Definition/General
Introduction:
Endometriotic ascites results from ectopic endometrial tissue in peritoneal cavity
Caused by retrograde menstruation or endometrioma rupture
Contains endometrial glands and stroma
Cyclic symptoms related to menstrual cycle
Chocolate-colored fluid characteristic.
Origin:
Results from Sampsons theory (retrograde menstruation)
Coelomic metaplasia theory
Endometrioma rupture
Lymphatic/hematogenous spread
Iatrogenic implantation during surgery.
Classification:
Classified by rASRM staging
Stage I (minimal)
Stage II (mild)
Stage III (moderate)
Stage IV (severe)
Based on extent and depth of implants.
Epidemiology:
Affects 6-10% of reproductive-age women
Peak incidence 25-35 years
Infertility association in 30-50% cases
Familial clustering observed
Higher in nulliparous women.
Clinical Features
Presentation:
Cyclic pelvic pain
Dysmenorrhea
Dyspareunia
Infertility
Acute abdomen (rupture)
Chocolate-colored ascites.
Symptoms:
Cyclic pelvic pain (85% cases)
Dysmenorrhea (70% cases)
Dyspareunia (60% cases)
Infertility (40% cases)
Dyschezia (30% cases)
Chronic fatigue (25% cases).
Risk Factors:
Reproductive age
Nulliparity
Early menarche
Short menstrual cycles
Family history
Mullerian anomalies
Delayed childbearing.
Screening:
Transvaginal ultrasound
CA-125 levels (elevated during menstruation)
MRI pelvis
Laparoscopy (gold standard)
Histopathological confirmation.
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Gross Description
Appearance:
Ascitic fluid has chocolate-brown color
Thick, viscous consistency
Old blood appearance
Hemosiderin-laden
May clot due to fibrin.
Characteristics:
Hemorrhagic with old blood
Elevated protein content
Hemoglobin degradation products
CA-125 elevated
Iron deposits.
Size Location:
Localized collections
Pouch of Douglas
Ovarian fossa
Paracolic gutters
Pelvic sidewalls.
Multifocality:
Multiple pelvic implants
Ovarian endometriomas
Uterosacral ligament involvement
Rectovaginal septum
Peritoneal surfaces.
Microscopic Description
Histological Features:
Ascitic fluid contains endometrial epithelial cells
Endometrial stromal cells
Hemosiderin-laden macrophages
Reactive mesothelial cells
Mixed inflammatory cells.
Cellular Characteristics:
Endometrial glandular epithelium
Stromal cells with spindle morphology
Hemosiderin-laden macrophages
Reactive mesothelial proliferation
Chronic inflammatory cells.
Architectural Patterns:
Glandular fragments
Stromal clusters
Hemosiderin deposits
Mesothelial hyperplasia
Inflammatory background.
Grading Criteria:
No specific grading system
Presence of endometrial elements
Hemosiderin-laden macrophages
Cyclic changes may be observed
Hormonal responsiveness.
Immunohistochemistry
Positive Markers:
ER, PR in endometrial cells
CD10 in endometrial stroma
CK7 in glandular epithelium
CD68 in hemosiderin-laden macrophages
Calretinin in reactive mesothelial cells.
Negative Markers:
WT1 (helps distinguish from mesothelial)
CEA (excludes adenocarcinoma)
TTF-1 (excludes lung primary)
PAX8 variable in endometrial cells.
Diagnostic Utility:
ER/PR positivity confirms endometrial origin
CD10 identifies endometrial stroma
Panel approach helpful for diagnosis
Distinguishes from malignancy.
Molecular Subtypes:
Hormone-responsive tissue
Estrogen-dependent growth
Progesterone effects
Aromatase expression in ectopic endometrium.
Molecular/Genetic
Genetic Mutations:
ARID1A mutations in some cases
PIK3CA mutations
KRAS mutations
TP53 mutations (rare)
PTEN loss in atypical cases.
Molecular Markers:
CA-125 elevated (especially during menstruation)
CA 19-9 may be elevated
Aromatase activity increased
Inflammatory mediators elevated.
Prognostic Significance:
Benign condition overall
Malignant transformation rare (<1%)
Clear cell and endometrioid carcinoma risk
Fertility implications
Quality of life impact.
Therapeutic Targets:
Hormonal therapy: GnRH agonists, progestins
NSAIDs for pain management
Surgical resection
Assisted reproductive technology
Aromatase inhibitors.
Differential Diagnosis
Similar Entities:
Hemorrhagic ovarian cyst rupture
Malignant ascites
Inflammatory ascites
Reactive mesothelial proliferation
Adenomatoid tumor.
Distinguishing Features:
Endometriosis: ER/PR positive glands
Endometriosis: CD10 positive stroma
Hemorrhagic cyst: No endometrial elements
Malignant: Cytological atypia
Reactive: Mesothelial markers only.
Diagnostic Challenges:
Reactive mesothelial proliferation may mimic glands
Hormonal effects on morphology
Processing artifacts
Sampling adequacy
Cyclic variations.
Rare Variants:
Atypical endometriosis
Deep infiltrating endometriosis
Malignant transformation
Extraperitoneal endometriosis
Thoracic endometriosis.
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.
Specimen Information
Peritoneal fluid, volume [X] mL, chocolate-brown, viscous
Adequacy
Adequate for cytological evaluation
Cellularity
Moderate cellularity with [X] cells/μL
Morphological Features
Endometrial glandular epithelium and stromal cells present. Hemosiderin-laden macrophages noted. Background shows hemorrhage and inflammatory cells.
Endometrial Elements
Endometrial glands and stroma identified
Immunohistochemistry
ER: [Result], PR: [Result], CD10: [Result] (stroma), CK7: [Result] (glands)
Malignant Cells
No malignant cells identified
Final Diagnosis
Peritoneal fluid with endometrial tissue - consistent with endometriosis
Comment
Findings consistent with peritoneal endometriosis. Clinical correlation with symptoms and imaging recommended. Hormonal therapy may be beneficial.