Malignant

Benign

Classification

Diagnosis

Clinical Presentation

Bleeding. Lower intestinal bleeding is the hallmark presentation of most polypoid conditions. The bleeding is frequently associated with crampy abdominal pain. The blood is usually red, indicating its origin in the lower gastrointestinal tract and small in quantity, unlike bleeding from duplications or Meckel's diverticula with peptic ulceration. If the bleeding is from polyps in the small bowel, the blood will appear darker. In the rare cases of duodenal or gastric polyps, rectal bleeding may appear black (i.e., melena).

Pain. Crampy abdominal pain is a frequent symptom along with bleeding. The pain does not necessarily occur with the bleeding.

Intussusception. Traction on a polyp may cause intussusception anywhere it occurs. However, jejuna or ileal polyps as a cause of intussusception are quite rare, especially for the most common form of intussusception, the ileocolonic type. Colocolonic intussusception may occur when a colonic polyp serves as a lead point. The symptoms include crampy, intermittent pain, bleeding from venous engorgement of the mucosa and signs of intestinal obstruction (i.e., vomiting, distension and obstipation). Unlike idiopathic intussusception, intussusception from a polyp occurs in older children and may not be reduced by contrast enema.

The diagnosis of polypoid lesions depends primarily on two modalities: intestinal contrast studies and endoscopy. Endoscopy is advantageous as it can be both diagnostic and therapeutic. Endoscopy is also excellent for studying the colon, stomach and duodenum. It is clearly more limited when the polyps are small bowel in origin. Contrast studies for colonic polyps can be very accurate and can be useful to follow polyps for changes in number and size. Upper intestinal polyps in the stomach and duodenum are also accurately visualized with contrast studies.

Small bowel polyps may be difficult to image even with small bowel enemas. Small bowel polyps are notoriously difficult to diagnose and thankfully, occur only very rarely. Diagnosis is most often made at the time of laparotomy when bleeding or obstructive symptoms have prompted an operation.

Isolated Juvenile Polyps.

These are the most common polypoid lesions of infancy and childhood. The peak age of incidence is between 3 and 10 years. As with most polyps, crampy abdominal pain and bleeding with bowel movements are the presenting symptoms. Juvenile polyps are hamartomatous excrescences of the intestinal mucosa. They appear to lengthen from traction caused by peristalsis and the flow of intestinal contents. There is no malignant potential, and juvenile polyps naturally autoamputate if given enough time. 75% of juvenile polyps occur in the rectum and sigmoid colon, but juvenile polyps may occur in the right colon as well. A full colonoscopy has been advocated by some when a child presents with symptoms as up to 50% of children may have additional polyps identified in the right and/or transverse colon.

Peutz-Jeghers Syndrome.

This well-known syndrome causes multiple polyps predominantly in the jejunum and duodenum. The genetic defect has been isolated to the LKB1 gene on chromosome 19 and has an autosomal dominant pattern of inheritance. Its hallmark feature is the pigmented lesions observed on the buccal mucosa and lips of these patients. Malignant degeneration within the polyp can occur, especially with gastric and duodenal polyps, so lifelong surveillance is necessary. There is also an 18-fold increased risk for extra-intestinal cancers (uterine, breast and ovarian in females; testicular and head/ neck cancers in males).

Adenomatous Polyps.

This lesion is rare but known to occur in childhood. Malignant degeneration can occur as in the adult-type lesion. Familial adenomatous polyposis (FAP) is a syndrome that results in multiple colorectal polyps (see below). Traditionally, the presence of at least 100 individual polyps is required to make this diagnosis.

Hemangiomatous Polyps.

Hemangiomatous polyps cause profuse bleeding and occur predominantly in the distal small bowel. Profuse bleeding may require excision if it occurs repeatedly. Hemangiomatous polyps tend to regress with time as do most hemangiomas after the age of 2 to 5 years.

Juvenile Polyposis and Familial Adenomatous Polyposis (FAP).

Juvenile polyposis is an autosomal dominant disorder which causes polyps predominantly in the colon (often 50-200 seen at colonoscopy) and small bowel. The lesions resemble adenomatous polyps individually but are actually mucous-retention polyps. These polyps can occur anywhere along the gastrointestinal tract. It is considered a premalignant condition and as many as 50% of these children will eventually develop gastrointestinal malignancy. Serial surveillance with polypectomy is indicated with more aggressive surgical resection reserved for dysplasia or invasive cancer. Infantile juvenile polyposis occurring in children under 2 years of age is associated with multiple large polyps, rectal bleeding, protein-losing diarrhea and failure to thrive and may require a more aggressive surgical approach.

Familial adenomatous polyposis is characterized by hundreds of adenomatous polyps in the rectum and colon causing diarrhea and bleeding. FAP also represents an autosomal dominant pattern of inheritance with the genetic defect isolated to the APC tumor-suppressor gene on chromosome 5. Malignant degeneration in one or more polyps is virtually certain before the age of 20 years and proctocolectomy with restorative ileoanal reconstruction is advocated before age 15-20 (See Treatment below). Patients with FAP are also at increased risk for other neoplasms including desmoid tumors, epidermoid cysts, osteomas, hypertrophy of retinal pigment epithelium and upper gastrointestinal polyps and/or malignancy. Upper endoscopic surveillance is indicated once colon polyps have been demonstrated. Children with a family history of FAP also have an 850 times greater risk of developing hepatoblastoma.

Adenocarcinoma

Although rare, isolated colonic or small bowel adenocarcinoma can occur in childhood. It can be mistaken for a juvenile polyp until it has advanced beyond the stage where it can be excised completely. Adenocarcinomas usually arise from villous adenomas.

Lymphoma

Small bowel lymphoma is usually a non-Hodgkin's B-cell lymphoma. The two most common gastrointestinal sites of non-Hodgkin's lymphoma are the distal small bowel and the stomach. Proximal gastric lesions may be visualized and biopsied endoscopic-ally although the lesion originates in the submucosa. In the small bowel, computed tomography scanning can usually image the lesion if it has attained sufficient size to cause symptoms. Lymphoma of the bowel is rare in infancy, but the incidence increases with advancing age peaking in adolescence. Bleeding is the main symptom from gas­tric lesions. Small bowel lymphomas cause crampy abdominal pain and may result in intussusception. A few erode and perforate into the free abdominal cavity presenting as gastrointestinal perforation.