Hamartomatous muscularis mucosae polyps are
present in the esophagus, stomach, small bowel, and colon. They are usually
multiple but not premalignant. There is, however, an increased risk for
adenomas and adenocarcinomas of the gastrointestinal (GI) tract. Polyps may also be present in
the nasopharynx, bronchial mucosa, bladder, and ureter.