Definition/General
Introduction:
Fallopian tube endometriosis represents the presence of endometrial glands and stroma within the wall of the fallopian tube
It is a relatively uncommon site of endometriosis compared to ovaries and pelvis
It accounts for 5-10% of all endometriosis cases
It can cause tubal dysfunction and infertility.
Origin:
Results from retrograde menstruation through fimbrial ends
May arise from metaplastic transformation of coelomic epithelium
Lymphatic or hematogenous spread from other endometrial foci
Direct implantation during surgical procedures
Müllerian remnants theory explains some cases.
Classification:
Classified by depth of involvement: superficial (serosal)
Deep (intramural)
Based on morphology: typical endometriosis (glands and stroma)
Stromal endometriosis (stroma only)
Atypical endometriosis (architectural atypia)
Inactive vs active based on hormonal response.
Epidemiology:
Affects women of reproductive age (20-45 years)
Peak incidence in 3rd and 4th decades
Associated with primary infertility (30-50% cases)
More common in nulliparous women
Genetic predisposition in some families
Higher prevalence in developed countries.
Clinical Features
Presentation:
Chronic pelvic pain (most common)
Dysmenorrhea (cyclic pelvic pain)
Infertility (primary or secondary)
Dyspareunia
Abnormal uterine bleeding
Cyclical symptoms related to menstruation
May be asymptomatic.
Symptoms:
Pelvic pain (worse during menstruation)
Dysmenorrhea (severe menstrual cramps)
Chronic fatigue
Painful intercourse
Infertility (difficulty conceiving)
Irregular menstrual cycles
Ovarian cysts (endometriomas).
Risk Factors:
Nulliparity
Short menstrual cycles (<27 days)
Early menarche (<12 years)
Late menopause
Family history of endometriosis
Müllerian anomalies
Previous pelvic surgery
Immune dysfunction
Environmental factors.
Screening:
Pelvic examination for masses and tenderness
Transvaginal ultrasonography
MRI for deep endometriosis
CA-125 levels (elevated but non-specific)
Laparoscopy for definitive diagnosis
Hysterosalpingography for tubal patency.
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Gross Description
Appearance:
Fallopian tubes may appear normal externally in early stages
Blue-black nodules or chocolate cysts on serosal surface
Adhesions to surrounding structures
Thickening of tubal wall
Distortion of normal anatomy.
Characteristics:
Hemorrhagic foci visible as dark spots
Fibrotic areas causing tubal stiffness
Adhesions between tube and ovary
Cut surface shows cystic spaces with dark content
Scarring and tissue distortion
Size varies from microscopic to several centimeters.
Size Location:
Most commonly affects distal fallopian tube near fimbria
Bilateral involvement in 60-70% of cases
Size ranges from microscopic foci to large masses
Intramural location most common
May involve entire tube length.
Microscopic Description
Histological Features:
Endometrial glands lined by columnar epithelium
Endometrial stroma surrounding glands
Hemosiderin-laden macrophages
Chronic inflammation
Fibrosis and smooth muscle hyperplasia
Hemorrhage and necrosis.
Cellular Characteristics:
Glandular epithelium shows columnar cells with oval nuclei
Stromal cells resemble endometrial stroma
Mitotic activity varies with menstrual cycle
Hemosiderin deposits from recurrent bleeding
Inflammatory cells including lymphocytes and plasma cells.
Architectural Patterns:
Tubular glands within tubal wall
Cystic dilatation of glands
Stromal proliferation around glands
Smooth muscle metaplasia
Fibrotic reaction with collagen deposition
Loss of normal tubal architecture.
Immunohistochemistry
Positive Markers:
CD10 positive in endometrial stroma
ER and PR positive in glands and stroma
Vimentin positive in stromal cells
PAX8 positive in glandular epithelium
CK7 positive in epithelial cells.
Negative Markers:
CD117 negative (helps exclude GIST)
S-100 negative in most cells
p63 negative in glandular epithelium
Calretinin negative (helps exclude mesothelial proliferation)
WT1 negative in most cases.
Diagnostic Utility:
CD10 is highly specific for endometrial stroma
ER/PR confirm hormonal responsiveness
Helps distinguish from other cystic lesions
Useful in cases with extensive fibrosis
PAX8 supports müllerian origin.
Molecular/Genetic
Differential Diagnosis
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
Fallopian tube specimen, [side], measuring [dimensions]
Clinical History
Clinical presentation: [pelvic pain/infertility/dysmenorrhea], duration: [time period]
Macroscopic Examination
Fallopian tube shows [normal appearance/blue-black nodules/adhesions], cut surface reveals [cystic spaces/hemorrhagic foci]
Microscopic Examination
Shows endometrial glands and stroma within tubal wall with [hemosiderin-laden macrophages/chronic inflammation/fibrosis]
Immunohistochemistry
CD10: [positive] in stromal cells, ER/PR: [positive] in glands and stroma
Extent of Involvement
[Superficial/Deep/Transmural] involvement of [location within tube]
Diagnosis
Endometriosis of fallopian tube, [degree of involvement]
Recommendations
Clinical correlation, hormonal therapy consideration, fertility assessment if indicated