nonpolyposis syndrome (Lynch's syndrome)其大腸息肉組織型態為腺瘤(adenoma),腺瘤常發生於近端大腸(proximal colon),息肉具有癌化可能,此病症可能伴隨有子宮內膜及卵巢腫瘤(endometrial and ovarian tumors),雖然發生率較少,但是也有可能發生胃癌(gastric cancer)、泌尿生殖癌(genitourinary cancers)、胰臟癌(pancreatic cancer)、膽道癌(biliary cancer)