NCIt definition : A hamartomatous polyp that occurs in the stomach, small and large intestines, and
rarely within the esophagus, nasopharynx and the urinary tract. The Peutz-Jeghers
polyps are grossly lobulated and dark. Microscopically, they have a central core of
smooth muscle covered by mucosa. The smooth muscle shows tree-like branching. The
question of whether or not the Peutz-Jeghers polyp is precancerous is a matter of
controversy. The loss of heterozygosity on chromosome 19p (where the responsible gene
LKB1 is located) suggests that the increased risk of malignancy may be due to malignant
transformation from hamartoma to adenocarcinoma. --2002;