Hamartomatous polyps occur in both the upper and lower gastrointestinal tract and exhibit a wide variety of shapes and sizes: Both sessile and stalked polyps occur, and their number ranges between only a few to over 100 polyps. Juvenile polyps (whereby “juvenile” refers to the histology and not the age of the patient) may develop from infancy to adulthood. Most JPS patients exhibit polyps at the age of 20. Hemorrhaging, and resulting anemia, is a potential complication.
While most juvenile polyps are benign, malignant transformations may also occur. The incidence of colorectal carcinomas is 17-22% at 35 years of age, increasing to 68% at the age of 60. The average age at colon carcinoma diagnosis is 42. The incidence of gastric carcinomas is 21% in patients with gastric polyps.
JPS/HHT syndrome can occur in patients with a SMAD4 mutation and exhibit variable manifestations of juvenile polyposis and HHT. The latter may be epistaxis, telangiectasia, arteriovenous malformations (AVS), or drumstick fingers. Clinical symptoms usually appear during early childhood, with pulmonary AVM and epistaxis almost always occurring. Complications of JPS/HHT syndrome may include anemia, migraines, and headaches.
In addition, a SMAD4 mutation may lead to thoracic aortic diseases such as aortic root dilation, aneurysms, and mitral valve dysfunctions.