Juvenile polyposis syndrome is a rare autosomal dominant syndrome characterized 
by multiple distinct juvenile polyps in the gastrointestinal tract and an 
increased risk of colorectal cancer. The cumulative life-time risk of colorectal 
cancer is 39% and the relative risk is 34. Juvenile polyps have a distinctive 
histology characterized by an abundance of edematous lamina propria with 
inflammatory cells and cystically dilated glands lined by cuboidal to columnar 
epithelium with reactive changes. Clinically, juvenile polyposis syndrome is 
defined by the presence of 5 or more juvenile polyps in the colorectum, juvenile 
polyps throughout the gastrointestinal tract or any number of juvenile polyps 
and a positive family history of juvenile polyposis. In about 50%-60% of 
patients diagnosed with juvenile polyposis syndrome a germline mutation in the 
SMAD4 or BMPR1A gene is found. Both genes play a role in the BMP/TGF-beta 
signalling pathway. It has been suggested that cancer in juvenile polyposis may 
develop through the so-called "landscaper mechanism" where an abnormal stromal 
environment leads to neoplastic transformation of the adjacent epithelium and in 
the end invasive carcinoma. Recognition of this rare disorder is important for 
patients and their families with regard to treatment, follow-up and screening of 
at risk individuals. Each clinician confronted with the diagnosis of a juvenile 
polyp should therefore consider the possibility of juvenile polyposis syndrome. 
In addition, juvenile polyposis syndrome provides a unique model to study 
colorectal cancer pathogenesis in general and gives insight in the molecular 
genetic basis of cancer. This review discusses clinical manifestations, 
genetics, pathogenesis and management of juvenile polyposis syndrome.