptomatic (incidental finding)
-Pelvic pain (less common).
Symptoms:
-Irregular bleeding (80-90% symptomatic cases)
-Heavy menstrual bleeding
-Spotting between periods
-Postcoital bleeding
-Chronic pelvic pain
-Dysmenorrhea
-Infertility or recurrent pregnancy loss
-Pressure symptoms (large polyps).
Risk Factors:
-Age (perimenopausal/postmenopausal)
-Obesity (BMI >25)
-Hypertension
-Tamoxifen therapy
-Unopposed estrogen therapy
-Lynch syndrome
-Previous endometrial pathology
-PCOS
-Diabetes mellitus.
Screening:
-Transvaginal ultrasound (first-line imaging)
-Saline infusion sonohysterography (SIS)
-Hysteroscopy (gold standard)
-Endometrial biopsy for tissue diagnosis
-MRI for complex cases
-3D ultrasound for better visualization
-Office hysteroscopy for direct visualization.

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Gross Description

Appearance:
-Smooth, rounded masses projecting into uterine cavity
-Pink to tan-colored surface
-May be pedunculated or sessile
-Size ranges from few millimeters to several centimeters
-Soft, fleshy consistency
-May show surface ulceration or hemorrhage.
Characteristics:
-Well-circumscribed polypoid masses
-Smooth or lobulated surface
-May contain cystic areas
-Cut surface shows spongy texture
-Visible blood vessels in stalk
-May show surface fibrin or necrosis.
Size Location:
-Size varies from 2mm to >5cm
-Commonly arise from fundus or body
-May originate from cornual regions
-Multiple polyps in 20-25% cases
-Can extend through cervical os
-Large polyps may fill entire cavity.
Multifocality:
-Single polyp most common (75-80%)
-Multiple polyps in 20-25% cases
-May be associated with diffuse endometrial hyperplasia
-Can occur with submucosal fibroids
-Risk of recurrence after incomplete removal
-Associated with adenomyosis in some cases.

Microscopic Description

Histological Features:
-Surface epithelium similar to endometrium
-Endometrial glands in various phases
-Endometrial stroma with spindle cells
-Thick-walled blood vessels characteristic
-Fibrovascular core
-May show surface ulceration
-Chronic inflammation possible.
Cellular Characteristics:
-Benign epithelial cells lining glands
-Ciliated and non-ciliated cells
-Spindle-shaped stromal cells
-Smooth muscle cells around vessels
-No significant atypia
-Mitotic activity variable with cycle
-Inflammatory cells possible.
Architectural Patterns:
-Irregular gland distribution
-Cystically dilated glands common
-Surface papillary projections
-Branching fibrovascular cores
-May show secretory changes
-Metaplastic changes possible
-Hyperplastic glands in some polyps.
Grading Criteria:
-Benign polyps: No atypia, regular architecture
-Hyperplastic polyps: Glandular hyperplasia without atypia
-Atypical polyps: Nuclear atypia present (<1% cases)
-Malignant polyps: Adenocarcinoma arising in polyp (rare)
-Assessment of surface integrity.

Immunohistochemistry

Positive Markers:
-ER positive (usually strong)
-PR positive (variable with cycle)
-CD10 positive (endometrial stroma)
-Smooth muscle actin (vascular smooth muscle)
-CD34 (blood vessels)
-Vimentin positive (stromal cells)
-CK AE1/AE3 (epithelium).
Negative Markers:
-p53 wild-type (benign polyps)
-Ki-67 low proliferation index
-Calretinin negative (versus mesothelioma)
-WT1 negative (endometrial stroma)
-Smooth muscle markers in stroma (negative)
-Melanoma markers negative.
Diagnostic Utility:
-CD10 confirms endometrial stromal origin
-Smooth muscle actin highlights vascular component
-ER/PR confirms hormonal responsiveness
-Ki-67 low in benign polyps
-p53 wild-type pattern in benign cases
-Cytokeratin highlights epithelial component.
Molecular Subtypes:
-Hormone-responsive type (most common)
-Basalis type (hormone-independent)
-Hyperplastic type (with glandular hyperplasia)
-Atrophic type (postmenopausal)
-Inflammatory type (with chronic inflammation)
-Metaplastic type (with metaplastic changes).

Molecular/Genetic

Genetic Mutations:
-HMGA2 rearrangements (common in polyps)
-RAD51L1-HMGA2 fusions
-PTEN mutations (rare, in atypical polyps)
-KRAS mutations (uncommon)
-PIK3CA mutations (occasional)
-Beta-catenin mutations (rare).
Molecular Markers:
-HMGA2 overexpression
-Estrogen receptor expression
-Progesterone receptor expression
-Low Ki-67 proliferation
-Wild-type p53
-Intact mismatch repair proteins
-VEGF expression in vessels.
Prognostic Significance:
-Excellent prognosis for benign polyps
-Risk of malignant transformation <1-3%
-Recurrence rate 10-15% if incompletely removed
-Associated infertility resolves after removal
-Postmenopausal polyps higher malignancy risk
-Size >1.5cm associated with symptoms.
Therapeutic Targets:
-Hormonal manipulation: GnRH agonists
-Progestins (limited efficacy)
-Aromatase inhibitors (postmenopausal)
-Hysteroscopic removal (treatment of choice)
-Endometrial ablation (recurrent cases)
-Hysterectomy (complex cases).

Differential Diagnosis

Similar Entities:
-Submucosal fibroid
-Endometrial hyperplasia
-Adenofibroma
-Endometrial carcinoma
-Retained products of conception
-Adenosarcoma
-Prolapsed fallopian tube.
Distinguishing Features:
-Endometrial polyp: Endometrial glands and stroma
-Submucosal fibroid: Smooth muscle component
-Adenofibroma: Phyllodes-like architecture
-Endometrial carcinoma: Nuclear atypia and invasion
-RPOC: Chorionic villi
-Adenosarcoma: Stromal atypia and mitoses.
Diagnostic Challenges:
-Distinguishing from submucosal fibroid
-Fragmented specimens
-Atypical polyps versus adenocarcinoma
-Hyperplastic polyps versus diffuse hyperplasia
-Secondary changes (hemorrhage, necrosis)
-Adenosarcoma in elderly women.
Rare Variants:
-Adenofibroma with benign stroma
-Atypical polypoid adenomyoma
-Tamoxifen-associated polyps
-Polyps with squamous metaplasia
-Polyps with ciliated cell metaplasia
-Polyps with clear cell change.

Sample Pathology Report

Template Format

Sample Pathology Report

Complete Report: This is an example of how the final pathology report should be structured for this condition.

Patient Information

Name: [Patient Name]\nAge: [X] years\nMRN: [Medical Record Number]\nDate of Procedure: [Date]

Clinical History

Clinical indication: [Abnormal uterine bleeding/Postmenopausal bleeding/Infertility workup/Other]\nImaging findings: [Ultrasound/MRI findings if available]\nProcedure: [Hysteroscopic polypectomy/Dilatation and curettage]

Specimen Received

Specimen type: Endometrial polyp\nSpecimen container: [Single/Multiple] container(s)\nFixative: 10% neutral buffered formalin

Gross Examination

The specimen consists of [single/multiple] tan-pink, polypoid tissue fragment(s) measuring up to [X] cm in greatest dimension. The polyp(s) have a [smooth/lobulated] surface and [soft/firm] consistency. Cut surface reveals a [spongy/solid] appearance with visible blood vessels. The specimen is entirely submitted for histological examination in [X] cassettes.

Microscopic Examination

Sections show a benign endometrial polyp composed of endometrial glands and stroma with a characteristic fibrovascular core. The surface is lined by benign endometrial epithelium. The glands show [regular/irregular] distribution and are lined by [ciliated and non-ciliated/secretory/atrophic] epithelium without nuclear atypia. The stroma contains spindle-shaped cells and prominent thick-walled blood vessels. [Surface ulceration/hemorrhage/chronic inflammation] is [present/absent]. Background endometrium shows [proliferative/secretory/atrophic] pattern.

Final Diagnosis

BENIGN ENDOMETRIAL POLYP\n\nSize: [X] cm\nNumber: [Single/Multiple]\nType: [Functional/Basalis/Hyperplastic/Atrophic]\nSurface integrity: [Intact/Ulcerated]

Comments

• Benign endometrial polyp with no evidence of atypia or malignancy.\n• Complete hysteroscopic removal is typically curative.\n• Risk of malignant transformation is very low (<1-3%).\n• Follow-up recommended for symptom resolution.\n• Consider evaluation for underlying causes if polyps are recurrent.

Reported By

Dr. [Pathologist Name], MD\nConsultant Pathologist\nDate: [Report Date]