Cowden syndrome (CS) is an autosomal dominant hereditary disorder caused by mutations in the phosphatase and tensin homolog (PTEN) gene, and it is estimated to occur at a frequency of 0.5 cases per 100000 population.1) CS is known to be associated with multiple hamartomas of the skin, mucous membranes, brain, breast, thyroid, and colon. This evidence concerns the gene PTEN and autosomal dominant disease.