Tumors of the Small Bowel
Tumors of the small bowel are rare. They are usually single, but may be multiple particularly in certain syndromes (i.e. intestinal polyposis syndrome). Tumors can be benign or malignant. Some benign tumors can progress and become malignant (i.e. adenomas, leiomyomas).
Most small intestine tumors are clinically silent for long periods; nearly half of all benign small intestine tumors are found only incidentally either during an operation or an investigation to visualize the intestine for other reasons. Symptoms can be chronic and/or intermittent and include abdominal pain, nausea, weight loss and bleeding. The larger the tumor, the more likely the patient will experience symptoms of bowel obstruction. Tumors can also become ulcerated and bleed.
Adenocarcinoma – Adenocarcinoma of the small intestine probably develops mainly from adenomas. Most tumors occur at the ampulla in the duodenum. Other risk factors for adenocarcinoma include Crohn's disease, celiac sprue, different types of previous surgery (i.e. surgery joining the urinary system with the intestines), and neurofibromatosis. Patients can present with obstruction or bleeding. The tumor may be diagnosed by radiologic techniques (barium studies), endoscopy or surgery, and confirmed by biopsy sampling. Treatment depends on the location, size and shape of the tumor, and whether it has spread. Options include endoscopic removal and surgery. Chemotherapy and radiation may be helpful.
Intestinal Lymphoma – Intestinal lymphoma of the small intestine is a recognized complication of celiac sprue, and can occur in immunodeficiency syndromes. Symptoms include crampy-like abdominal pain, weight loss, features of malabsorption, bleeding, or even bowel obstruction.
Leiomyosarcoma – This is a malignant tumor arising from the muscle wall of the intestine and can also arise from a benign leiomyoma. Treatment should involve complete surgical resection, wherever possible. Chemotherapy and radiation are also used.
Metastic Malignancy from Other Organs – (i.e. lung, breast or melanoma)
Leiomyoma – Leiomyomas are tumors of one of the muscle layers of the bowel wall. Some can grow into the lumen of the bowel and become ulcerated and cause bleeding or anemia, which is the most common symptom and finding. They can be very difficult to diagnose, especially when they occur in the small intestine. Endoscopic ultrasound is a useful way to determine the site of the tumor within the bowel wall. Some leiomyomas do have malignant potential. Biopsy sampling and surgical resection are usually advised.
Adenomas – Adenomas are benign tumors that do have malignant potential. They cause symptoms due to blockage. When they arise in the region of the papilla or the area of the duodenum where the bile duct and pancreas drain they can cause jaundice. Because of the risk of malignant degeneration, adenomas are usually removed (by surgery or endoscopy).
Lipomas – Lipomas are collections of fatty tissue within the wall of the intestine. They are characterized by a soft yellowish appearance when viewed endoscopically. These are completely benign tumors with no malignant potential. Lipomas do not need to be removed unless they become very large and cause obstructive symptoms (or bleeding due to ulceration).
Hemangiomas – Hemangiomas are collections of blood vessels that form a benign vascular tumor in the wall of the stomach or intestine. They are benign and sometimes found in conjunction with other syndromes (i.e. Turners syndrome, Tuberous sclerosis, blue-rubber-bleb syndrome and Osler-Weber-Rendu syndrome). Hemangiomas can cause gastrointestinal bleeding and anemia. They are detected by endoscopy. They can be treated endoscopically with application of a heater probe to burn the vessels. Patients may need resection of areas of intestine heavily involved with hemangiomas if they cause significant bleeding. Various medicinal therapies (i.e. estrogens) have been tried to reduce the amount of bleeding from hemangiomas. Reports of success have been variable.
Neurogenic Tumors – Neurogenic tumors are benign growths arising from neural (nerve) tissue. The most common variety is neurofibroma. They are usually solitary. When multiple and found diffusely in the intestine they are more likely to be associated with neurofibromatosis. The diagnosis can be confirmed by their microscopic appearance after biopsy sampling.
Polyposis Syndromes Involving the Small Bowel
There are four important polyposis syndromes that involve the small intestine: Familial Adenomatous Polyposis; Peutz-Jeghers Syndrome; Generalized Juvenile Polyposis; and, Cronkhite-Canada Syndrome. These are a group of disorders characterized by the presence of multiple polyps affecting all or parts of the gastrointestinal tract. They are distinguished by the way they can be inherited but also by the microscopic appearance of the polyps.
Familial Adenomatous Polyposis – Familial Adenomatous Polyposis are very strongly inherited (autosomal dominant). They are characterized by the presence of multiple adenomatous polyps in the colon and thus place the patient in a high risk of developing colon cancer. Over 80% of patients with these syndromes can also have adenomas involving the small intestine, which are also pre-malignant. They tend to be most common in the upper part of the small intestine (duodenum) in the region of the ampulla of Vater. In patients who have had their colon removed to avoid death from colon cancer, the most common cause of death from cancer is the development of cancer in the duodenum (the periampullary region). Unfortunately, it is not possible to remove all of the adenomas in the small intestine. Therefore, surgical or endoscopic removal is used only for large polyps, particularly in the periampullary region. Certain medications related to aspirin appear to halt or at least reduce the growth of some of these adenomas in the small intestine. Patients are usually advised to have examinations of the small intestine every few years.
Peutz-Jeghers Syndrome – This is a polyposis syndrome characterized by hamartomas (essentially excessive growth of normal tissue from the intestine). They occur especially in the jejunum and ileum, and most often present problems with bleeding and obstruction of the bowel. There is a small risk of cancer, but far less than familial adenomatous polyposis. There is also a slightly increased incidence malignancy in the gynecological organs. Peutz-Jeghers Syndrome is notable for pigmentation (dark spots) in the region of the lips and mouth. Sometimes the limbs and genital areas can be affected though this pigmentation tends to fade after puberty.
Generalized Juvenile Polyposis – Generalized juvenile polyposis can be inherited or sporadic. The polyps may be found anywhere in the intestinal tract and are characterized by their microscopic appearance. Large polyps may present with symptoms of obstruction or bleeding and there is a small increased risk of developing gastrointestinal cancer.
Cronkhite-Canada Syndrome – This is a syndrome characterized by many intestinal polyps, pigmentation, diarrhea, protein loss from the intestine and alopecia (local hair loss). The polyps are most commonly found in the small intestine and usually do not become malignant. The patient's main problem is usually malnutrition. Aggressive nutritional support is usually necessary.