Introduction and classification

Gastrointestinal (GI) polyps usually present in children with rectal bleeding, or abdominal pain with intussusception in the case of small bowel polyposis. Other children are asymptomatic and come to endoscopy as part of a screening or surveillance program for a familial inherited polyposis syndrome.

Gastrointestinal polyps fall into two main categories: hamartomas or adenomas (Table 42.1). The endoscopic management and the role of GI surveillance of each condition are summarized in Table 42.2. Solitary polyps in children are most commonly hamartomas, predominantly of the juvenile type, and such polyps are benign. Once removed, repeat colonoscopy is not required unless rectal bleeding reoccurs.

Familial adenomatous polyposis

Familial adenomatous polyposis (FAP) is an autosomal dominant inherited condition caused by a gene mutation in the adenomatous polyposis coli gene (APC). Thirty percent of cases of FAP are de novo mutations and will be identified at colonoscopy after assessment for rectal bleeding or at an older age, presenting with colorectal cancer. Many mutations have been identified and correlations have been reported between gene mutation locus and clinical manifestations. Mutations clustered around codon 1250–1464 are associated with a more severe phenotype of FAP, whereas mutations at either extreme end of the gene are associated with a more attenuated appearance and later presentation. Patients may manifest extracolonic features at presentation including bony lesions, such as osteomas, exostosis, supernumerary teeth, or desmoid tumors, congenital hypertrophy of the retinal pigment epithelium, and tumors of the brain or hepatoblastoma.

Genetic screening for at‐risk children with an affected parent is usually performed at age 12–14 years if the family‐specific gene mutation is known. This genetic testing or colonoscopy should be performed earlier if there are symptoms consistent with colonic polyposis such as rectal bleeding or mucus passage. Pancolonoscopy should be performed in those children predicted to be affected by FAP confirmed at gene testing. The endoscopist should concentrate in the rectum, identifying adenomas >2 mm in size (measured with biopsy forceps), and then inspect the rest of the colon to identify and quantify size and number of adenomas. If no adenomas are visualized, then there is value in using dye spray to identify microadenomas to confirm the phenotype of FAP. Once adenomas have been found, there is no value in routine polypectomy. Instead, the colonoscopy should be repeated every 1–3 years depending on the polyp burden until the adolescent is referred for colectomy.

Colectomy is key to preventing colorectal cancer (CRC) which is ubiquitous in these patients by age 20–50 depending on polyp burden. Patients should be referred for colectomy depending on the appearance of the colon. Those with >500 adenomas, or adenomas measuring >1 cm, should undergo colectomy sooner rather than delay (Figure 42.1). Those with fewer adenomas can undergo repeat colonoscopy every 1–3 years and be referred at a time that suits the social and educational path of the adolescent. Families should be registered with a regional or national polyposis registry so they are recalled for their colonoscopies.

Colectomy will either be by subtotal with an ileorectal anastomosis (IRA) or restorative proctocolectomy with ileal pouch anal anastomosis (IPAA). The choice of procedure will be directed by the surgeon taking into account the colonic and rectal polyp burden, genotype, and risk of desmoid disease. Post colectomy by IRA, the rectal remnant must be inspected six monthly by flexible sigmoidoscopy to identify and remove any adenomas >5 mm that develop to prevent subsequent rectal cancer. Those would undergo an IPAA and also require annual endoscopic assessment of the pouch

Although upper GI pathology occurs in patients with FAP including gastric adenomas, benign polyps, and duodenal ampullary dysplasia, routine gastroscopy is rarely required until over the age of 20 years. Duodenal disease develops in later years, requiring side‐viewing gastroscopy after the age of 25 years.

There is no role for chemoprevention medication to delay or avoid colectomy in patients with FAP.

Juvenile polyposis syndrome

Juvenile polyposis syndrome (JPS) is an autosomal dominant heritable predisposition for colorectal and gastric polyps. The majority of affected individuals harbor mutations in the SMAD4 gene on chromosome 18q21 or BMPR1A gene on chromosome 10q23.2. The syndrome is defined by the presence of multiple (>5) juvenile polyps in the colon, juvenile polyps in the stomach or any juvenile polyps in the context of a positive family history of JPS. Individuals harboring SMAD4 mutation may, in general, exhibit a more aggressive disease phenotype along with overlap with arteriovenous malformations in hereditary hemorrhagic telangiectasia (HHT).

Colonoscopic screening usually starts by age 12–14 years in at‐risk individuals identified by family history, with or without mutation. The goal is to identify juvenile polyps and establish the diagnosis based on the parameters above. Surveillance colonoscopy is repeated annually until polyp free, then repeated every 1–5 years, dependent on polyp burden and recurrent symptoms. The goal is to remove polyps with larger lesions submitted for histological changes including atypia and limiting polyp burden that may correlate with bleeding and obstruction risk.

The logistic preparation for these procedures is critical. Colonoscopy in JPS frequently entails multiple, including right‐sided, polypectomy. Whenever possible, these procedures should be performed by an experienced team, under general anesthesia, with good or excellent preoperative preparation. Provision should be made for the broadest range of hemostatic techniques and devices (including endo‐clips) to be available. Postoperative bleeding, although uncommon, and perforation resulting in peritonitis are significantly more likely than in routine, nontherapeutic procedures; patients and families need to be counseled to watch for symptoms or signs of adverse outcomes with a clear plan of action to address any concerns.

Relatively large (>2 cm) colonic polyps are characteristic of JPS and can be taken out safely (Figure 42.2). Some polyps are multilobular or clustered onto a common stalk. The technique for polypectomy in these instances should include snaring toward the upper quarter of the stalk. Allow best positioning of the polyp ahead of cautery in order to eliminate (or maximize) the opportunity for arc occurrence, and leave redundant stalk to be clipped in the case of excessive bleeding post polypectomy. Sometimes, larger or clustered polyps without easy access to the stalk require piecemeal polypectomy. Whenever possible, polyps or fragments of polyps removed during these procedures should be recovered and submitted for histology, although the risk of reintubation of the colon post polypectomy is presumed to be higher and needs to be factored against the loss of histopathological sampling.

Juvenile polyposis of infancy (JPI) reflects a significantly more severe phenotype of juvenile polyposis that has been associated with contiguous deletions of the BMPR1A and PTEN genes. Given the rarity of this syndrome, management guidelines are unclear but regular, close, multivisceral surveillance, including upper and lower endoscopy from an early age, appears justified.