Conditions · Obstetrics and gynecology
Cervical intraepithelial neoplasia (cervical dysplasia) !
Abnormal, precancerous cells on the cervix caused by persistent HPV. It is silent, found by screening, and treating it prevents cervical cancer.
Updated 2026-11-01
Structures involved
Tap one to see what it is and open it in 3D.
In the clinical exam
Why it happens
- Oncogenic viruses and H. pylori: the table to know
- Tumour suppressor genes: RB, TP53, APC, BRCA and the two-hit hypothesis
- Cytology: the Pap test, fine-needle aspiration and body fluids
- Dysplasia and carcinoma in situ
- Multistep carcinogenesis: the adenoma–carcinoma sequence
- Precancerous conditions: when chronic inflammation, metaplasia or hyperplasia raise the risk
Show 3 more
What it is
A precancerous change of the squamous epithelium of the cervix, almost always caused by persistent infection with high-risk human papillomavirus (HPV). It is graded by how much of the epithelium is abnormal; high-grade lesions can progress to invasive cervical cancer if left untreated.
Who gets it
Cervical cancer remains one of the leading cancers in women in Colombia and Latin America, so detecting and treating precancer is a public health priority. WHO targets for 2030 include vaccinating 90% of girls against HPV by age 15, screening 70% of women with a high-performance test by 35 and again by 45, and treating 90% of women with precancer or cancer.
Causes
- Persistent infection with high-risk HPV types, mainly 16 and 18 (about 70% of cervical cancers)
- Sexual transmission of HPV, usually soon after sexual debut
- Most HPV infections clear spontaneously within one to two years
Risk factors
- Early sexual debut and multiple sexual partners
- Immunosuppression, especially HIV infection
- Smoking
- Never or infrequently screened
- Long-term use of combined oral contraceptives and high parity
- Other sexually transmitted infections (chlamydia)
- Lack of HPV vaccination
Pathophysiology
HPV infects basal cells at the transformation zone, where columnar epithelium is replaced by squamous metaplasia. When the virus integrates into the host genome, its E6 protein degrades p53 and E7 inactivates the retinoblastoma protein (Rb), freeing the cell cycle. Atypical cells first occupy the lower third of the epithelium and then its full thickness, without crossing the basement membrane; invasion marks the transition to cancer.
Classification
- CIN 1 (low-grade squamous intraepithelial lesion, LSIL): lower third of the epithelium, often regresses
- CIN 2: up to two thirds of the epithelium (high grade)
- CIN 3 / carcinoma in situ (high-grade lesion, HSIL): full thickness, without invasion
- Adenocarcinoma in situ: glandular precancer of the endocervix
- Cytology reported with the Bethesda system (ASC-US, LSIL, ASC-H, HSIL, AGC)
Symptoms and signs
- Usually no symptoms
- Found by cytology, HPV testing or visual inspection during screening
- Bleeding after intercourse or abnormal discharge suggests an associated infection or invasive cancer
Diagnosis
- Clinical
- Screening of asymptomatic women and speculum examination. In Colombia, cytology is used in younger women and high-risk HPV DNA testing from about age 30, and in remote areas visual inspection with acetic acid and Lugol's iodine (VIA/VILI) followed by immediate treatment.
- Tests
- Cervical cytology (Pap smear or liquid-based), high-risk HPV testing (it can be self-collected), and colposcopy with directed biopsy, which gives the histological diagnosis (CIN grade). Endocervical curettage when the transformation zone is not fully visible.
- Imaging
- Not used for diagnosis of CIN; colposcopy is the magnified visual examination. MRI or CT are reserved for staging if invasive cancer is found.
Differential diagnosis
- Invasive cervical cancer
- Cervicitis (chlamydia, gonorrhoea, trichomoniasis)
- Cervical ectropion
- Atrophic or reactive changes on cytology
- Cervical polyp
Goal of treatment
Remove or destroy high-grade lesions before they become invasive, avoid overtreating low-grade lesions that usually regress, preserve fertility and ensure follow-up.
Treatment
- Follow-up
- CIN 1: observation with repeat cytology or HPV testing, since most lesions regress; this approach is also used for CIN 2 in young women and during pregnancy.
- Procedure
- Excision of high-grade lesions (CIN 2–3) by loop electrosurgical excision procedure (LEEP or LLETZ) or cold-knife conisation, which also provides tissue for diagnosis.
- Procedure
- Ablation (cryotherapy or thermal ablation) when the lesion and transformation zone are fully visible and invasion is excluded; it allows a screen-and-treat approach in a single visit.
- Surgical
- Hysterectomy only in selected cases, such as recurrent high-grade disease in women who do not want more children or adenocarcinoma in situ.
- Follow-up
- Follow-up with HPV testing and cytology after treatment, because recurrence and later cancer risk remain higher than average for years.
Complications
- Progression to invasive cervical cancer if untreated or not followed up
- Recurrence after treatment
- After excision: bleeding, infection and cervical stenosis
- Cervical insufficiency, preterm birth and PPROM after deep or repeated excisions
- Anxiety and loss to follow-up
Prognosis
Excellent when detected and treated: treatment cures most high-grade lesions. CIN 1 regresses spontaneously in most women. Untreated CIN 3 has a substantial risk of becoming invasive cancer over years.
Prevention
- HPV vaccination before the start of sexual activity (included in the Colombian national immunisation programme)
- Regular screening with a high-performance test, even in vaccinated women
- Condom use, which reduces but does not eliminate HPV transmission
- Stopping smoking
Test yourself
Think of the answer, then tap the question to see it.
Which HPV proteins inactivate p53 and Rb?
E6 degrades p53 and E7 inactivates the retinoblastoma protein (Rb).
Where on the cervix does dysplasia usually begin?
In the transformation zone, where columnar epithelium undergoes squamous metaplasia.
What is the usual management of CIN 1?
Observation with repeat testing, because most low-grade lesions regress spontaneously.
Which test gives the definitive diagnosis of CIN after an abnormal screening result?
Colposcopy with directed biopsy (histology).
What obstetric risk follows a deep cervical excision?
Cervical insufficiency with a higher risk of preterm birth and preterm rupture of membranes.
Related conditions
- Human papillomavirus (HPV) infection
- Cervical cancer
- HIV infection and AIDS
- Chlamydia infection
- Preterm labour and birth
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Cervical dysplasia (MedlinePlus (U.S. National Library of Medicine), 2024); Cervical cancer (World Health Organization, 2024).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.
