Cowden syndrome

Overview
Cowden syndrome is an inherited disorder characterized by multiple tumor-like growths called hamartomas and an increased risk of certain forms of cancer. Almost everyone with this condition has hamartomas. These small, noncancerous 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. People with Cowden syndrome have an increased risk of developing several types of cancer, including cancers of the breast, thyroid, and uterus. Indeed, women with Cowden syndrome have as much as a 25-50% lifetime risk of developing breast cancer. Noncancerous breast and thyroid diseases are also common. Other signs and symptoms of Cowden syndrome can include an enlarged head, a rare noncancerous brain tumor called Lhermitte-Duclos disease and mental retardation.

Epidemiology
Because Cowden syndrome can be difficult to diagnose, the exact prevalence is unknown; however, it probably occurs in at least 1 in 200,000 people.

Genetics
Mutations in the PTEN gene cause Cowden syndrome. PTEN is a tumor suppressor gene, which means it helps control the growth and division of cells. Inherited mutations in the PTEN gene have been found in about 80 percent of people with Cowden syndrome. These mutations prevent the PTEN protein from effectively regulating cell survival and division, which can lead to the formation of tumors. Cowden syndrome is one of several inherited diseases caused by mutations in the PTEN gene.

In the other 20 percent of Cowden syndrome cases, the cause is not yet known. Some of these cases may be caused by mutations in a region of DNA that regulates the activity of 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 cause the disorder. 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. It is characterized by numerous hamartomas, among other symptoms.