LSIL and HSIL: the difference and what happens next
LSIL and HSIL differ by one letter and, in meaning, fundamentally: the first usually resolves on its own, the second is treated to prevent cancer. Neither is a diagnosis, and neither is cancer. Here is what each abbreviation stands for, how they relate to CIN 1–3, and what follows in each case.
In short: one letter, all the difference
Both abbreviations end in SIL — squamous intraepithelial lesion. What differs is the first letter, the grade:
| LSIL — low-grade | HSIL — high-grade | |
|---|---|---|
| What it is | the picture of an active HPV infection | established changes in the cells |
| Usually on histology | CIN 1 | CIN 2 or CIN 3 |
| Resolves on its own | often, especially under 30 — within a year or two | rarely |
| What is done | colposcopy or follow-up, depending on age and HPV | colposcopy with biopsy, then usually treatment |
| Is it cancer? | no | no; "precancer" is the right word, "cancer" is not |
And the key point for both: cytology does not make a diagnosis. It sorts results by how much attention they need. The diagnosis comes from a piece of tissue taken at colposcopy.
LSIL: the body usually clears it
LSIL is generally not a disease of the cervix but its reaction to an active human papillomavirus infection. The cells are mildly and superficially changed.
In women under 30, such changes resolve on their own in most cases within a year or two, as the immune system clears the virus. That is why younger patients are often offered follow-up rather than treatment: a repeat cytology or an HPV test after a set interval. After 30, LSIL is taken more seriously — at that age the virus more often turns out to be persistent.
What exactly is recommended depends on three things: age, the HPV test result, and what earlier reports showed. Hence the rule: bring all your previous results, not only the latest one.
HSIL: the case where treatment prevents cancer
HSIL means deep, established changes. They rarely resolve by themselves, and treating them is exactly what screening exists for: this is cervical cancer that does not happen.
With HSIL, colposcopy is not postponed. The cervix is examined under magnification with solutions applied, and a targeted biopsy is taken from the suspicious area itself. How the procedure goes is in the article on colposcopy.
And about the biggest fear straight away: HSIL is not cancer. Between CIN 3 and cancer there is a line the changes have not crossed, and usually years of time. So panic is unnecessary — an appointment is not.
ASC-H is not the same as ASC-US
Sometimes a report says ASC-H: "atypical squamous cells, cannot exclude HSIL". This is not a milder ASC-US but the opposite — a category that behaves like HSIL: colposcopy is needed.
The commonest and most ambiguous result, ASC-US, is covered separately in the article on ASC-US, and the normal result in the article on NILM.
SIL and CIN: two languages for one thing
These are confused more than anything else. They are not different diseases but words from different tests:
- LSIL and HSIL belong to cytology: how cells collected with a brush look. That is screening;
- CIN 1, CIN 2, CIN 3 belong to histology: how far the changes reach through the thickness of the epithelium in a tissue sample. That is a diagnosis.
They correspond, but not strictly: LSIL usually turns out to be CIN 1, HSIL to be CIN 2 or CIN 3. Histology sometimes shows less than the cytology suggested — one of the reasons treatment is decided after the biopsy rather than straight from the cytology report.
How high-grade changes are treated
If the biopsy confirms CIN 2 or CIN 3, treatment in Poland is usually a conization or a loop excision (LEEP, LLETZ): a cone-shaped piece of the cervix containing the altered cells is removed. It is an outpatient procedure, takes minutes, and is most often done under local anesthetic.
Two questions come up every time:
- Can I get pregnant afterwards? Yes. Pregnancy after conization is possible; tell the doctor managing the pregnancy about the procedure so the cervix is watched more closely;
- Is that the end of it? No. Follow-up after treatment is essential — cytology and HPV testing on schedule. The virus can remain, and the point of follow-up is to catch any return of the changes in time.
If you are pregnant
Colposcopy is performed during pregnancy too — it is safe. A biopsy is taken only when clearly needed, and treatment for CIN 2–3 is almost always deferred until after delivery: the task during pregnancy is to be sure there is no invasive process, not to remove the changes immediately.
How much time there is
Without treatment it usually takes 10–15 years from the first altered cells to cancer. So neither LSIL nor HSIL calls for action "this very evening", but neither can be put off for six months: the difference between these two results is precisely how close you are to the beginning or the end of that path.
I perform colposcopy myself, under a PTGiP skills certificate and the state certification of colposcopists of the cervical cancer prevention programme. Appointments in Warsaw at ul. Głębocka 9, held in Polish, Russian and Ukrainian; no referral or NFZ insurance needed. Bring your cytology report, your HPV result and any earlier reports.
Short answers
What does LSIL mean on a Pap test?
A low-grade squamous intraepithelial lesion — most often the picture of an active HPV infection. On histology it usually corresponds to CIN 1. In women under 30 such changes resolve on their own in most cases within a year or two.
What does HSIL mean, and is it cancer?
A high-grade lesion: established changes in the cells, usually corresponding to CIN 2 or CIN 3 on histology. It is not cancer. "Precancer" is the right word: between CIN 3 and cancer there is a line the changes have not crossed, and usually years of time.
How is LSIL different from HSIL?
In the grade of the changes and in what follows. LSIL often resolves on its own, especially under 30, and follow-up is frequently enough. HSIL rarely resolves, calls for colposcopy with a biopsy, and usually for treatment — conization or loop excision.
Is LSIL the same as CIN 1?
Usually, but they cannot be equated. LSIL is a cytology result; CIN 1 is a histology result after colposcopy. A biopsy sometimes shows less or more than the cytology suggested, which is exactly why treatment follows the histology.
Can you get pregnant after treatment for HSIL?
Yes. Pregnancy after conization or loop excision is possible. Tell the doctor managing the pregnancy about the procedure so that the cervix can be monitored more closely.
Sources
The primary sources this text rests on. Links open in a new tab.
- HPV and Pap Test Results: Next Steps after an Abnormal Cervical Cancer Screening TestNational Cancer Institute, USA — what low-grade and high-grade changes mean and what follows
- ASCCP 2019 Risk-Based Management Consensus GuidelinesASCCP — the rules for choosing between follow-up, colposcopy and treatment
- Profilaktyka raka szyjki macicypacjent.gov.pl — the Polish programme: who is eligible and what it covers
- Rekomendacje Polskiego Towarzystwa Ginekologów i PołożnikówPTGiP — the standard of care in Poland; my colposcopy certificate is issued under the same rules
This text describes the general picture and does not replace a consultation. Timings and indications differ from woman to woman and are decided at the appointment, from your history and test results.
