[Hamartomatous polyposis syndrome].

The hamartomatous polyposis syndromes, which comprise Peutz-Jeghers syndrome, juvenile polyposis, and Cowden's disease, occur less frequently. These disorders are characterized by multiple hamartomatous polyps in the gastrointestinal tract, and distinctive extraintestinal manifestations. We have recognized that these have inheritance with autosomal dominant trait by genetic studies. Most of them have high malignant potential which make transformation to neoplasms in gastrointestinal tract and extraintestinal organs. It is necessary for patients with these disorders to manage appropriately. Therefore, we must understand their natural histories and pathological characterization. Because affected patients and their first degree relatives belong to high risk groups of malignant neoplasms, we have to intensively survey them through their lifetime.