Cowden syndrome

Cowden syndrome is a rare 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. These growths 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 intestinal tract and other parts of the body. Abnormal growths on the skin and mucous membranes typically appear by a person's late twenties.

People with Cowden syndrome have an increased risk of developing several types of cancer, including cancers of the breast, thyroid, and the lining of the uterus (the endometrium). Noncancerous breast and thyroid diseases are also common. Other signs and symptoms of Cowden syndrome can include an enlarged head (macrocephaly); a rare, noncancerous brain tumor called Lhermitte-Duclos disease; and intellectual disability.

Researchers estimate that Cowden syndrome affects about 1 in 200,000 people; however, the exact prevalence of this condition is unknown because it can be difficult to diagnose.

Mutations in the PTEN gene cause Cowden syndrome.

PTEN is a tumor suppressor gene, which means that it normally prevents cells from growing and dividing too rapidly or in an uncontrolled way. Mutations in the PTEN gene have been identified in about 85 percent of people with Cowden syndrome. These mutations, which affect all of the body's cells, prevent the PTEN protein from effectively regulating cell survival and division. Uncontrolled cell division can lead to the formation of hamartomas and cancerous tumors.

The cause of the remaining Cowden syndrome cases is unknown. Mutations in a region of DNA that regulates the activity of the PTEN gene may be responsible for some cases of this condition.

Read more about the PTEN gene.

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to increase the risk of developing noncancerous and cancerous tumors.

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