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Small Bowel Neoplasms

 

 

Related narrative: Duodenal Villous Adenoma

Small bowel neoplasms are relatively rare, comprising about 5% of GI neoplasms and 1-2% of GI malignanciesS. Malignancies tend to occur a little earlier and are slightly more common in men and Polynesians. Patients with familial adenomatous polyposis (FAP) syndrome and Crohn's have an increased incidence of adenomas and carcinoma of the duodenum and small bowel. The most common benign small bowel neoplasms are leiomyomas, adenomas and lipomas. Most lesions occur in the distal small bowel, but duodenal lesions are relatively frequent per unit area.

Adenomas constitute 35% of benign lesions and may be tubular adenomas, villous adenomas, tubulovillous or Brunner's gland lesions. Brunner's gland lesions occur in the proximal duodenum, may mimic ulcer symptoms, and have no malignant potential. Twenty percent of adenomas occur in the duodenum, 30% in jejunum and 50% in the ileum. Benign lesions are usually incidental findings, while malignant lesions account for 75% of symptomatic patients. Symptoms from benign lesions are usually longstanding, vague and mild (dyspepsia, anorexia, dull pain). Occasionally obstruction from the lesion acting as the lead point for intussusception or bleeding may be the presenting symptom.

Villous adenomas are rare and are most frequently found in the duodenum. They are associated with FAP. They have the potential to progress to malignancy and may grow to large size (> 5 cm). At initial endoscopy, 54% of FAP patients have duodenal adenomas and 56% of the remaining patients have developed adenomas by the time of follow up examination. Adenomas show progression in about two thirds of individuals observed. These patients have a 97% cumulative lifetime risk of developing duodenal adenoma, and a 4% risk of duodenal carcinoma. Duodenal adenomas tend to be periampullary. Large lesions, those with villous histology and hi-grade dysplasia are at greatest risk for malignant transformation. The lesions tend to be sessile, lobulated polypoid masses. Surface erosion is typical of villous lesions. About half of ampullary villous adenomas will have foci of carcinoma at the time of diagnosis. A friable, bleeding surface is a sign of malignancy. Only about 10% of patients with ampullary carcinoma present with the classic triad of painless jaundice, anemia and painless gallbladder enlargement (Courvoisier's gallbladder).

The optimal management of duodenal adenomas is not established. Endoscopic resection is often not possible, especially for periampullary lesions. When periampullary lesions are resected endoscopically, some authors place a pancreatic stent because of the 12% incidence of pancreatitis. There is also an 8% incidence of post-resection hemorrhage. Transduodenal surgical excision has a reported 9% perioperative mortality, and there is a 25-33% recurrence rate. Whipple procedure carries a 2-10% mortality and higher rate of morbidity. Alternative therapies such as Nd/YAG laser and photodynamic ablation and argon plasma coagulation have associated complications and are not yet proven.

References:

Townsend: Sabiston Textbook of Surgery, 16th ed., WB Saunders, 2001, 897-899.

Conio, M, et al, Management of duodenal adenomas in 98 patients with familial adenomatous polyposis, Endoscopy 1999;31:412-6 Kim, MH, et al, Tumors of the major duodenal papilla, Gastrointestinal Endoscopy, Volume 54 • Number 5 • November 2001

Norton, ID et al, Safety and outcome of endoscopic snare excision of the major duodenal papilla, Gastrointestinal Endoscopy, Volume 56 • Number 2 • August 2002


This page was last modified on 1-Apr-2004.