1、Small Bowel Tumors第1頁Back groundSmall bowel tumours are rare, accounting for 3-6% of gastrointestinal gstrontestnl tumorsThe clinical presentation is non-specificSymptoms smptmz include anemia (貧血), gastro-intestinal bleeding (胃腸道出血), abdominal pain (腹痛) or small bowel obstruction (小腸梗阻)第2頁Back grou

2、ndThe most common small bowel malignancies:Adenocarcinoma dnk:snm LymphomalmfomCarcinoidk:sndGIST (Gastrointestinal stromal tumors) gstrontestnl 第3頁第4頁（HNPCC）Hereditary nonpolyposis colorectal cancer遺傳性非息肉病性大腸癌 hredteri遺傳 nn plposs 非息肉病kolrektl 結(jié)腸直腸Familial adenomatous polyposis 家族性腺瘤性息肉病 dnmts腺瘤（狀）

3、 plposs Peutz-Jegherssyndrome(PJS) 黑斑息肉?。―iff.Diagn.）differential diagnosisdfrnl danoss 判別診療aneurysmal dilatation njrzml dlten, dal-動脈瘤樣擴(kuò)張sclerosing mesenteritis sklrs mesnterats硬化性腸系膜炎第5頁Adenocarcinoma dnk:snm Adenocarcinoma represents 25-40% of all small bowel neoplasmsni:oplzmHowever colon carcin

4、oma koln krsnom is 50 times more common50% of small bowel adenocarcinomas occur in the duodenum du:di:nm and most of these are found with endoscopy end:skpi The jejunum ddu:nm is the second most prevalent site第6頁AdenocarcinomaStenotic lesion in the duodenum as a result of an adenocarcinoma (yellow a

5、rrow)Not possible to separate from the pancreas (red arrow)Pre-stenotic dilatation of the duodenum第7頁AdenocarcinomaThe typical imaging representation of a small bowel adenocarcinoma is a focal unilocular, circumferential mass with shouldering of the margins and obstructionLess frequently adenocarcin

6、omas present as an intraluminal polypoid mass, which can lead to intussusceptionUlceration is a quite common featureExtraluminal infiltration can present as fat stranding第8頁Adenocarcinoma A duodenal carcinoma presenting as irregular wall thickening in the distal duodenum (arrows)第9頁AdenocarcinomaAde

7、nocarcinomas often show moderate enhancementMetastases to the liver and peritoneum occur frequentlyShow a circumferential mass with shouldering borders第10頁AdenocarcinomaLarge adenocarcinomas can mimic a lymphomaThe images show an irregular mass in the proximal jejunumAlthough it is a large mass, the

8、 lumen is not obstructedThis proved to be an adenocarcinoma, but these findings could very well represent a lymphoma第11頁AdenocarcinomaHere a patient with extensive wall thickening of the proximal jejunum with aneurysmatic dilatationOn top of our differential diagnostic list would be a lymphoma, but

9、this proved to be an adenocarcinoma第12頁AdenocarcinomaFeatures that favour adenocarcinoma are fat stranding due to mesenteric fat infiltration and lymph node metastasesIn lymphoma fat stranding is uncommon, but lymph node metastases do occur and are usually more bulkyThe images show a short obstructi

10、ng circular mass in the jejunum (yellow arrow) with enlarged lymph node (red arrow)第13頁AdenocarcinomaThere is pre-stenotic dilatationPost-contrast T1W-image with fatsat (left) and T2W-image (right) show an obstructing mass in the jejunum with shouldering (arrow)第14頁AdenocarcinomaHere an adenocarcino

11、ma in the proximal jejunumThe mass is better depicted with MRI than with CT第15頁AdenocarcinomaHere a patient with active Crohns disease, who has a stenotic segment in the terminal ileumThis patient does not have an adenocarcinomaDiffuse wall thickening in the distal ileumComb sign: hypervascularity i

12、n the adjacent mesentery第16頁AdenocarcinomaThe adenocarcinoma located in the jejunumThere are multiple lymph nodes (red arrow) and there is fat stranding (yellow arrows)It should not be mistaken for mesenteric panniculitis as these large necrotic lymph nodes are pathologic第17頁LymphomaLymphomas make u

13、p about 20 % of all small bowel tumorsThe distal ileum is the most common site, owing to the large amount of lymphoid tissue that is present in the distal ileumThe typical presentation of a small bowel lymphoma is a thick walled infiltrating mass with aneurysmal dilatation without obstructionAneurys

14、mal dilatation is based upon destruction of the bowel wall and the myenteric nerve plexus第18頁LymphomaHere a typical presentationThere is irregular wall thickening of the terminal ileum with aneurysmatic dilatation第19頁LymphomaReversed fold pattern indicating celiac diseaseIleal-ileal intussusception

15、(yellow arrow), in a patient with multifocal small bowel lymphoma (not all lesions shown here).Mesenteric lymphadenopathy (red arrows).第20頁LymphomaHere another patient with celiac diseaseThere is an irregular mass in the jejunum with luminal dilatationThere is infiltration of the mesenteryPathology

16、showed a T-cell lymphoma in celiac diseaseThis is called enteropathy associated T-cell lymphoma (EATL)第21頁Carcinoid tumorCarcinoid tumors are rare neuroendocrine tumorsNeuroendocrine tumors of the small can be divided in well-differentiated - also known as carcinoid and poorly differentiated - small

17、 or large cell neuroendocrine carcinomaCarcinoid tumors constitute 2% of all gastrointestinal tumorsThe incidence of carcinoid tumors increased over the last decades, exceeding that of adenocarcinoma, making it the most common small bowel malignancy第22頁Carcinoid tumorThe most common location of a ca

18、rcinoid is the appendix, usually as an incidental finding following appendectomyThese images are of a patient who presented with peritoneal metastasesThe primary tumor proved to be a carcinoid of the appendix第23頁Carcinoid tumorHere a typical carcinoid presenting as a large mesenteric mass with desmo

19、plastic reaction and retraction of adjacent small bowel loops with wall thickening (arrows)第24頁Carcinoid tumorCarcinoid syndromeThe carcinoid syndrome occurs in approximately 5% of carcinoid tumors and becomes manifest when vasoactive substances from the tumors enter the systemic circulation.It commonly occurs in patients who have liver metastasesSymptoms include flushing and diarrhea and less frequently bronchospasm and heart failureThe heart failure is the result of serotonin-induced fibrosis of the c