| disease | Small Intestinal Tumor |
The small intestine accounts for 75% of the entire gastrointestinal tract, but small intestine tumors only make up 3–6% of gastrointestinal tumors, with malignant tumors of the small intestine representing 1% of gastrointestinal malignancies. The length ratio of the small intestine to the colon is 4:1, and the mucosal surface area ratio is 10:1, yet the tumor ratio between the two is roughly 1:40. Freund summarized several reasons for the low incidence of small intestine tumors: the intestinal contents are alkaline and pass through quickly, reducing contact between the intestinal mucosa and carcinogens as well as mechanical irritation; the small intestine has a low bacterial count, thereby decreasing the formation of carcinogens; protective enzymes are present, which detoxify potential carcinogens; it contains high concentrations of immunoglobulin A, capable of neutralizing potential cancer-causing toxins; and the intestine forms later in embryonic development, avoiding the implantation of atypical tissues.
bubble_chart Epidemiology
Small intestine tumors can be benign or malignant, with similar incidence rates. From 1979 to 1988, the General Surgery Department of Shanghai Zhongshan Hospital treated 67 cases of small intestine tumors, including 21 cases of duodenal tumors and 46 cases of jejunal and ileal tumors. Among the 67 cases, 34 were malignant and 33 were benign, with a ratio of 1:1. Both benign and malignant tumors were most commonly leiomyomas or leiomyosarcomas. In a domestic report by Yin Chaoli et al., among 40 cases of benign small intestine tumors, leiomyomas were also the most common (24 cases), followed by hemangiomas (7 cases), adenomas (6 cases), and one case each of lipoma, neurofibroma, and cystic lymphangioma. International data indicate that benign small intestine tumors are also most frequently leiomyomas and adenomas, followed by lipomas, hemangiomas, and fibromas. Among malignant small intestine tumors, sarcomas account for about 40%, adenocarcinomas 30%, and carcinoids approximately 25%. Both benign and malignant tumors can occur in any segment of the small intestine, including the duodenum, jejunum, and ileum.
bubble_chart Clinical ManifestationsSmall intestine tumor diseases are more common in people under 50 years old, with an average age of around 35. The incidence is roughly equal between males and females. The common clinical manifestations of small intestine tumors are as follows:
1. Abdominal pain — A common symptom, which may be caused by ulceration of the tumor surface irritating the intestine and leading to intestinal spasms, or by intestinal obstruction or intussusception. When the tumor is large and protrudes into the intestinal lumen, it can cause blockage; tumor invasion of the intestinal wall can lead to stenosis or obstruction. This type of obstruction is more common in malignant small intestine tumors. Intussusception is mostly caused by benign small intestine tumors. It can occur acutely or as recurrent chronic episodes.
2. Gastrointestinal bleeding — About one-third to two-thirds of patients experience bleeding due to ulceration of the tumor surface. Most cases involve occult bleeding, manifesting as positive fecal occult blood tests or melena, which over time may lead to iron-deficiency anemia. Intermittent minor bleeding or even massive hematochezia may also occur. The tumors most likely to cause bleeding are leiomyomas, fleshy tumors, hemangiomas, adenomas, and neurofibromas.
3. Abdominal mass — Due to the high mobility and variable position of the small intestine, small intestine tumors may occasionally be palpable during physical examination, but sometimes they cannot be felt, appearing intermittently. Palpable masses are mostly larger fleshy tumors of the small intestine.
4. Systemic symptoms — In addition to anemia caused by recurrent tumor bleeding, malignant small intestine tumors can also lead to systemic symptoms such as weight loss and lack of strength.
Most patients with small intestine tumor diseases, whether benign or malignant, seek medical attention due to abdominal pain and melena or hematochezia. If preliminary examinations rule out common disease causes, or if a comprehensive evaluation still fails to establish a diagnosis, the possibility of small intestine tumors should be considered, and further investigations should be conducted.
First, an intestinal X-ray examination should be performed. If duodenal lesions are suspected, hypotonic duodenography can be conducted. Barium examination of the jejunum and ileum is more challenging because the contents of the small intestine move relatively quickly; additionally, the small intestine is lengthy and convoluted within the abdominal cavity, causing overlapping images that are difficult to distinguish. If the tumor is large and protrudes into the lumen, a filling defect may be observed. If the tumor infiltrates a wide area of the intestinal wall or causes intussusception, proximal small intestine dilation, barium obstruction, stenosis, or cup-shaped shadows may be seen; sometimes, mucosal destruction may also be visible. When the tumor is small and does not cause stenosis or obstruction, traditional small intestine barium examinations may fail to detect the lesion. In recent years, small intestine barium enema methods have shown some promise. However, barium examinations should not be performed in cases of complete or near-complete obstruction to avoid exacerbating the obstruction.
For gastrointestinal bleeding with an estimated bleeding rate exceeding 3–5 ml per minute, selective angiography of the celiac and superior mesenteric arteries can be performed to localize the bleeding site.
Abdominal CT scans can reveal the approximate location and size of small intestine tumors, their relationship with the intestinal wall, as well as the presence of liver metastases, para-aortic lymphadenopathy, or hilar lymph node enlargement. However, small tumors with a diameter below 1.5 cm are often difficult to detect.
Many small intestine tumors remain undiagnosed despite the aforementioned examinations. In such cases, exploratory laparotomy may be considered if necessary. There are even instances where multiple surgeries are required to establish a definitive diagnosis, highlighting the diagnostic challenges posed by small intestine tumors.
bubble_chart Treatment Measures
Benign tumors of the small intestine can cause complications such as bleeding and intussusception. Without histological examination, their nature cannot be definitively determined, so surgical resection is generally required. Smaller tumors can be locally excised along with the surrounding intestinal wall, while most cases require segmental intestinal resection with end-to-end anastomosis.
For malignant tumors of the small intestine, surgery involves a wider resection of the affected intestinal segment and regional lymph nodes, followed by anastomosis. If the tumor is located in the duodenum, a pancreaticoduodenectomy (Whipple procedure) is often necessary.
If the small intestine tumor is locally fixed and unresectable, a bypass procedure may be performed to relieve or prevent obstruction.
Early diagnosis of malignant small intestine tumors is challenging, with a resection rate of approximately 40%. The 5-year survival rate after resection is about 40% for leiomyosarcomas, 35% for lymphomas, and 20% for adenocarcinomas.
Apart from lymphomas, radiotherapy and chemotherapy generally have limited efficacy.
Benign tumors of the small intestine can cause complications such as bleeding and intussusception; a few malignant tumors may progress to an advanced stage, leading to intestinal perforation, diffuse peritonitis, or chronic perforation, resulting in abscess formation or internal fistulas.
