People with Cowden syndrome develop characteristic lesions called hamartomas, which are small, noncancerous growths that are most commonly found on the skin and mucous membranes (such as the lining of the mouth, nose, and intestines), but can also occur other parts of the body, such as the thyroid and breast.
Skin abnormalities in people with Cowdens syndrome can include oral and skin papillomas and benign growths of the skin called trichilemmomas.