Carcinoid Tumors, Intestinal

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WHO-ICD-10 version:2010

Neoplasms

Malignant neoplasms

OMIM Number

114900

Mode of Inheritance

Autosomal dominant

Gene Map Locus

11q23

Description

Intestinal carcinoid tumors are well-differentiated neuroendocrine tumors, which arise from glandular endocrine cells called enterochromaffin cells. Patients affected with this condition show symptoms of cramping intestinal pain, obstruction in the bowel movement, nausea, vomiting, diarrhea, and malnutrition due to malabsorption of nutrients. Most of these symptoms are due to obstruction of the bowel by the tumor, either due to the growth of the tumor into the intestinal lumen, or due to fibrosing mesenteritis causing small intestinal kinking and gangrene. Some of the patients, however, go on to develop carcinoid syndrome, caused by the excess production of hormone by the tumors. Carcinoid syndrome is characterized by hot flushes of the head and neck, and cyanosis. About one in every 300 individuals is said to be affected by intestinal carcinoid tumors. However, in the majority of these patients, the tumors are too small to cause any untoward effect, and remain undetected. This is one of the reasons for the late detection of these tumors, and for its spread to local tissues and lymph nodes.

Carcinoid tumors can be detected in a variety of ways. Assaying the amount of urinary 5-hydroxy indole acetic acid is one of the major methods. Other diagnostic tests include CT, MRI, arteriography, and radionuclide scanning. Biopsies of the tumors can also confirm the diagnosis, as the enterochromaffin cells stain in a peculiar way. If tumors cause obstruction in the intestine, they need to be surgically removed. Destroying the tumor also reduces the hormonal effect exerted by them. The most effective type of chemotherapy involves combination therapy with several anti cancer drugs. On the whole, the survival rate of patients affected with carcinoid tumors is good, with survival up to 23 years being noted.

The tumor suppressor gene, SDHD (Succinate-Ubiquinone Oxidoreductase Subunit D) has been found to be responsible for the development of intestinal carcinoid tumors. Heterozygous sequence variants of the SDHD gene were detected in at least a small number of patients. Characterized mutations in the SDHD gene, known to lead to development of intestinal carcinoids include H50R and G12S.

Epidemiology in the Arab World

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Other Reports

Oman

Machado and Grant (2001) reported two cases with carcinoid tumors of the small bowel which presented with obscure gastrointestinal bleeding. Case 1 was a 53-year old hypertensive and diabetic female with a history of previous stroke. She presented with acute per rectum bleeding and her hemoglobin was found to be 5.9g/dl. The history of bleeding was since 18 months ago, but no cause could be identified as all gastrointestinal investigations (upper GI endoscopy, colonoscopy, small bowel contrast study and technetium-tagged red blood cell [Tc-RBC]) were normal, and she was put on iron supplements. A further investigation with mesenteric angiography six months later was negative. At this admission, Tc-RBC scan revealed an uptake in the ileum, which on mesenteric angiograms, evinced two small areas of localized enhancement with a tumor blush. After transfusion, an exploratory operation was done and pooling of blood was noticed in the terminal ileum which was confirmed by an enteroscopy. Two ileal submucosal nodules (5mm in diameter and 5cm apart) were found with one oozing from a minute ulceration. These were resected as a single 10 cm segment of ileum and end to end anastamosis was done. These nodules were histologically diagnosed as carcinoid tumors. The postoperative period was uneventful with no further gastrointestinal bleeding and the patient was discharged and a repeat MIGA scan was normal. The patient remained to be symptom-free five years after the operation. Case 2 was a 48-year old male who presented with anemia and occasional upper abdominal pain for 18 months. Investigations revealed low hemoglobin of 7.1 g/dl, microcytic hypochromic anemia, and occult blood in stools in three occasions. As in case 1, initial gastrointestinal investigations were normal, and he was prescribed iron supplements. After three months, he presented with three episodes of melena but upper GI endoscopy and Tc RBC scan were normal. He refused further investigations only to come back after a year with similar complaints and when a repeat Tc-RBC scan was done, an uptake in the jejunum was evident and arteriography showed a tumor blush in the jejunum. At laprotomy, a palpabe, visible nodule (1.5 cm diameter) was found on the antimesenteric border of the jejunum 20 cm away from the duodenojejunal flexure, which was resected and normality of the rest of the remaining small bowel was confirmed by an enteroscope, and this was followed up by end to end anastamosis. Macroscopically, the nodule was submucosal with a 3 mm diameter mucosal ulceration overlying it and microscopically was confirmed to be a carcinoid tumor. He was discharged symptom free and a MIBG scan after one year was negative and for four years, the patient remained asymptomatic.

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