Meyahealth
HomeGeneticsConditionCowden syndrome
Back to Condition
Cowden syndrome
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Cowden syndrome

Cowden syndrome is a genetic disorder characterized by multiple noncancerous growths called hamartomas and a significantly elevated risk of developing breast, thyroid, and endometrial cancers. It is part of a spectrum of disorders caused by mutations in tumor suppressor genes, most notably PTEN.

Overview

Cowden syndrome is a genetic disorder characterized by multiple noncancerous, tumor-like growths called hamartomas and an increased risk of developing certain cancers. Almost everyone with Cowden syndrome develops hamartomas, which are most commonly found on the skin and mucous membranes (such as the lining of the mouth and nose), but can also occur in the intestines and other parts of the body. These growths typically become apparent by a person's late twenties.

Some individuals do not meet the strict criteria for a clinical diagnosis of Cowden syndrome but exhibit some of its characteristic features, particularly the associated cancers. These cases are referred to as Cowden-like syndrome, which is caused by mutations in the same genes.

The features of Cowden syndrome overlap significantly with Bannayan-Riley-Ruvalcaba syndrome, another disorder characterized by hamartomas. Because of these similarities, researchers suggest that both conditions represent a spectrum of overlapping features known as PTEN hamartoma tumor syndrome.

Symptoms & Clinical Features

In addition to noncancerous hamartomas, individuals with Cowden syndrome face unique health risks and physical characteristics:

  • An increased risk of developing cancers of the breast, thyroid, and the lining of the uterus (endometrium).
  • An increased risk of other cancers, including kidney cancer, colorectal cancer, and an aggressive skin cancer called melanoma.
  • An earlier age of cancer onset, often beginning in a person's thirties or forties, and an increased likelihood of developing multiple cancers over a lifetime.
  • An enlarged head (macrocephaly).
  • A rare, noncancerous brain tumor called Lhermitte-Duclos disease.
  • In a small percentage of cases, delayed development, intellectual disability, or autism spectrum disorder.

Frequency

While the exact prevalence of Cowden syndrome is unknown, researchers estimate that it affects approximately 1 in 200,000 people.

Causes

Cowden syndrome and Cowden-like syndrome are most commonly caused by changes in the PTEN, KLLN, or WWP1 genes:

  • PTEN gene: Mutations in this gene cause about 25 percent of Cowden syndrome cases and a small percentage of Cowden-like syndrome cases. The PTEN protein is a tumor suppressor that normally prevents cells from growing and dividing too rapidly. Mutations impair this regulatory function, leading to uncontrolled cell division and tumor formation.
  • KLLN gene: Rare cases of Cowden syndrome and Cowden-like syndrome are associated with changes in the KLLN gene, which provides instructions for making a tumor suppressor protein called killin. Reduced production of killin allows abnormal cells to survive and proliferate, leading to tumors.
  • WWP1 gene: A small percentage of cases are linked to "gain-of-function" variants in the WWP1 gene. The WWP1 protein normally binds to and impairs the PTEN protein. The altered WWP1 protein binds excessively to PTEN, blocking its tumor-suppressing activity and allowing unchecked cell proliferation.

Mutations in a few other genes account for a very small percentage of cases, while in the remaining cases, the genetic cause is unknown.

Associated Genes

  • AKT1
  • KLLN
  • PIK3CA
  • PTEN
  • SDHB
  • SDHC
  • SDHD
  • SEC23B
  • WWP1

Inheritance

Cowden syndrome and Cowden-like syndrome are inherited in an autosomal dominant pattern, meaning one copy of the altered gene in each cell is sufficient to cause the condition and increase cancer risk.

In some cases, an affected person inherits the mutation from an affected parent. Other cases result from new mutations in people with no family history of the disorder.

Other Names for This Condition

  • CD
  • Cowden disease
  • Cowden's disease
  • Cowden's syndrome
  • CS
  • MHAM
  • Multiple hamartoma syndrome

Frequently Asked Questions

Cowden syndrome is inherited in an autosomal dominant pattern, meaning only one copy of the altered PTEN gene (or other associated genes) is needed to cause the condition. If a parent has Cowden syndrome, each child has a 50% chance of inheriting the mutation. Genetic testing for PTEN mutations is available and is often used to confirm a diagnosis and for family planning or cascade screening of relatives.
The hamartomas themselves are usually benign and often do not require specific treatment unless they cause symptoms like discomfort, bleeding, or cosmetic concerns. In such cases, they can be surgically removed or treated with other local therapies. The primary focus of management in Cowden syndrome is on regular surveillance for the development of cancers, rather than routine treatment of the hamartomas themselves.
Early signs often include the development of multiple noncancerous growths (hamartomas) on the skin and mucous membranes, such as small flesh-colored bumps on the face, mouth, or hands, typically appearing by the late twenties. Other potential indicators include an abnormally large head size (macrocephaly), benign thyroid nodules, or a family history of Cowden syndrome or related cancers like breast, thyroid, or endometrial cancer at an early age.
Individuals with Cowden syndrome require a comprehensive, lifelong cancer surveillance plan that typically includes annual physical exams, dermatological evaluations for melanoma, and thyroid ultrasounds. Women should have annual mammograms and breast MRIs starting at a younger age (often 30-35), along with regular gynecological exams and endometrial cancer screening. Men should also undergo regular breast cancer screening. Kidney cancer screening with renal ultrasounds or MRIs is also recommended.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

Meyahealth

Ⓒ 2026. All rights reserved by MEYA

About UsTerms & PolicyFAQ