This page was reviewed under our medical and editorial policy by
Eric Fowler, MS, LCGC, Manager, Clinical Genetics, Western Region & Licensed Certified Genetic Counselor
This page was reviewed on November 15, 2021.
Cowden syndrome (CS), also known as Cowden’s disease and multiple hamartoma syndrome, is a rare inherited disorder that causes benign, or noncancerous, growths in various places on the body. The growths, called hamartomas, typically start to appear when patients reach their late 20s. However, they may appear at any time between birth and your mid-40s.
The growths are most likely to develop on the outer sheath of hair follicles and in the mouth. Hamartomas also may be found along the inner lining of the gastrointestinal tract.
While some tumors are benign, this syndrome increases the risk of developing certain types of cancer, including:
Women with CS are at greatest risk of developing breast cancer. The risk may be as high as 85 percent, according to the American Society of Clinical Oncology (ASCO). Women with CS may develop breast cancer at a younger age compared with other women. Women also are at risk of developing cancer in a second breast if they have cancer in the other. Men with CS are at some risk for developing breast cancer as well.
According to ASCO, other risks for people with CS include:
People with CS also may be at risk for other cancers, but more research is needed to determine whether the risks are increased.
People with CS may have:
Other signs and symptoms of CS include:
Cowden syndrome is a genetic disorder, meaning that it’s caused by a gene mutation. Most often, the mutation occurs in the PTEN (phosphatase and tensin homolog) gene that regulates cell growth. When mutated, PTEN is unable to suppress tumor growth, which increases risks for benign and cancerous tumors.
Cowden syndrome is an autosomal dominantly inherited condition, meaning the inheritance of a single gene mutation causes the condition. There is a 50 percent chance that each child of someone with CS will inherit the condition, according to the Genetic and Rare Diseases Information Center.
In rare instances, CS may result from mutations in other genes, including:
Some people may have CS and not know which gene, if any, caused it. Some may develop CS because of a new mutation that was not inherited from a parent, but that can be passed down to their children.
Men and women inherit this disorder in equal numbers. Although rare, CS is estimated to affect one in every 200,000 people, according to ASCO.
Cowden syndrome may be difficult to diagnose. It is typically detected based on a combination of factors, including physical exams or imaging studies such as CT or MRI. Cowden syndrome can also be diagnosed based on genetic test results.
The criteria are divided into three groups:
The major criteria include:
The minor criteria include:
The number of major and minor criteria patients exhibit determines a diagnosis. For example, adult patients who have two or more major criteria, one major and three or more minor criteria, or four or more minor criteria are likely to be diagnosed with CS.
Because Cowden syndrome greatly increases the risk of developing different cancers, cancer screening for early detection is important.
It’s recommended women with CS undergo:
Some women may opt to have prophylactic surgery (removing healthy organs) to reduce the risk of developing cancer of the breast and/or uterus.
Men and women with Cowden syndrome in the family should have:
Children in families with Cowden syndrome should have:
Not much may be done to control skin lesions that are common in Cowden syndrome. Some doctors prescribe topical treatments, though these haven’t been shown to provide much improvement. Some patients have seen improvements with systemic retinoids.
Facial lesions may be treated with:
Surgery to remove the benign tumors is possible, but it must be done with care because scarring may occur, and the lesions may return.
Because people with CS are at increased risk for melanoma, it’s important to take preventive measures, such as wearing sunscreen and protective clothing, when in the sun starting as a child. It’s also critical to avoid blistering burns, especially before age 20.
Clinical trials are underway to look at new treatments, including Sirolimus (rapamycin), a type of immunosuppressant and antibiotic.
Cancer screenings and follow-ups are key for those with CS. Patients should look for providers who specialize inCowden syndrome and can help sort out the challenges and options for detecting cancer early.