Low Grade Squamous Dysplasia of the Esophagus: Understanding Your Pathology Report

By Jason Wasserman MD PhD FRCPC
July 29, 2026

Low grade squamous dysplasia of the esophagus is a precancerous change in the cells lining the esophagus, the muscular tube that carries food and liquid from the mouth to the stomach. The inner surface of the esophagus is covered by squamous epithelium, a layered sheet of flat protective cells. New cells are produced at the bottom of this layer and mature steadily as they move toward the surface, where they are eventually shed.

In squamous dysplasia, that orderly process breaks down. The squamous cells look abnormal and fail to mature properly as they rise through the layer. The words “low grade” mean the abnormality is mild and confined to the lower part of the layer, with the cells nearer the surface still maturing normally.

Low grade squamous dysplasia is not cancer, and it is not a tumor. It is called precancerous because, if the injury that caused it continues, it can progress over years to high grade squamous dysplasia and eventually to squamous cell carcinoma of the esophagus. For most people, this does not happen, and low grade dysplasia can also stay unchanged for years or go away entirely. This article will help you understand the findings in your pathology report, what each term means, and why it matters for your care.

What causes low grade squamous dysplasia of the esophagus?

Low grade squamous dysplasia of the esophagus develops after years of repeated injury to the squamous lining of the esophagus. It shares its causes with squamous cell carcinoma of the esophagus, the cancer it can eventually lead to, and these are different from the causes of Barrett esophagus and the gland-forming cancers that arise from it.

The two most important causes are tobacco use and heavy alcohol consumption. Each damages the lining on its own, and together they raise the risk far more than either alone, because alcohol makes the lining more permeable to the cancer-causing chemicals in tobacco smoke. Other contributors include:

Very hot beverages — Drinking tea, coffee, or maté at high temperatures over many years repeatedly scalds the lining.
Diet low in fruits and vegetables — Associated with higher risk in every population studied.
Poor oral health — One of the stronger associations in recent studies.
Achalasia — A condition in which the esophagus does not empty properly, so its contents sit against the lining.
Scarring from a caustic injury — Such as after swallowing lye or another corrosive substance, often decades earlier.
Previous radiation therapy to the chest or neck.
A previous squamous cell carcinoma of the mouth, throat, or voice box — The same exposures affect the whole lining of the upper airway and digestive tract, so abnormal areas can appear in more than one place.
Tylosis — A rare inherited condition causing thickened skin on the palms and soles, along with a substantially increased risk of esophageal squamous cell carcinoma.

Chronic acid reflux is not a cause of squamous dysplasia. Reflux injures the lower esophagus in a different way, producing reflux esophagitis and, over time, Barrett esophagus, which is a change to gland-forming cells rather than to squamous cells. Reflux is relevant here for a different reason: the inflammation it causes can make squamous cells look abnormal in ways that closely resemble dysplasia. This is discussed further in the grading section below.

What are the symptoms of low grade squamous dysplasia of the esophagus?

Low grade squamous dysplasia of the esophagus causes no symptoms of its own. The change is microscopic, involves only the thin surface lining, and does not narrow the esophagus, bleed, or cause pain.

Almost everyone with this diagnosis learns of it after an upper endoscopy performed for some other reason: investigation of swallowing difficulty or other symptoms, follow-up of a previous head or neck cancer, or screening in a person with several risk factors. When symptoms are present, they come from whatever prompted the endoscopy rather than from the dysplasia. Because the condition is silent, how a person feels is not a way to judge whether it is stable or progressing, which is why repeat endoscopy is used instead.

How is the diagnosis made?

Low grade squamous dysplasia of the esophagus is diagnosed only after a tissue sample from the esophagus is examined under a microscope by a pathologist. The sample is obtained during an upper endoscopy, in which a thin flexible tube with a camera is passed through the mouth into the esophagus, and a small tissue sample called a biopsy is taken from any area that looks abnormal.

Squamous dysplasia can be very difficult to see, because the affected lining often looks nearly normal. To find it, the endoscopist may spray the esophagus with Lugol’s iodine, a brown dye that stains healthy squamous cells because they are rich in glycogen, a stored sugar. Dysplastic cells contain little glycogen and so remain pale, appearing as unstained patches against a brown background. Special light settings that enhance the surface blood vessels are used for the same purpose. Biopsies are then taken from these areas.

Under the microscope, the pathologist assesses whether the squamous cells are maturing normally as they move from the bottom of the layer toward the surface. In low grade squamous dysplasia, the cells in the lower part of the layer have enlarged nuclei, the compartments holding the cell’s genetic material, which appear darker than normal and vary in size and shape. The cells are crowded and disorganized, and dividing cells, called mitotic figures, are seen higher in the layer than they should be. Crucially, these changes are limited to roughly the lower half of the epithelium, and the cells above still flatten and mature normally. That preserved surface maturation is what separates low grade from high grade dysplasia. No special stains or additional tests are needed to make this diagnosis; it is made on the appearance of the tissue alone.

Grading of squamous dysplasia

Squamous dysplasia of the esophagus is graded by how far the abnormal cells extend upward through the layered squamous lining. The current system used in most pathology reports has two levels:

Low grade squamous dysplasia — Abnormal cells occupy roughly the lower half of the epithelium. Cells nearer the surface still mature and flatten normally. This is the diagnosis described in this article.
High grade squamous dysplasia — Abnormal cells extend into the upper half of the epithelium, and normal surface maturation is lost. When abnormal cells replace the full thickness of the lining, the change may also be called squamous cell carcinoma in situ.

Your report may use other wording for the same finding. Some pathologists use the term intraepithelial neoplasia, so low grade squamous dysplasia may appear as low grade squamous intraepithelial neoplasia. Older reports, and some centers still, use a three-level system of mild, moderate, and severe dysplasia. Mild dysplasia corresponds to low grade. Severe dysplasia corresponds to high grade. Moderate dysplasia sits between the two, and how it is assigned differs between systems, so if your report uses that word it is worth asking your doctor which category it was placed in and what follow-up applies.

Two cautions apply to this diagnosis. First, grading squamous dysplasia is one of the more subjective judgments in pathology, and pathologists looking at the same slide do not always agree, particularly at the boundary between reactive change and low grade dysplasia. Second, inflammation, an erosion, or healing after any injury causes the squamous cells to multiply rapidly and look abnormal, a pattern called reactive changes, which can closely resemble low grade dysplasia. For these reasons, a diagnosis of squamous dysplasia is often reviewed by a second pathologist, and biopsies are sometimes repeated after inflammation has been treated. A diagnosis that is revised on review is not an error; it reflects a genuinely difficult distinction being resolved with more information.

What is the risk that low grade squamous dysplasia will become cancer?

Low grade squamous dysplasia of the esophagus carries a small increased risk of progressing to squamous cell carcinoma of the esophagus, but for most people that progression never occurs. Three outcomes are all possible: the dysplasia can regress and disappear, it can remain unchanged for many years, or it can advance to a higher grade.

The most reliable long-term figures come from large screening programs in northern China, where this cancer is common. In those studies, people with mild or low grade squamous dysplasia developed esophageal squamous cell carcinoma at a rate of roughly 0.2% per year, with a cumulative risk of about 1% to 2% over eight years. This is roughly three times the risk faced by someone with a normal esophageal lining, but it still means that the large majority of people never develop cancer. Higher grades carry substantially higher risk: cumulative incidence rises to roughly 4% to 5% for moderate dysplasia and 15% or more for severe dysplasia and carcinoma in situ. Studies from Western countries, where the diagnosis is made much less often and usually in people already under investigation for something else, have reported higher rates, which likely reflects who gets biopsied rather than a different biology.

Findings and circumstances that raise the risk of progression include:

Continued smoking and drinking — The strongest modifiable factor by a wide margin.
A larger or more extensive abnormal area — Particularly a large unstained area on Lugol’s iodine staining.
Dysplasia found at more than one site — Suggesting the whole lining has been affected.
A previous squamous cell carcinoma of the head, neck, or esophagus.
Older age and male sex — Both associated with higher progression rates in screening studies.

Because the abnormal cells are confined to the surface lining, dysplasia found and treated at this stage cannot have spread anywhere, which is why finding it is regarded as an opportunity rather than a setback.

What happens after this diagnosis?

After low grade squamous dysplasia of the esophagus is diagnosed, two things generally run in parallel: reducing the exposures that caused the change, and monitoring the lining over time so that any progression is caught early.

Reducing exposure is the part with the largest effect. Stopping smoking and reducing or stopping alcohol substantially lower the chance that dysplasia will advance, and they also lower the risk of a second cancer elsewhere in the mouth, throat, or voice box. Support for both is available through the care team, and letting cooling time pass before drinking hot beverages is also commonly discussed. These changes matter more here than in most precancerous conditions, because the injury driving the change is ongoing and can be removed.

For monitoring, repeat endoscopy with biopsies is the usual approach, typically at intervals of one to two years for low grade dysplasia, with the exact interval depending on the size of the abnormal area, other risk factors, and whether the diagnosis was confirmed on review. Endoscopic screening programs have shown that surveillance in this group meaningfully lowers the chance of dying of esophageal cancer, because lesions are found when they are still confined to the lining.

Treatment of the abnormal lining itself is not usually undertaken for low grade dysplasia, since the risk of progression is lower than the risks of the procedure. That calculation changes if the grade advances. For high grade dysplasia, endoscopic treatments such as endoscopic resection, radiofrequency ablation, or cryotherapy are used to remove or destroy the abnormal lining before cancer develops. Where a diagnosis is uncertain or the abnormal area is extensive, referral to a center with particular expertise in early esophageal disease is common.

Questions to ask your doctor

How confident is the diagnosis of low grade squamous dysplasia, and was it reviewed by a second pathologist?
Could inflammation or a healing injury explain the changes seen in my biopsy?
Did my report use the words mild, moderate, or severe dysplasia, and how does that map onto low and high grade?
How large was the abnormal area, and was it found in more than one place?
Was Lugol’s iodine or another dye used during my endoscopy to look for abnormal areas?
Based on my report and risk factors, what is my estimated risk of progression?
How often should I have repeat endoscopy and biopsies?
Should the biopsies be repeated sooner to confirm the diagnosis?
Is any treatment of the abnormal lining appropriate now, or is monitoring the better option?
What help is available to stop smoking and reduce alcohol, and how much difference would that make for me?
Should I also be examined for abnormal areas in my mouth, throat, or voice box?
What symptoms should prompt me to contact you before my next scheduled endoscopy?