Receiving an abnormal result from a Pap test can be worrying. Many people search for information about the diagnosis, which is often Low-grade Squamous Intraepithelial Lesion (LSIL). This finding is a common result from routine cervical screening and is not a diagnosis of cancer. Understanding what LSIL means and its relationship to a common viral infection, along with the recommended follow-up steps, can reduce anxiety and empower you in your care.
Understanding the LSIL Diagnosis
LSIL stands for Low-grade Squamous Intraepithelial Lesion, a finding made during a Pap test (cervical cytology screening). This term describes mild, abnormal changes found in the surface cells of the cervix when examined under a microscope. The diagnosis classifies cellular appearance rather than being a disease itself.
The “low-grade” designation signifies that the cellular changes are slight and typically involve only the most superficial layers of the cervical lining. These mild abnormalities are often referred to as mild dysplasia. LSIL is the most frequently reported abnormal Pap test result, especially in younger individuals.
LSIL changes are not cancer, but they are considered pre-cancerous, meaning they could potentially progress to higher-grade lesions if unmonitored. However, the body’s immune system frequently resolves these mild changes without medical intervention. An LSIL diagnosis serves as an early warning sign, prompting closer surveillance instead of immediate aggressive treatment.
The Direct Link Between LSIL and Human Papillomavirus
LSIL is almost always the result of an active infection with the Human Papillomavirus (HPV). This connection is so strong that an LSIL diagnosis reflects the visible cellular changes caused by the virus. Studies show that 75% to 90% of individuals diagnosed with LSIL will also test positive for HPV.
HPV infection causes cervical cells to grow and divide abnormally, resulting in the characteristic mild changes seen as LSIL. HPV is a common sexually transmitted infection, and most sexually active people contract it at some point. The body’s immune system typically clears the virus naturally, often before it causes noticeable cellular changes.
HPV types are divided into low-risk and high-risk groups. High-risk types, particularly HPV 16 and 18, are responsible for most cervical cancers, but LSIL can be caused by either group. The presence of LSIL indicates the virus is actively replicating in the cervical cells.
While LSIL is strongly associated with HPV, a small percentage (3% to 10%) may receive an LSIL result but test negative for high-risk HPV. This discrepancy occurs because the test may not detect all strains or the LSIL could be related to inflammation. For the average person, a positive LSIL result indicates an active, usually temporary, HPV infection.
Medical Management and Follow-Up After an LSIL Result
The standard medical response to an LSIL diagnosis is active surveillance, or “watchful waiting.” This approach is recommended because the immune system is highly likely to clear the HPV infection, allowing the cellular changes to regress spontaneously. The specific management plan is tailored based on the patient’s age and whether an HPV test was performed with the Pap test.
For younger patients, particularly those aged 21 to 24, repeat Pap testing is generally recommended at 12-month intervals, as spontaneous regression is highest in this group. For individuals aged 25 or older, guidelines often involve repeat testing or a referral for a colposcopy. A colposcopy is an in-office procedure where the clinician uses a magnifying device to closely examine the cervix.
If LSIL is accompanied by a positive test for high-risk HPV, guidelines often recommend a colposcopy to assess the extent of cellular changes. If the high-risk HPV test is negative, especially in women over 30, the risk of a more advanced lesion is lower, and repeat testing in 12 months is often preferred. Deferring immediate intervention prevents overtreatment, which can sometimes lead to complications in future pregnancies, since most LSIL lesions resolve naturally.
The goal of follow-up is to monitor for persistence or progression to a higher-grade abnormality, such as HSIL, which carries a greater risk of developing into cancer. The frequency of repeat testing depends on the initial results and established risk-based guidelines. Patients must follow the testing schedule prescribed by their healthcare provider to ensure persistent or progressive changes are detected early.
Prognosis and Long-Term Outlook
The long-term outlook following an LSIL diagnosis is favorable, reflecting the benign natural history of the condition. Studies indicate that 80% to 90% of LSIL lesions regress or clear completely without treatment within two years. The body’s immune system suppresses the underlying HPV infection, allowing the cervical cells to return to normal.
The risk of LSIL progressing to a high-grade lesion or invasive cancer is low. Only 7% to 10% of cases progress to a high-grade lesion requiring treatment. Progression is more likely if the HPV infection persists over a longer period, especially if it involves a high-risk HPV type.
Continued participation in screening is the best way to maintain a positive prognosis. Adhering to the follow-up schedule ensures low-grade changes are monitored, and any potential progression is caught early. The HPV vaccine, while not treating an existing infection, is recommended for eligible individuals as a preventative measure against future infections with high-risk HPV types.