High Grade Dysplasia of the Larynx: Understanding Your Pathology Report

Section Editor: Jason Wasserman MD PhD FRCPC
July 27, 2026

High grade dysplasia of the larynx is a precancerous change in the lining of the voice box. Dysplasia means the squamous cells lining the larynx look abnormal under the microscope and are not maturing normally. “High grade” means those changes are marked and involve much of the thickness of the lining.

High grade dysplasia is not cancer. The abnormal cells remain within the epithelium, the thin surface lining, and have not grown into the tissue beneath. That downward growth is called invasion, and its absence is what separates this diagnosis from an invasive squamous cell carcinoma. What the diagnosis does indicate is a meaningful risk that cancer could develop in that area over time, which is why high grade dysplasia is usually treated rather than simply watched.

Your report may describe this same finding using other terms, and they can be confusing to see. Moderate dysplasia and severe dysplasia both fall within the high grade category in the larynx. Carcinoma in situ sits at the top of the same category and is sometimes reported separately. If your report uses any of these terms, this article applies to you.

High grade dysplasia develops most often on the vocal cords, in the part of the larynx called the glottis, and usually affects adults over the age of 40.

This article explains the findings you are likely to see on a pathology report for high grade dysplasia of the larynx, what each one means, and why it matters for your care.

What does “high grade” mean?

Pathologists sort dysplasia of the larynx into grades because the grade is the strongest predictor of whether the abnormal area will progress to cancer. Two systems are in use, and understanding how they relate explains why several different words can describe the same finding.

The system currently recommended by the World Health Organization for the larynx has two categories:

Low grade dysplasia. The changes are limited to the lower part of the lining and the cells show at most minor abnormalities.
High grade dysplasia. The cells show clearly abnormal features extending from the lower half through to the full thickness of the lining, with loss of the normal orderly maturation from base to surface.

Some laboratories still use an older three-tier system of mild, moderate, and severe dysplasia. When the two are lined up, mild dysplasia corresponds to low grade, while both moderate and severe dysplasia fall within high grade. This information is important to consider, as a report indicates that moderate dysplasia of the larynx is typically treated as a high-grade change rather than an intermediate one. The two categories were combined because evidence demonstrates that moderate and severe dysplasia pose a similar risk of progressing to cancer, which is significantly higher than that associated with mild dysplasia.

Squamous cell carcinoma in situ describes the most marked end of this range, where the abnormal cells involve the entire thickness of the lining. The word “carcinoma” understandably causes alarm, but carcinoma in situ means the cells are still confined to the surface and have not invaded. It is not an invasive cancer.

One further point is worth knowing, because patients sometimes seek second opinions and find the grade has changed. Grading dysplasia is a judgment rather than a measurement, and agreement between pathologists is only moderate. A change in grade on review is common and does not mean an error was made.

What causes high grade dysplasia of the larynx?

High grade dysplasia of the larynx develops when the squamous cells lining the voice box are damaged repeatedly over many years. Each round of injury and repair leaves small errors in the cells’ genetic material, and once enough accumulate, the cells stop maturing normally. The main causes are:

Tobacco. By far the most important cause.
Alcohol. Heavy use raises risk on its own, and combining it with smoking raises risk considerably more than either alone.
Previous radiation to the neck. Radiation given years earlier for another condition can lead to changes in the treated area.
A weakened immune system. This includes long-term immune suppression after an organ transplant.

Because the whole lining of the larynx has usually been exposed to the same irritants, a new abnormal area can develop elsewhere in the voice box even after the first has been treated. This is one of the main reasons follow-up continues over the long term.

What are the symptoms of high grade dysplasia of the larynx?

Because high grade dysplasia usually develops on the vocal cords, the most common symptom is a change in the voice, since even a small abnormal area interferes with the way a vocal cord vibrates. Symptoms include:

Hoarseness or a change in the voice, often the only symptom
A rough, strained, or breathy voice quality
Throat discomfort or a feeling of something in the throat
Difficulty swallowing, which is less common
Noisy breathing or shortness of breath, only when a larger area is involved

Any change in the voice lasting more than two to three weeks should be assessed by an ear, nose, and throat specialist. Hoarseness appearing early is genuinely helpful here, because it often brings the change to attention while it is still confined to the surface.

How is the diagnosis made?

High grade dysplasia is diagnosed only when tissue from the abnormal area is examined under the microscope by a pathologist. A specialist may see a white or thickened patch on the vocal cord when examining the larynx, but the appearance alone cannot establish the diagnosis or the grade.

The tissue is obtained by biopsy during a procedure called microlaryngoscopy, in which a thin scope is passed through the mouth under general anesthetic so the surgeon can see the vocal cords directly and remove the abnormal area or take a sample from it.

Under the microscope, the pathologist assesses how abnormal the cells look and how far up through the thickness of the lining the changes extend. Your report may note keratinization, meaning the cells are producing keratin, a tough protein normal in skin but not in the lining of the larynx, or hyperkeratosis, a thickened keratin layer on the surface that is often what makes the area look white. Most importantly, the pathologist confirms that the abnormal cells have not broken through the base of the lining into the tissue beneath.

One limitation of a small biopsy is worth knowing. It samples only part of the abnormal area, and the region sampled is not always the most abnormal one. This is a reason the whole area is often removed rather than just sampled, so it can be examined completely and an invasive cancer ruled out across the entire lesion.

Surgical margins

When the abnormal area is removed rather than only sampled, the report may describe the margins, the cut edges of the tissue removed. Margins are not usually assessed after a small biopsy, because only part of the area was taken.

Negative (clear) margin. No dysplasia at the cut edge. The abnormal area appears to have been completely removed.
Positive (involved) margin. Dysplasia reaches the cut edge, meaning some abnormal tissue may remain. Your doctor may discuss removing more tissue or monitoring the area closely.
Cannot be assessed. The tissue was fragmented, or the edges were cauterized during removal, which is common with laser procedures. This does not mean the procedure was inadequate, but it makes careful follow-up more important.

Two points are specific to the larynx. The surgeon works to remove the abnormal area while preserving as much normal vocal cord as possible, because taking too much tissue affects the voice, so margins here are often narrower than elsewhere in the body. And a clear margin means the abnormal-looking tissue was removed, not that the risk has been eliminated, since the surrounding lining may already carry damage while appearing normal. This is why surveillance continues regardless of what the margins show.

What is the risk that high grade dysplasia will turn into cancer?

High grade dysplasia of the larynx carries a meaningful risk of developing into squamous cell carcinoma, and this is the reason removal is usually recommended rather than watchful waiting. Reported rates vary widely between studies, from roughly 15% to over 40%, reflecting differences in how the lesions were classified and how long patients were followed. What is consistent is that the risk is substantially higher than for low grade dysplasia, where reported rates are generally in the range of 5 to 10%.

Two things influence what happens next. The first is whether the abnormal area was completely removed, which is what the margin result describes. The second is whether the irritation continues, since ongoing smoking keeps the process going while stopping removes the cause.

These figures are averages drawn from groups of patients followed over many years. They describe patterns rather than predictions for any one person, and your own risk is best discussed with the specialist who can see your larynx and knows your history.

What happens after the diagnosis?

For high grade dysplasia, complete removal of the abnormal area is generally recommended, most often using a laser through a scope passed into the throat and performed by an ear, nose, and throat surgeon. Removal serves two purposes: it takes out the abnormal tissue, and it allows the whole area to be examined so an unsuspected early cancer is not missed. Radiation is occasionally considered for extensive changes or for changes that keep returning after removal.

Because the condition is non-invasive, removal of lymph nodes is not needed, and chemotherapy has no role.

Two things matter alongside any procedure. The first is stopping smoking and reducing alcohol, which removes the ongoing damage driving the process. Support for quitting is a standard part of care and worth asking for. The second is regular follow-up examination of the larynx, since dysplasia can return at the same site or appear elsewhere in the voice box. Follow-up generally continues for years rather than for a fixed period. Voice therapy with a speech-language pathologist may also be offered if your voice has changed after a procedure on the vocal cords.

Questions to ask your doctor

Does my report say high grade dysplasia, moderate or severe dysplasia, or carcinoma in situ, and do they mean the same thing in my case?
Was there any sign of invasive cancer?
Where in my larynx is the abnormal area, and how much is involved?
Was the whole area removed, or was only a sample taken?
If it was removed, were the margins clear?
Do I need further treatment?
What is my risk of developing cancer?
How often will my larynx be examined, and for how long?
Will my voice be affected, and would voice therapy help?
What help is available to me for stopping smoking and reducing alcohol?
What changes should prompt me to call before my next visit?