General Information
• Small intestinal tumors are less common than other GIS tumors.
• The most common benign tumors are adenoma and leiomyoma.
• Malignant tumors; Proximal adenocarcinoma, distal lymphoma and carcinoid tumor are most common. In general, adenocarcinomas are most common in the small intestines.
Adenocancer
• It is most commonly located in the duodenum (ampulla vateri) and proximal small intestine.
• Periampullary adenocarcinoma risk is high in Gardner syndrome and familial adenomatous polyposis.
• The risk also increases in gluten enteropathy and Crohn's disease.
• The most common symptom is abdominal pain. Obstruction, rarely perforation can be seen. In the future; weight loss, constitutional complaints, vomiting and jaundice can be seen.
Lymphoma
• They are most commonly located in the ileum in the small intestine.
• Primary lymphomas are usually T-cell non-Hodgkin lymphoma.
• Lymphoma risk is increased in Crohn's disease, immunodeficiency (post-transplantation, AIDS) and Celiac disease.
• Its clinical picture (mass, obstruction), diagnosis and treatment is similar to other small intestinal tumors.
Immunoproliferative small bowel disease (IPSID) is a type of lymphoma that diffuses the proximal small intestine.
It is also known as Mediterranean lymphoma or alpha-heavy chain disease. It is B-cell lymphoma. It typically presents with chronic diarrhea and malabsorption.
These patients have an abnormal secretion of IgA carrying the alpha heavy chain in the blood and intestines.
The disease is usually fatal with progressive malnutrition followed by the development of an aggressive lymphoma. Tetracycline is used in the treatment in the early stages of the disease.
Carcinoid Tumor (GI-NET) and Carcinoid Syndrome
• They are the most common endocrine tumors originating from enterochromaffin cells and seen in the gastrointestinal lumen.
• They are most commonly located in the ileum, then in the appendix. (This information is referred to as "infrequent appendix" in General Surgery).
• Clinical findings of these tumors due to the primary mass are usually seen in the late stage, and some of them cause carcinoid syndrome by secreting many hormonal peptides such as serotonin, histamine, neuron-specific enolase, insulin, ACTH, calcitonin, growth hormone, gastrin.
• Typical carcinoid syndrome begins with flushing, erythematous rash on the face and neck, palpitations, diarrhea and hypotension. In the progressive process, it leads to endocardial fibrosis in the heart. The tricuspid and pulmonary valves are most commonly involved, and fibrosis in the left heart valves is seen especially in the bronchial carcinoid.
• Midgut carcinoids (duodenum, small intestines, right colon) cause carcinoid syndrome more frequently. Carcinoid syndrome is seen less frequently in foregut carcinoids (lung, bronchi, stomach, pancreas) and very rarely in hindgut carcinoids (rectum, descending colon, ovary, testis).
• Colon and small intestine carcinoids metastasize more frequently than others.
Carcinoid syndrome due to intestinal carcinoids is usually seen after liver metastasis.
• Imaging tests for tumor localization are performed for diagnosis. In imaging, scintigraphy, CT and MRI are very valuable, but localization of the tumor is difficult and 5-HIAA (seratonin metabolite) measurement in 24-hour urine is diagnostic. In recent years, chromogranin A has also been used in serological diagnosis, but it is also elevated in the pancreas and other NETs and has a low specificity for intestinal carcinoids.
• Localization and diameter are important in prognosis. Rectal and appendix carcinoids, tumors smaller than 2 cm have a better prognosis.
• Treatment
If the tumor can be localized, it is surgical.
Octreotide (somatostatin analog) is the most effective drug for carcinoid syndrome.