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CION Cancer Clinics
Hundreds of polyps: what FAP actually looks like | CION Cancer Clinics
In classic FAP the lining of the large bowel carries hundreds of small polyps, usually from the teenage years. Each one starts harmless, but together they make bowel cancer very likely if nothing is done. This page explains what a colonoscopy shows, the clues FAP can leave elsewhere in the body, and how the milder attenuated form differs. At CION Cancer Clinics, our oncologists plan screening and care for families with an inherited cancer syndrome, explained in plain words.
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Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed September 2026, next review due September 2027
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On this page
- What does FAP actually look like inside the bowel?
- Where else can FAP show itself?
- How is FAP usually found?
- What do the words on a colonoscopy report mean?
- How does classic FAP differ from the milder form?
- What this page cannot tell you
- Four things families tell us, and what is actually true
- Common questions about what FAP looks like
The short answer
What does FAP actually look like inside the bowel?
In classic FAP, the lining of the large bowel is covered in small lumps called polyps, often hundreds and sometimes thousands. On a colonoscopy screen it can look as if the bowel wall has been carpeted. Most of the polyps are tiny, a few millimetres across, and each one on its own is harmless at first.
Why the number is the whole story
An ordinary adult might have one or two polyps removed during a routine check. In FAP there are far too many to remove one by one, and new ones keep appearing. Every polyp carries a small chance of turning into cancer over time. Multiply that small chance by hundreds and the overall risk becomes very high.
When the polyps appear
They usually begin in late childhood or the teenage years, and their number grows through the twenties. A child from an FAP family can look and feel perfectly well while the polyps are already forming. This is why families are checked on a schedule rather than when someone feels unwell.
What the milder form looks like
In attenuated FAP there are fewer polyps, often tens rather than hundreds. They tend to appear later and sit more on the right side of the bowel. It is still the same gene and still needs regular checks.
You will not see these polyps from the outside. They are found by colonoscopy.Across the body
Where else can FAP show itself?
The APC fault is in every cell, so some signs appear well away from the bowel. Some are harmless clues. Others need their own checks.
The large bowel
Many small polyps spread along the lining, usually from the teenage years. This is where the main cancer risk sits, and it is managed with colonoscopy and planned surgery.
The stomach and duodenum
Most people with FAP also have polyps in the upper gut. Many stomach polyps are harmless. Polyps in the duodenum are watched for life with a separate camera test.
Skin, bone and teeth
Some families notice signs a dentist or skin doctor may spot first.
Clues that can appear
- Soft lumps under the skin, called epidermoid cysts
- Hard bony lumps on the jaw or skull
- Extra teeth, or teeth that never come through
- Firm growths in the belly wall, called desmoids
The back of the eye
Flat, dark patches on the retina are seen in many FAP families. They do no harm to sight. An eye doctor may notice them during a routine eye check.
Not sure whether this applies to you?
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How is FAP usually found?
A reason to look
Either a relative already has FAP, or a young person has symptoms such as bleeding from the back passage, loose stools or tiredness from a low haemoglobin.
The colonoscopy
A thin camera looks along the whole large bowel. The doctor sees how many polyps there are and where they sit, and removes or samples some of them.
The biopsy report
A pathologist confirms the polyps are adenomas, the type seen in FAP, and says how abnormal the cells look.
The gene test
A blood test looks for the APC fault. Once it is found, every relative can be tested for that exact fault.
On your report
What do the words on a colonoscopy report mean?
- Polyposis
- Many polyps in the bowel at once. It describes what the doctor saw, before any gene test.
- Adenoma
- The type of polyp in FAP. It can slowly turn into cancer if it is left in place for years.
- Innumerable or carpeting
- Too many polyps to count. Doctors use these words for classic FAP.
- Dysplasia
- How abnormal the cells look. Low grade is milder. High grade is closer to cancer and is acted on sooner.
- Desmoid tumour
- A firm growth of fibrous tissue, often in the belly. It does not spread to other organs, but it can press on nearby structures.
- CHRPE
- Short for the flat, dark patches at the back of the eye. They are a harmless clue to FAP in some families.
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Side by side
How does classic FAP differ from the milder form?
Classic FAP
Attenuated FAP
Hundreds to thousands of polyps
Usually tens of polyps
Polyps start in late childhood or the teens
Polyps tend to appear later in adult life
Spread through the whole large bowel
Often more on the right side of the bowel
Preventive surgery is almost always needed
Some people are managed with colonoscopy alone for years
Being straight with you
What this page cannot tell you
It cannot tell you whether the polyps in your own report mean FAP. A polyp count, a biopsy and a family history are read together by a bowel specialist, and a gene test is usually needed to be sure. What your specific variant means is a question for the counsellor who ordered the test.
It cannot show you pictures
Photos from other people's colonoscopies are easy to find online and are often frightening. They show one moment in one person. Your own endoscopist can show you your images and explain what they mean for your plan.
Who this does not apply to
Most adults who have one or a few polyps removed at a routine check do not have FAP and do not need a gene test. Polyps become common with age. If nobody in the family had many polyps or bowel cancer young, this page is very unlikely to be about you.
Counselling in Telugu can be arranged, so the whole family can follow the explanation.Commonly believed
Four things families tell us, and what is actually true
"There is no blood in the stool, so there cannot be many polyps."
Most polyps cause no symptoms at all. A young person can have hundreds and feel completely well. Bleeding, when it comes, is often a late sign.
"Every one of those polyps is a cancer."
Almost none of them are cancer when first found. They are growths with the potential to change over years. The concern is the sheer number, which makes it very likely that one will change if nothing is done.
"The doctor can simply remove all the polyps during the colonoscopy."
In classic FAP there are too many to remove, and new ones keep forming. That is why preventive surgery on the bowel is planned at the right time in life.
"The lumps on the jaw or skin must be cancer as well."
Bony lumps, skin cysts and the eye patches are harmless in themselves. They matter because they can be a clue that the family carries FAP.
Questions we are asked
Common questions about what FAP looks like
How many polyps does it take to call it FAP?
Classic FAP is usually described when a person has a hundred or more adenomas. Fewer polyps can still be FAP, especially the attenuated form. The count is one clue among several, and a gene test normally settles the question.
Can FAP be seen on a CT scan or ultrasound?
Not reliably. The polyps are small and lie on the inner lining of the bowel. A colonoscopy is the test that shows them and lets the doctor take samples. Scans are used for other questions, such as looking for desmoid tumours.
Will my child look different if they have FAP?
Almost always not. Children with FAP look and grow like any other child. A few may have skin cysts or small bony lumps, but most have no outward sign. That is why testing in the family matters more than looking for clues.
What symptoms should make us ask about FAP?
Bleeding from the back passage, loose stools that do not settle, or unexplained tiredness in a young person deserve a check. They are far more often due to something common. In a family with FAP they should never be dismissed.
Do the dark spots in the eye affect vision?
No. They are flat patches of extra pigment and do not affect sight. They do not need treatment. They are useful only as a clue, and many people with FAP do not have them at all.
Are the extra teeth a problem?
They can crowd other teeth or stop teeth coming through, and a dentist may need to remove them. If your dentist finds extra or buried teeth and there is bowel disease in the family, tell them. It helps join up the picture.
Does attenuated FAP look normal on colonoscopy?
It can look much like ordinary polyps, which is why it is sometimes missed. A higher than usual polyp count in a younger adult, or a family pattern of polyps, is often what prompts the gene test.
What should we bring to the first appointment?
Bring any colonoscopy reports, biopsy reports and photos you were given, and a list of relatives who had polyps or bowel cancer, with their ages. Call the CION helpline if you are not sure who to see first.
Your Specialists
Meet CION's oncologists. Bring your family history or genetic report to them.
Our medical oncologists see people with a strong family history of cancer, arrange genetic counselling and testing where it fits, and plan the checks that follow.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
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Sources
- GeneReviews (NCBI) — APC-Associated Polyposis Conditions
- MedlinePlus Genetics — Familial adenomatous polyposis
- National Cancer Institute — Genetics of Colorectal Cancer (PDQ) - Health Professional Version
- MedlinePlus Genetics — APC gene
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Familial adenomatous polyposis explainedThe condition itself, start to finishAttenuated FAP: a milder courseIf your polyp count was lower than classic FAPGardner syndrome featuresThe bone, skin and desmoid signs in more detailWhen screening should start in an FAP familyWhen children and relatives are first checked
Talk to us
Was your colonoscopy report full of polyps?
Share the report and your family history with us. We will help you reach a bowel specialist and a genetic counsellor who can explain what it means. One helpline serves every CION centre.