An uncommon cause of lower gastrointestinal bleeding: a case report

Carcinoid tumors are apudomas that arise from enterochromaffin cells throughout the gut. Small bowel carcinoids are most commonly found in the ileum, within 60 cm of the ileocecal valve [1]. The presence of multiple synchronous nodules mandates careful inspection of the entire small intestine to exclude other sites of disease. Grossly, carcinoid tumors appear as firm intramucosal or submucosal nodules, with a yellow cut surface due to their high lipid content. Microscopically, solid nests of uniform small cells with round or oval nuclei are present which show little or no cellular pleomorphism, hyperchromasia, or increased mitotic activity [2]. Because of their indolent growth, most small bowel carcinoids are asymptomatic at presentation and found incidentally. In symptomatic patients, abdominal pain is the most common initial symptom. The pain is most often vague and nonspecific. Intermittent obstruction occurs in 25 percent of all small intestinal carcinoids. Obstruction may be caused by intraluminal tumor, but often results from mesenteric kinking and distortion brought on by tumor invasion and a secondary desmoplastic response [2–4]. Carcinoid syndrome occurs in approximately 10 percent of intestinal tumors, usually in an advanced metastatic stage [2, 3]. While rectal carcinoid tumors can present with bleeding, massive bleeding is not a usual feature of carcinoid tumor [1].

Any bleeding distal to ligament of Treitz is considered as lower gastrointestinal bleeding. Most cases of lower gastrointestinal bleeding involve the colon (85%), approximately 10% are actually due to upper gastrointestinal bleeding and only 3% to 5% cases are secondary to bleeding from small intestine [1, 2]. While rectal carcinoids may represent more often with lower gastrointestinal bleeding (LGI), small bowel carcinoids can rarely be a cause of obscure bleeding and extremely rarely would cause massive lower gastrointestinal bleeding. A literature search, using PubMed (March 31^st, 2008) reveals only three cases reported for LGI bleed caused by small bowel carcinoid tumor [5–9]. To our knowledge it appears our case would be the first such to be reported from North America that has been histologically confirmed. Despite its rarity small bowel carcinoids should always be considered in the differential diagnosis of LGI bleeding because they are highly infiltrating and contrary to popular belief may cause significant morbidity.

The etiology of massive LGI bleed includes diverticulosis, angiodysplasia, polyps, dieulafoy's lesion, infectious or inflammatory bowel disease [Table 1]. Carcinoid tumors are rare but most common GI neuroendocrine tumors. Small intestinal carcinoids are usually in the ileum and often multiple and rarely present with lower GI bleeding. A literature search using the search engines PubMed & Ovid reveals only three cases reported for LGI bleed caused by small bowel carcinoid tumor [5–10]. Small bowel carcinoid tumors usually present in the sixth or seventh decade of life with abdominal pain or obstruction [1–4]. Symptoms of carcinoid syndrome i.e. flushing, diarrhea are infrequent; occur in less than 10% of patients [3].

Our patient was unique in that he was younger and did not have any of the typical symptoms. He presented with massive LGI bleed which is unusual for small bowel carcinoid that tends to be slow growing and may remain asymptomatic. Further, as demonstrated in our patient, standard endoscopic examination may miss them. Thus these are difficult to diagnose and as in our patient maybe rarely detected before a surgical procedure. As the carcinoid tumor is highly infiltrating early diagnosis is mandatory. Thus a high index of suspicion and the utilization of other modalities for complete examination of the small bowel such as capsule endoscopy, mesenteric angiography, and radionuclide RBC scan should be considered in patients with LGI hemorrhage in whom EGD and colonoscopy are negative.

Carcinoid tumors can cause massive lower GI bleeding. Because of a substantial false-negative rate for lesions on initial endoscopy as demonstrated in our patient, and also because of the fact that small bowel carcinoid tumors are highly infiltrating thus mandating early diagnosis; an aggressive approach should be taken.

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.