Cervical & Endometrial Pathology
Pathology · Neoplasia · lean revision notes
Cervical & Endometrial Pathology
High-yield gynaecological pathology spanning two of the commonest female genital tract cancers. The molecular targets of HPV oncoproteins, the squamocolumnar junction, Pap-smear grading and the Type I vs Type II split of endometrial carcinoma generate dense, repeatable NEET PG single-best-answer questions.
1. Cervix — anatomy & the transformation zone
The cervix has two epithelial compartments:
- Ectocervix — non-keratinising stratified squamous epithelium (continuous with the vagina).
- Endocervix — single layer of mucus-secreting columnar epithelium lining the canal and crypts.
The abrupt junction between them is the squamocolumnar junction (SCJ). With puberty, pregnancy and oral contraceptives the columnar epithelium everts onto the ectocervix (ectropion), is exposed to the acidic vaginal pH and undergoes squamous metaplasia. The dynamic region between the original and the new SCJ is the transformation zone (TZ) — and almost every cervical neoplasm and HPV infection arises here, because actively dividing metaplastic basal cells are the cells HPV infects.
High-yield: The transformation zone is the site of origin of cervical carcinoma. Pap smear and colposcopic sampling must capture the TZ to be adequate.
2. HPV — the central oncogenic event
Persistent infection with high-risk human papillomavirus (HR-HPV) is necessary for nearly all cervical squamous and most cervical adenocarcinomas. HPV is a double-stranded circular DNA virus.
| Risk group | Genotypes | Clinical association |
|---|---|---|
| High-risk (oncogenic) | 16, 18, 31, 33, 45, 52, 58 | CIN, cervical carcinoma; 16 → squamous cell ca; 18 → adenocarcinoma (more) |
| Low-risk | 6, 11 | Condyloma acuminatum (genital warts), low-grade lesions, laryngeal papillomatosis |
The two killer oncoproteins (must memorise)
When HPV DNA integrates into the host genome, the viral E2 repressor gene is disrupted, leading to unregulated overexpression of E6 and E7.
| Oncoprotein | Host target | Consequence |
|---|---|---|
| E6 | Binds and degrades p53 (via ubiquitin ligase E6-AP) | Loss of apoptosis, ↓ DNA-damage arrest, telomerase activation |
| E7 | Binds and inactivates RB (retinoblastoma protein) | Releases E2F → unchecked G1→S progression, proliferation |
High-yield (most-tested fact): E6 → degrades p53; E7 → inactivates RB. Mnemonic: "E6 Six = p53 (5+3=... think 'six sits on p53'); E7 seven → RB." Simpler — "6 before 7, p53 before RB" matching numeric order.
High-yield: HPV integration (not the episomal latent form) drives malignant transformation, and is the molecular tipping point from productive infection to neoplasia. p16^INK4a immunostain is a surrogate marker of HR-HPV E7 activity (block positivity = transforming infection).
Flow of carcinogenesis: HR-HPV infects TZ basal cells → episomal replication (productive, koilocytes) → viral integration → E2 loss → ↑E6/E7 → p53 ↓ + RB ↓ → genomic instability → CIN 1 → CIN 2 → CIN 3 → invasive carcinoma.
3. Cervical intraepithelial neoplasia (CIN) — grading
CIN reflects the proportion of epithelial thickness replaced by atypical, immature, mitotically active cells (dysplasia confined above the basement membrane = pre-invasive).
| Grade (CIN) | Bethesda cytology | Epithelial thickness involved | Behaviour |
|---|---|---|---|
| CIN 1 | LSIL | Lower 1/3 | Mostly HPV cytopathic effect; ~60% regress |
| CIN 2 | HSIL | Lower 2/3 | Intermediate; treat |
| CIN 3 / CIS | HSIL | >2/3 to full thickness | High progression risk; treat |
- LSIL (low-grade squamous intraepithelial lesion) = CIN 1 + koilocytic atypia → reflects productive HPV infection; large majority regress.
- HSIL (high-grade) = CIN 2 + CIN 3 → reflects transforming infection; true precursor of carcinoma.
- Koilocyte = the pathognomonic HPV cell: enlarged nucleus, irregular hyperchromatic ("raisinoid") nuclear membrane, and a perinuclear clear halo.
High-yield: Koilocytosis is the morphological hallmark of HPV. It is most prominent in LSIL/CIN 1.
4. Cervical carcinoma
Epidemiology & risk factors
Second–third commonest cancer in Indian women. Risk factors all funnel into HPV exposure/persistence: early age at first intercourse, multiple partners, multiparity, smoking, immunosuppression (HIV), long-term OCP use, and lack of screening.
Histological types
| Type | Frequency | Notes |
|---|---|---|
| Squamous cell carcinoma | ~70–80% | Most common; from TZ; HPV-16 predominant |
| Adenocarcinoma | ~15–20%, rising | From endocervical glands; HPV-18; harder to screen by Pap (glandular) |
| Adenosquamous / small-cell | Few % | Aggressive |
Clinical features
Often asymptomatic when pre-invasive (hence screening). Invasive disease → post-coital bleeding, intermenstrual or postmenopausal bleeding, foul vaginal discharge. Advanced: pelvic pain, lateral spread to ureters → hydronephrosis and uraemia (commonest cause of death), bladder/rectal fistulae.
High-yield: Cervical cancer is clinically staged (FIGO) — historically the only major gynae cancer staged clinically, though imaging is now incorporated. Death is most often from renal failure due to bilateral ureteric obstruction.
Spread
Predominantly direct local extension (parametrium, vagina, bladder, rectum) and lymphatic. Haematogenous spread is late.
5. Screening & diagnosis — the investigation ladder
Stepwise approach:
- Pap smear (cytology) — screening; conventional or liquid-based (LBC). Sample the TZ.
- HPV DNA testing — now preferred primary screen (high sensitivity); co-testing with cytology in many guidelines.
- Colposcopy with acetic acid (aceto-white areas) and Schiller / Lugol's iodine (dysplastic/glycogen-poor areas stay unstained — Schiller positive).
- Colposcopy-directed biopsy — gold standard / confirmatory (histology).
- Endocervical curettage / cone biopsy (LEEP) if lesion extends into canal or for excision.
| Modality | Role | Key point |
|---|---|---|
| Pap smear | Screening | Detects dysplasia; reduced mortality dramatically |
| HPR-HPV DNA / mRNA | Primary screen | Most sensitive; high NPV |
| Colposcopy + biopsy | Confirmatory | Definitive diagnosis |
| p16/Ki-67 dual stain | Triage | Distinguishes transforming HSIL |
High-yield: Screening recommendation (simplified): begin around age 21–25 (or 30 for HPV primary), Pap every 3 years, or HPV testing every 5 years. Colposcopy-directed biopsy is the confirmatory investigation of choice, NOT the Pap smear.
High-yield — prevention: HPV vaccine (bivalent 16/18, quadrivalent 6/11/16/18, nonavalent) is prophylactic, given ideally before sexual debut (9–14 yrs). It does not treat established infection.
Management snapshot
- CIN 1 → often observe (regresses); persistent → ablation.
- CIN 2/3 (HSIL) → excision/ablation — LEEP (LLETZ), cold-knife conisation, cryotherapy.
- Invasive (microinvasive IA1) → conisation/simple hysterectomy.
- IA2–IIA → radical hysterectomy (Wertheim) + pelvic lymphadenectomy ± chemoradiation.
- ≥IIB / locally advanced → concurrent chemoradiation (cisplatin-based) — drug of choice cisplatin.
6. Endometrial carcinoma — the Type I vs Type II dichotomy
Commonest invasive gynaecological malignancy in developed nations; rising in India. Presents classically as postmenopausal bleeding — a red-flag symptom mandating endometrial evaluation.
High-yield: Postmenopausal bleeding is endometrial carcinoma until proven otherwise. Investigation of choice → transvaginal ultrasound (endometrial thickness >4–5 mm abnormal) followed by endometrial biopsy / fractional curettage / hysteroscopy for tissue diagnosis (gold standard).
The two pathways (extremely high-yield comparison)
| Feature | Type I (Endometrioid) | Type II (Serous / Clear cell) |
|---|---|---|
| Frequency | ~80% | ~10–20% |
| Driver | Unopposed oestrogen | Oestrogen-independent, atrophic endometrium |
| Precursor | Endometrial hyperplasia (atypical) | Serous intraepithelial carcinoma (EIC) |
| Age | Peri-/early post-menopause (younger) | Older, postmenopausal (≥65) |
| Body habitus | Obese, diabetic, hypertensive | Thin |
| Histology | Endometrioid (gland-forming), well-differentiated | Papillary serous (psammoma bodies), clear cell |
| Grade/behaviour | Low grade, good prognosis | High grade, aggressive, early spread |
| Key mutations | PTEN (most common), PIK3CA, KRAS, ARID1A, microsatellite instability (MMR loss) | TP53 (>90%), HER2 |
High-yield: Type I → PTEN; Type II → p53. Type II serous carcinoma behaves like high-grade ovarian serous cancer and disseminates transcoelomically even when uterine invasion is minimal.
Risk factors for Type I (oestrogen excess)
"Mnemonic — the unopposed-oestrogen states": Obesity, Nulliparity, Diabetes, Hypertension, Early menarche/Late menopause, PCOS, oestrogen-only HRT, Tamoxifen (agonist on endometrium), oestrogen-secreting tumours (granulosa cell tumour), Lynch syndrome (HNPCC).
High-yield: Tamoxifen is anti-oestrogenic on breast but pro-oestrogenic on endometrium → increases endometrial carcinoma risk. Combined OCPs and multiparity are PROTECTIVE.
Endometrial hyperplasia (precursor of Type I)
WHO 2014 / EIN system:
- Hyperplasia without atypia — low cancer risk (~1–3%); often regresses with progestins.
- Atypical hyperplasia / Endometrial Intraepithelial Neoplasia (EIN) — high progression (~25–40%); harbours PTEN loss; treat (progestin or hysterectomy).
High-yield: Nuclear ATYPIA is the single most important predictor of progression to carcinoma in endometrial hyperplasia.
Staging & management
Endometrial carcinoma is surgically staged (FIGO).
- Mainstay → Total hysterectomy + bilateral salpingo-oophorectomy (TAH-BSO) ± lymph node assessment ± peritoneal washings.
- Adjuvant radiotherapy / chemotherapy by stage and grade.
- Fertility-sparing (selected early grade-1) → high-dose progestins.
7. Endometriosis & adenomyosis (frequent distractors)
Endometriosis = endometrial glands + stroma outside the uterus.
- Theories: Sampson's retrograde menstruation (most popular), coelomic metaplasia, lymphovascular dissemination.
- Commonest site: ovary → "chocolate cyst" (endometrioma). Others: pouch of Douglas, uterosacral ligaments, peritoneum.
- Triad: dysmenorrhoea, dyspareunia, infertility; "powder-burn" peritoneal deposits.
- Microscopy clue: 2 of 3 — glands, stroma, haemosiderin-laden macrophages.
- Malignant transformation risk → clear cell and endometrioid carcinoma of ovary.
Adenomyosis = endometrial tissue within the myometrium → bulky, globular, tender uterus; menorrhagia + dysmenorrhoea; diagnosed on MRI/histology.
| Feature | Endometriosis | Adenomyosis |
|---|---|---|
| Location | Outside uterus | Within myometrium |
| Classic patient | Younger, infertility | Older multipara |
| Uterus | Normal-sized | Diffusely bulky, tender |
| Imaging | Endometrioma (USG) | MRI: junctional zone >12 mm |
High-yield: Ovarian "chocolate cyst" = endometrioma. CA-125 may be modestly raised in endometriosis (a classic trap vs ovarian cancer).
8. Complications
- Cervical ca: ureteric obstruction → hydronephrosis/uraemia (commonest cause of death), vesico-/recto-vaginal fistula, lymphoedema, haemorrhage.
- Endometrial ca: anaemia from bleeding, myometrial/cervical invasion, peritoneal spread (esp. serous), distant metastasis.
- Treatment-related: cervical stenosis/incompetence post-conisation; radiation cystitis/proctitis.
- Endometriosis: infertility, adhesions, bowel/ureteric involvement, malignant transformation.
9. Key differentials
- Post-coital bleeding → cervical carcinoma, cervical polyp, cervicitis, ectropion.
- Postmenopausal bleeding → endometrial carcinoma/hyperplasia, atrophic vaginitis, polyps, exogenous oestrogen.
- Koilocytes on smear → HPV (LSIL) vs reactive/atrophic changes.
- Pelvic mass + dysmenorrhoea → endometrioma vs ovarian neoplasm vs adenomyosis vs fibroid.
- p53-mutant high-grade uterine tumour → serous (Type II) endometrial vs carcinosarcoma (MMMT).
Recently asked / exam angle
- E6 binds p53, E7 binds RB — asked repeatedly; expect "match the oncoprotein to its tumour-suppressor target" or "E7 inactivates which protein?" (RB → releases E2F).
- HPV 16 → squamous, 18 → adenocarcinoma; 6 & 11 → condyloma/warts (low risk).
- Transformation zone = origin of cervical carcinoma; site to sample on Pap.
- Koilocyte image → identify HPV.
- Schiller test: dysplastic glycogen-poor epithelium does NOT take up Lugol's iodine (Schiller positive).
- Confirmatory test for cervical lesion = colposcopy-directed biopsy (not Pap).
- Endometrial Type I = endometrioid, oestrogen-driven, PTEN; Type II = serous, p53, aggressive, psammoma bodies — direct comparison MCQs.
- Tamoxifen and granulosa cell tumour as causes of endometrial hyperplasia/cancer.
- Postmenopausal bleeding → TVS endometrial thickness cut-off (>4–5 mm) → biopsy.
- Chocolate cyst / endometrioma and Sampson's retrograde menstruation theory.
- p16 immunostain as surrogate for HR-HPV transforming infection.
Rapid revision
- Transformation zone of cervix is where HPV infects and carcinoma arises.
- E6 degrades p53; E7 inactivates RB — the two defining HPV oncoproteins.
- HPV 16 → squamous cell, 18 → adenocarcinoma; 6/11 → genital warts.
- Viral integration (loss of E2 → ↑E6/E7) is the molecular switch to malignancy; p16 marks it.
- Koilocyte (perinuclear halo, raisinoid nucleus) = morphological hallmark of HPV; peaks in LSIL/CIN 1.
- CIN graded by thickness: 1 = lower 1/3, 2 = 2/3, 3/CIS = full thickness; LSIL=CIN1, HSIL=CIN2–3.
- Colposcopy-directed biopsy is confirmatory; cisplatin-based chemoradiation for locally advanced cervical ca.
- Cervical cancer is clinically staged; commonest cause of death is uraemia from ureteric obstruction.
- HPV vaccine is prophylactic — give before sexual debut (9–14 yrs).
- Type I endometrial ca: endometrioid, oestrogen-driven, obese/diabetic, PTEN, good prognosis; precursor = atypical hyperplasia.
- Type II endometrial ca: serous/clear cell, oestrogen-independent, thin elderly, p53, aggressive, psammoma bodies.
- Postmenopausal bleeding = endometrial cancer until excluded → TVS (>4–5 mm) → biopsy; surgical staging + TAH-BSO. Tamoxifen ↑ risk; OCP/parity protective. Ovarian endometriosis = chocolate cyst.