EXERCISE 10-3. SMALL-BOWEL BLEEDING
10-9. What is the most likely explanation for the abnormal small-bowel loop anterior to the bladder (B) on this contrast-enhanced CT examination of the lower ab-domen in Case 10-9 (Figure 10-30)?
A. Crohn disease
C. Whipple disease
D. Ulcerated lymphoma
E. Small-bowel metastases
10-10. What is the most likely cause of the saccular structure
A. seen in the distal small bowel in Case 10-10 (Figure 10-31)?
B. Normal loop of small bowel
C. Large small-bowel ulcer
D. Meckel diverticulum
E. Ulcerated primary malignancy
F. Small-bowel metastases
10-11. What is the least likely etiology of the diffuse fold thickening in the central small bowel in Case 10-11 (Figure 10-32)?
A. Ischemic enteritis
B. Small-bowel hemorrhage
C. Radiation enteritis
D. Small-bowel edema
E. Small-bowel malignancy
10-12. What is the least likely possibility to explain the irregular, ulcerated small-bowel lesion in Case 10-12 (Figure 10-33)?
A. Ulcerated GIST
B. Lymphoma with ulceration
C. Metastatic ulcerated mass
D. Large benign ulcer of small bowel
E Adenocarcinoma with ulceration
10-9. The segmental and enhancing wall thickening in the ileum is most consistent with Crohn disease; tuberculosis might appear similar but is rare, and most neoplasms of the small bowel are focal (A is the correct answer to Question 10-9).
10-10. The smooth, saccular structure of the small bowel proved to be a bleeding Meckel diverticulum; benign ulcers of the small bowel are rare, and ulcerated ma-lignancies are usually irregular in appearance (C is the correct answer to Question 10-10).
10-11. The long segment of small bowel of normal caliber with smooth fold thickening (ie, valvulae con-niventes) suggests submucosal infiltration from fluid (eg, edema or blood), which may have many causes but not small-bowel malignancy; ischemic enteritis was the etiology (E is the correct answer to Question 10-11).
10-12. The irregular, ulcerated mass of the small bowel is typical for an ulcerated malignancy of various histo-logic types, including metastatic neoplasms; the cause was a lymphoma (D is the correct answer to Question 10-12).
Small-bowel bleeding and obstruction can be caused by a wide assortment of diseases, some of which may present with both signs. Crohn disease and ischemia of the small bowel are likely the two most common causes in younger and older pa-tients, respectively.
Crohn disease is an inflammatory disorder of the gas-trointestinal tract of unknown etiology. The small bowel and the ileocecal region are the most common sites of involve-ment. Crohn disease may affect a single segment, often the terminal ileum, or multiple areas of the small bowel with normal intervening loops (ie, skip areas). The involved loop(s) is usually narrowed with a nodular mucosal surface due to ulceration; deep ulcers and sinus tracts may progress to fistulas. Mark narrowing of the bowel lumen may relate to active inflammation and spasm with wall thickening or to fi-brotic stenosis (Figure 10-34). CT and MR imaging with in-travenous contrast enhancement are now commonly used to determine the activity of Crohn disease and to help with clin-ical management (Figure 10-35).
Meckel diverticulum is one of the most common anomalies of the gastrointestinal tract and occurs in about 2% to 3% of the population. The diverticulum is usually asymptomatic and is found incidentally, but may be a cause of intestinal bleeding if the structure contains ulcerated ectopic gastric mucosa. When shown on radiographic examination of the small bowel, especially using the enteroclysis technique, Meckel diverticu-lum appears as a changeable saccular outpouching along the antimesenteric border of the bowel within a short distance from the ileocecal junction. A rarer complication of a Meckel diverticulum is inversion into the lumen of the small bowel with subsequent intussusception and obstruction.
Ischemic disease of the small intestine can be caused by nonobstructive hypoperfusion of the organ or result from thrombotic or embolic vascular disease. The radiographic findings are variable depending on the extent and severity of the underlying process and its duration. Small-bowel dilatation from ileus or narrowing due to spasm and sub-mucosal edema and hemorrhage are additional appear-ances; these changes are also evident on CT and MR imaging, both of which offer further advantages in assess-ment of the bowel wall, the detection of pneumatosis, and the evaluation of the mesenteric vessels using CTA or MRA (ie, CT or MR angiography). Submucosal infiltration of the small bowel as seen in ischemic enteritis may occur in other disorders and have similar appearances, such as small-bowel hemorrhage related to anticoagulants, trauma, hemophilia, or vasculitis; radiation enteritis is an-other consideration (Figure 10-36). Small-bowel ischemia may resolve spontaneously or progress to perforation; stricture is a late complication.
Primary small-bowel neoplasms are rare. Benign neoplasms of the small intestine are less often symptomatic compared to malignancies. Adenomas, lipomas, and GISTs/leiomyomas are the most common benign neoplasms but make up only 60% of the benign total because of a large number of miscella-neous rarities. Symptomatic small-bowel neoplasms are usually malignant and nearly all are adenocarcinoma, lym-phoma, carcinoid tumor, or malignant GIST. These malig-nancies, along with metastatic neoplasms of the small bowel, show a wide spectrum of appearances varying from polypoid and ulcerated masses to multifocal and infiltrative processes (Figure 10-37).
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