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Cowden syndrome: what the PTEN fault means for you | CION Cancer Clinics
Cowden syndrome is a rare inherited condition caused by a fault in the PTEN gene. It causes harmless growths in the skin, mouth, gut, thyroid and breast, and it raises the risk of breast, thyroid, womb, kidney and bowel cancers. This page explains what the gene does, the signs that point to the syndrome, how it is diagnosed and what it means for your relatives. 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 is Cowden syndrome?
- Which parts of the body does Cowden syndrome affect?
- How Cowden syndrome is usually diagnosed
- The words you will meet, in plain language
- What a Cowden diagnosis means, and what it does not
- What this page cannot tell you
- Four things people assume about Cowden syndrome
- Common questions about Cowden syndrome
The short answer
What is Cowden syndrome?
Cowden syndrome is an inherited condition caused by a fault in a gene called PTEN. It causes many non-cancerous growths in the skin, mouth, gut, thyroid and breast, and it raises the risk of several cancers. It is rare, and it is often missed for years because each sign on its own looks ordinary.
What the PTEN gene normally does
PTEN works like a brake on cell growth. It tells cells when to stop dividing and when to die off. When one copy of PTEN is faulty from birth, that brake is weaker in every cell. Tissues grow in small, disorganised lumps, and over a lifetime some cells are more likely to become cancerous.
Why doctors call it a hamartoma syndrome
A hamartoma is a harmless overgrowth of the tissue that normally belongs in that place. Cowden syndrome is one of several related conditions caused by PTEN faults. Doctors group them under one name, PTEN hamartoma tumour syndrome, because the gene and the care plan are the same.
How it passes through a family
A parent with a PTEN fault has a one in two chance of passing it to each child, son or daughter alike. In some people the fault is new, and neither parent carries it.
Cowden syndrome raises risk. It does not mean cancer is certain.Four areas to know
Which parts of the body does Cowden syndrome affect?
Most of these features are harmless on their own. Together they form a pattern that a trained eye can recognise.
Skin and mouth
Small bumps on the face, gums and tongue are among the most common signs. They are often mistaken for warts or ignored completely.
Often seen
- Small skin-coloured bumps around the nose and mouth
- Pebbly bumps on the gums or tongue
- Rough spots on the palms or soles
Head size and development
Most people with a PTEN fault have a larger than average head. Some children have delayed development or autism. A rare, slow-growing brain growth called Lhermitte-Duclos disease can also occur.
Benign growths inside the body
Lumps in the thyroid and breast, fibroids in the womb, fatty lumps under the skin and polyps in the bowel are all common. Most are not cancer, but they need to be watched and checked properly.
A raised risk of some cancers
The risk is higher than in the general population for several organs. The size of the risk varies between studies.
Main cancers
- Breast cancer, the largest risk for women
- Thyroid cancer, which can start young
- Cancer of the womb lining
- Kidney, bowel and skin melanoma
Not sure whether this applies to you?
Ask an oncologistStep by step
How Cowden syndrome is usually diagnosed
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Someone notices the pattern
Often a dermatologist, a thyroid surgeon, a breast surgeon or a paediatrician links several findings that nobody had connected before.
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The features are checked against criteria
Doctors use agreed lists of major and minor features. Meeting enough of them makes the diagnosis likely, even before any test.
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A genetic counsellor takes the family history
They ask about head size, skin bumps, thyroid problems and cancers in relatives. Parents may be examined too, because signs can be subtle.
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A blood test looks for a PTEN fault
Finding a pathogenic variant, meaning a fault known to break the gene, confirms the diagnosis and lets relatives be tested for the same fault.
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A surveillance plan is written
Checks for the breast, thyroid, womb, kidney, bowel and skin are planned across the years. Each starts at a different stage of life.
On your report
The words you will meet, in plain language
- PTEN
- The gene behind Cowden syndrome. Its job is to slow cell growth, so a faulty copy lets tissues overgrow.
- Hamartoma
- A harmless lump made of the tissue normally found in that place, just grown in a disorganised way.
- PTEN hamartoma tumour syndrome
- The umbrella name for Cowden syndrome and its related conditions. Reports often shorten it to PHTS.
- Macrocephaly
- A head size larger than most people of the same age and sex. It is measured with a simple tape.
- Pathogenic variant
- A change in the gene known to stop it working. This is what people mean by a gene fault.
- Autosomal dominant
- One faulty copy is enough to cause the condition, and it can pass from either parent to a child of either sex.
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Side by side
What a Cowden diagnosis means, and what it does not
It does mean
It does not mean
A raised lifetime risk of several cancers
That cancer will definitely develop
Regular checks across several organs
Every lump found is cancer
Relatives can be tested for the same fault
Every relative carries it
Some benign lumps may need removing
Surgery is the only option on offer
Children may need thyroid and development checks
A child's future is decided by the result
Being straight with you
What this page cannot tell you
It cannot tell you whether you or your child has Cowden syndrome. The signs are common one at a time and only mean something together. A clinical geneticist or genetic counsellor needs to examine you, measure head size, look at the skin and mouth, and take a full family history before deciding whether a PTEN test makes sense.
It cannot interpret a result you already have
What your specific variant means is a question for the counsellor who ordered the test. Some PTEN variants are clearly harmful, and some are of uncertain significance. The two lead to very different plans.
Who this does not apply to
Most people with a thyroid nodule, a few skin bumps or a family member with breast cancer do not have Cowden syndrome. These findings are very common on their own. Testing is for people whose features add up to the pattern, or who have a relative with a confirmed PTEN fault.
Commonly believed
Four things people assume about Cowden syndrome
"The skin bumps are just warts, so they do not matter."
On their own they are harmless. As part of a pattern with a large head, thyroid lumps or early breast problems, they can be the first clue to an inherited condition.
"It only affects women, because it is about breast cancer."
Men carry and pass on PTEN faults exactly as women do. Men also have raised risks of thyroid, kidney, bowel and skin cancer, and need their own checks.
"A normal PTEN test means there is nothing wrong."
If your features clearly fit, doctors may still manage you as having the syndrome. A small share of people with the pattern have no fault found with current tests.
"Nothing can be done, so it is better not to know."
The gene fault cannot be corrected, but a lot can be done around it. Regular checks aim to find cancers early, when treatment is simpler, and relatives can find out where they stand.
Questions we are asked
Common questions about Cowden syndrome
How rare is Cowden syndrome?
It is rare, and it is probably under-recognised because the signs are easy to miss. No reliable Indian figures exist. Many people are diagnosed only after a cancer, or after a doctor notices several unrelated-looking features together.
Is Cowden syndrome the same as PTEN hamartoma tumour syndrome?
Cowden syndrome is the best-known condition within that group. The umbrella name also covers Bannayan-Riley-Ruvalcaba syndrome and some rarer overgrowth conditions. They share the same gene and much of the same care plan.
Which cancer is the biggest worry?
For women, breast cancer carries the largest raised risk. Thyroid cancer is the other main concern for both sexes and can occur young. Risks of cancer of the womb lining, kidney, bowel and melanoma are also raised. Figures vary between studies, so ask your counsellor what applies to you.
Can Cowden syndrome be treated?
The gene fault cannot be reversed. Care focuses on regular checks, removing lumps that cause trouble or look suspicious, and treating any cancer early. Some drugs that act on the PTEN pathway are being studied, but studies so far are small.
Should my children be tested?
Often yes, because thyroid checks and development assessments can begin in childhood. A counsellor will discuss the timing with you. Each child has a one in two chance of carrying the fault if a parent does.
Is preventive surgery recommended?
It is one option some women discuss, alongside regular breast checks. It is a personal decision made with a breast surgeon and a genetic counsellor, never a requirement. Our pages on risk-reducing surgery cover the choices in more detail.
Can Cowden syndrome affect marriage prospects?
Many families worry about this. Who to tell, and when, is a personal choice. A counsellor can help you plan that conversation and explain the options for having children without passing the fault on.
Where should we start?
Write down the features you have noticed and any cancers in the family, with ages. Take that to a genetic counsellor or your oncologist. Call the CION helpline if you are not sure whom to see, and someone will point you to the right clinic.
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) — PTEN Hamartoma Tumor Syndrome
- MedlinePlus Genetics — Cowden syndrome
- MedlinePlus Genetics — PTEN gene
- National Cancer Institute — Genetics of Breast and Gynecologic Cancers (PDQ) - Health Professional Version
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
The physical signs that lead to diagnosisPictures in words of the skin, mouth and head signsCancer risks in Cowden syndromeWhich organs carry the raised risk, and why figures varySurveillance across breast, thyroid, kidney and bowelThe checks that follow a diagnosisCowden syndrome in childrenHead size, development and thyroid checks in childhood
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