Tubular Adenoma of the Large Intestine: Understanding Your Pathology Report

by Jason Wasserman MD PhD FRCPC
August 16, 2026

A tubular adenoma is a precancerous polyp that develops on the inner lining of the large intestine, including the colon and rectum. It is the most common type of polyp found during a colonoscopy. Tubular adenomas are not cancer, but they can slowly change into a type of cancer called adenocarcinoma if they are left in place. For this reason, they are removed when they are found.

Tubular adenomas can develop anywhere in the large intestine, from the beginning of the colon to the end of the rectum, and your report will name the location the polyp came from. This article explains the findings you may see in a pathology report after a tubular adenoma has been removed, what each one means, and why they matter for your follow-up.

Is a tubular adenoma cancer?

No. A tubular adenoma is a precancerous polyp, not cancer. The cells inside it are abnormal, but they remain confined to the surface lining of the bowel and have not grown into the deeper tissue underneath. Growth into the deeper tissue, called invasion, is what separates a precancerous polyp from cancer.

Precancerous means that the polyp could turn into cancer over a long period of time if it were not removed. Most tubular adenomas never reach that point, and removing the polyp during colonoscopy interrupts the process entirely.

What causes a tubular adenoma?

Tubular adenomas develop when cells in the lining of the colon or rectum acquire mutations, which are errors in their DNA that allow them to grow in an abnormal, disorganized way. The earliest of these changes usually affects a tumor suppressor gene called APC, which normally acts as a brake on cell division. When that brake is lost, the cells lining the bowel begin to pile up and form a polyp. In most people, these errors build up gradually over decades and are not inherited from a parent.

Factors that increase the chance of developing a tubular adenoma include:

Increasing age. Adenomas become steadily more common after age 45, which is why screening colonoscopy is offered from that age for people at average risk.
A personal or family history of colon polyps or colorectal cancer.
Inherited conditions that cause many polyps to form, such as familial adenomatous polyposis (FAP) and Lynch syndrome. These conditions account for only a small minority of adenomas.
Long-standing inflammatory bowel disease, including ulcerative colitis and Crohn’s disease.
Lifestyle factors, including smoking, heavy alcohol use, excess body weight, physical inactivity, and a diet high in red and processed meat and low in fiber.

Finding a single tubular adenoma is common and does not by itself suggest an inherited condition.

What are the symptoms of a tubular adenoma?

Most tubular adenomas cause no symptoms at all and are found by chance during a screening colonoscopy. Larger polyps sometimes cause blood in the stool, rectal bleeding, or a change in bowel habits such as constipation or diarrhea. Bleeding may also be invisible to the eye, and stool-based screening tests are designed to detect this kind of hidden bleeding.

Because these symptoms can be caused by many different conditions, they cannot tell you whether a polyp is present. Only examination of the bowel and microscopic examination of any tissue removed can do that.

How is the diagnosis made?

Doctors diagnose a tubular adenoma only after removing the polyp and examining it under a microscope. Doctors usually remove the polyp during a colonoscopy using a procedure called polypectomy, in which a wire loop or a pair of biopsy forceps is passed through the scope to remove the growth. Endoscopic mucosal resection may remove larger or flatter polyps by lifting and removing a wider area of the lining in one piece.

The tissue is then sent to a pathology laboratory, where a pathologist examines it under a microscope. In a tubular adenoma, the glandular cells that line the bowel are arranged in closely packed, tube-shaped glands, and the cells lining those glands look abnormal, with darker and more crowded nuclei than the surrounding normal colonic mucosa. These abnormal changes are called dysplasia, and by definition, every adenoma shows dysplasia. The pathologist also confirms that the abnormal cells have not grown into the tissue beneath the lining, which would change the diagnosis to cancer.

Because a tubular adenoma is not cancer, no imaging scans are needed after the diagnosis.

Growth pattern

Adenomas of the colon and rectum are divided into three types based on the shape of the glands the pathologist sees under the microscope. Tube-shaped glands are described as tubular, and long, finger-shaped projections are described as villous. Most adenomas contain some of both, so the diagnosis depends on the proportion of villous growth:

Tubular adenoma. Less than 25% villous growth. This is the most common type and carries the lowest risk of progressing to cancer.
Tubulovillous adenoma. Between 25% and 75% villous growth.
Villous adenoma. More than 75% villous growth. This is the least common type and carries the highest risk.

A small amount of villous growth in an otherwise tubular polyp is normal and does not change the diagnosis. If your report describes a tubulovillous or villous adenoma rather than a tubular adenoma, the polyp falls into a higher risk group, and your doctor will usually recommend a shorter interval before the next colonoscopy.

Dysplasia

Every tubular adenoma shows dysplasia, a word pathologists use for cells that look abnormal under the microscope but are not yet cancer. The report will describe the dysplasia as one of two grades, and this grade is one of the findings that most influences your follow-up plan.

Low grade dysplasia. The cells look mildly abnormal. Their nuclei are darker and more crowded than normal, but the glands keep their usual orderly arrangement. This is by far the most common finding in a tubular adenoma, and the risk of cancer developing in a small polyp of this kind is very low.
High grade dysplasia. The cells look markedly abnormal, with large, irregular nuclei, and the glands lose their orderly arrangement and begin to crowd together. High grade dysplasia is still not cancer, but it sits closer to cancer along the same pathway, so complete removal and earlier follow-up are important.

Grading dysplasia involves judgment, and two pathologists will not always assign the same grade to a borderline polyp. In difficult cases, a second pathologist may review the slides before finalizing the report.

Size and number of polyps

Two other findings recorded after a tubular adenoma is removed are the polyp’s size and the total number of polyps found. Both influence how soon the next colonoscopy is recommended.

Size is usually reported in millimeters, and the threshold that matters most is 10 mm, roughly the width of a fingernail. Polyps 10 mm or larger fall into a higher-risk group. You may notice that the size in the pathology report differs slightly from the size your endoscopist described, because the polyp is measured both during the procedure and again in the laboratory, and tissue changes shape once it is removed and preserved.

The total number of adenomas removed also matters. Finding one or two small tubular adenomas is common and low risk. Finding three or more, and particularly finding ten or more, places you in a higher risk group and may prompt your doctor to consider testing for an inherited polyp condition.

Margins

The margin is the cut edge of the tissue removed during the polypectomy. The pathologist examines it to determine whether the whole tubular adenoma was removed. Your report will describe the margin in one of three ways:

Negative (clear) margin. No abnormal cells are seen at the cut edge. The polyp appears to have been removed completely.
Positive margin. Abnormal cells reach the cut edge, so some polyp tissue may remain in the bowel. Your doctor may arrange a repeat examination of that area.
Cannot be assessed. Larger polyps are often removed in several pieces, and the edges of the tissue are frequently sealed with heat during removal, leaving a cautery artifact. Either situation can make the margin impossible to evaluate reliably, and this is a common and expected finding rather than a sign that something went wrong.

A positive or unassessable margin matters more for a large polyp or one with high grade dysplasia than for a small polyp with low grade dysplasia, where the small amount of tissue left behind is usually destroyed by the removal itself.

Advanced adenoma

Some reports, or the discussion you have with your doctor afterward, will use the term advanced adenoma. This is not a separate diagnosis but a risk category that gathers together the findings described above. A tubular adenoma is called an advanced adenoma if it has any one of the following features:

A size of 10 mm or larger.
High grade dysplasia.
A villous component, meaning the polyp is a tubulovillous or villous adenoma.

An advanced adenoma carries a higher chance of progressing to cancer and a higher chance that other polyps will develop later, so it leads to a shorter interval before the next colonoscopy. A tubular adenoma smaller than 10 mm with low grade dysplasia is not an advanced adenoma, and this is the most common result by a wide margin.

What is the risk that a tubular adenoma will become cancer?

Most tubular adenomas never become cancer. The change from adenoma to colorectal adenocarcinoma is slow, typically taking a decade or more, and only a small proportion of adenomas complete it. The risk is lowest for a small polyp with low grade dysplasia and rises with increasing size, high grade dysplasia, and villous growth.

This slow timeline is what makes colonoscopy effective. Removing adenomas before they progress substantially lowers the risk of developing colorectal cancer, which is why doctors remove polyps when they find them rather than watch them.

Two related terms sometimes appear on reports and can be confusing. Intramucosal carcinoma means abnormal cells have moved into the lamina propria, a thin supporting layer just below the surface lining, but no further. In the colon, this does not behave like invasive cancer and is generally cured by removing the polyp. A malignant polyp is different: it means cancer has grown through into the deeper layer of the bowel wall and can potentially spread. If either term appears on your report, the polyp is no longer a simple tubular adenoma and your doctor will discuss what it means for you.

What happens after this diagnosis?

For a tubular adenoma, removing the polyp during the colonoscopy is the full treatment. No surgery, chemotherapy, or radiation is involved. Next, your doctor sets a follow-up interval based on your report findings, age, overall health, and family history.

Current guidelines from the US Multi-Society Task Force on Colorectal Cancer group findings roughly as follows:

One or two tubular adenomas, each smaller than 10 mm, with low grade dysplasia. The next colonoscopy is generally considered at 7 to 10 years. The 2020 guidelines lengthened this interval, so it may be longer than what you or a family member were told in the past.
Three or four tubular adenomas, each smaller than 10 mm. Generally 3 to 5 years.
An advanced adenoma, or five to ten adenomas in total. Generally 3 years.
More than ten adenomas. Generally within 1 year, along with consideration of testing for an inherited polyp condition.
A polyp removed in pieces, or with a positive margin. A repeat examination of that specific area is often arranged within 6 months, separately from the routine schedule above.

These intervals are a starting point rather than a rule, and the quality of the examination itself matters. If the bowel preparation was poor or the colonoscopy could not be completed, your doctor may recommend repeating it sooner regardless of what the polyp showed.

Your pathology report is one of several things your doctor weighs when setting that plan, and what happens after your pathology report describes the wider process. Having one adenoma removed does not mean more will form, but it does place you at somewhat higher risk than someone who has never had one, which is why ongoing surveillance is recommended rather than a return to routine screening.

Questions to ask your doctor

What type of adenoma was found, and where in the colon or rectum was it?
Did my report describe low grade or high grade dysplasia?
How large was the polyp, and how many polyps were removed in total?
Was my polyp classified as an advanced adenoma?
Was the polyp removed in one piece or in fragments?
What did the margin show, and does it mean any tissue was left behind?
When should I have my next colonoscopy, and why that interval?
Was the bowel preparation good enough for a complete examination?
Does this finding change my overall risk of colorectal cancer?
Should my children, siblings, or parents start screening earlier than usual?
Is there anything in my history that suggests I should be tested for an inherited polyp condition?
Are there changes to my diet, weight, alcohol use, or smoking that would lower my risk of new polyps?