A genetic disorder leading to congenital hamartomatous polyps of the gastrointestinal tract associated with perioral melanin spots. There is an increased risk of malignancy.
Familial Hamartomatous Polyposis Syndrome; Jegher Syndrome; Hutchinson-Weber-Peutz Syndrome; Lentigo-Polypose-Digestive Syndrome.
1:50,000 to 1:200,000 live births.
Autosomal dominant with high degree of penetrance.
Mutation in the serine threonine kinase (STK11) gene on chromosome 19p13.3. STK11 is a tumor suppressor gene and expressed throughout the body. It is postulated that it enables epithelial cells of the small intestine to undergo constant replication with low rates of malignancy.
Hamartomatous muscularis mucosae polyps are present in the esophagus, stomach, small bowel, and colon. Jejunal polyps are a consistent feature. Polyps are usually multiple but not premalignant. There is, however, an increased risk for adenomas and adenocarcinomas of the gastrointestinal tract. Polyps may also be present in the nasopharynx, bronchial mucosa, bladder, and ureter. Melanin spots (also called lentigines) on the lips, buccal mucosa, and digits, and around the anus: they are dark brown to black and round to oval. They are present in infancy and childhood, but may fade with age.
Phenotype severity is based on earlier onset of gastrointestinal pathology arising from the polyps. Intussusception, colicky abdominal pain, and bleeding are the usual symptoms. The cumulative risk of developing an intestinal or extraintestinal cancer (bronchogenic carcinoma, benign or malignant thyroid disease; breast, pancreatic, or reproductive tract cancer) is up to 93% to the age of 70. Affected females are prone to develop benign ovarian tumor; testicular tumors are described in boys 4 to 6 years old with gynecomastia.
Precautions before anesthesia
Patients present for regular surveillance colonoscopy. Check hemoglobin level because anemia caused by chronic intestinal bleeding is frequent. Check renal function if there is a history of hematuria.
The presence of nasal polyps should be excluded before inserting nasal tubes or catheters.
Other conditions to be considered
Familial Adenomatous Polyposis (FAP): Genetic disorder of colon cancer that is associated with the presence of large numbers of colorectal polyps (even thousands) with significant incidence of cancer transformation. The risk of developing colon cancer with FAP is almost 100% by the age of 40 years. An autosomal dominant inheritance involving the APC gene on chromosome 5q21.
Gardner Syndrome (Intestinal Polyposis, Type III): Autosomal dominant polyposis disorder characterized by gastrointestinal adenomas, mostly colon and periampullary cancer. Other clinical features include soft-tissue lesions, such as sebaceous cysts, fibromas, leiomyomas, and lipomas, as well as bony lesions, such as multiple osteomas, exostoses, bone cortical thickening, and dental abnormalities. ...