Juvenile polyposis syndrome: a study of genotype, phenotype, and long-term outcome

Juvenile polyposis syndrome is phentoypically and genotypically heterogeneous. It is associated with an increased risk of GI cancers, and surveillance is recommended. Few data exist that detail the outcomes of surveillance in juvenile polyposis syndrome.

The aim of this study was to review clinical features, genetic mutations, and long-term outcome data in patients with juvenile polyposis syndrome.

This study is a retrospective review.

The Polyposis Registry, St Mark's Hospital, was used in the performance of this study.

Patients with juvenile polyposis syndrome who were followed up at our institution were included.

Forty-four patients (27 male) from 30 kindreds were included. Fifteen were diagnosed by screening, and 29 presented symptomatically. Nineteen patients had SMAD4 mutation and 9 had BMPR1A mutation. Five patients (11%) had valvular heart disease. Telangiectasia/vascular abnormalities were observed in 4 (9%) patients, and macrocephaly was observed in 5 (11%). Six patients (14%) developed cancer; 4 had cancer at the time of diagnosis of juvenile polyposis syndrome, 3 developed cancer while on surveillance (1 patient had a second primary). All patients with advanced upper GI disease had SMAD4 mutations. Where germline mutation was known, all patients with telangiectasia had SMAD4 mutation. Seven patients required GI surgery at our institution: colectomy and ileorectal anastomosis (1), restorative proctocolecotomy (1), anteroposterior excision for rectal cancer (1), gastrectomy (2), and laparotomy and intraoperative enteroscopy (1). There were no complications of endoscopic surveillance. Colonic polyps predominated; 535 of 767 (69.8%) of colonic polyps were right sided. One patient had a solitary significant small-bowel polyp. Sixty-five juvenile polyps contained dysplasia (mild to moderate). Two patients had severe dysplasia or cancer found in carpeting polyps.

This is a retrospective review. The cohort size, although modest, is good for such a rare condition.

Extraintestinal features are common. Gastrointestinal surveillance is safe. Most colonic polyps are right sided, and detecting dysplasia is uncommon. Carpeting polyps are of particular concern.