Small Intestine: Differential Diagnosis

Chapter Outline
Small Bowel Folds and Mucosal Changes
Table 50-1.

Normal Small Bowel Parameters
Table 50-2.

Small Bowel Lumen Dilated, Normal Fold Thickness
Table 50-3.

Smooth, Straight, Thickened Folds
Table 50-4.

Micronodularity
Table 50-5.

Irregular Fold Thickening, Diffuse
Table 50-6.

Irregular Fold Thickening, Proximal Small Bowel
Table 50-7.

Irregular Fold Thickening, Distal Ileum
Table 50-8.

Tubular Bowel with Luminal Narrowing
Table 50-9.

Tubular Bowel without Luminal Narrowing
Table 50-10.

Solitary Polyp
Table 50-11.

Multiple Polyps and Polyposis Syndromes
Table 50-12.

Multiple Target Lesions
Table 50-13.

Annular Lesion with Shelflike Margins
Table 50-14.

Annular Lesion with Tapered Edges
Table 50-15.

Exoenteric Cavitary Lesions
Table 50-16.

Separation of Bowel Loops without Tethering
Table 50-17.

Mass Effect with Tethering of Mucosal Folds
Table 50-18.

Site Predilection of Diseases

The tables in this chapter ( Tables 50-1 to 50-18 ) concerning the differential diagnosis of small bowel diseases are not meant to be exhaustive. Instead, these tables present an approach for classifying the most common causes of various radiographic abnormalities in the small bowel in relation to the size, location, distribution, and radiographic characteristics of these abnormalities. A list of references is included for further reading.

TABLE 50-1

Normal Small Bowel Parameters

Parameter	Jejunum	Ileum
NORMAL PARAMETERS FOR ENTEROCLYSIS
Folds per inch length	4-7	2-4
Thickness of folds (mm)	1-2	1.0-1.5
Diameter of lumen (cm)	≤4	≤3
Wall thickness (mm)	1.0-1.5	1.0-1.5
NORMAL PARAMETERS FOR SMALL BOWEL FOLLOW-THROUGH
Thickness of folds (mm)	2-3	1-2
Diameter of lumen (cm)	≤3	≤2

Data from references .

TABLE 50-2

Small Bowel Lumen Dilated, Normal Fold Thickness

Parameter	Cause	Comments
Diffuse small bowel dilation	Mechanical obstruction, small bowel or colon	Air-fluid levels on abdominal radiographs. CT if high grade obstruction suspected, barium studies for partial or intermittent obstruction Common causes—adhesions, hernias, metastases, radiation enteropathy, colonic carcinoma with backup into dilated small bowel
	Adynamic ileus	Air-fluid levels to distal small bowel and in colon Common causes—postoperative, medications, ischemia, vagotomy Less common causes—systemic sclerosis (dilated duodenum, hidebound small bowel), amyloidosis, peritonitis, electrolyte imbalances (hypokalemia, uremia), blunt trauma, diabetes, hypothyroidism
Focal small bowel dilation	Proximal obstruction	Fluid levels in few small bowel loops in upper abdomen—primary adenocarcinoma, postoperative strictures, adhesions
	Focal adynamic ileus	Pancreatitis, postoperative manipulation or leak, pelvic irradiation
	Closed-loop obstruction Adhesions	Group of air-fluid levels unchanging in position CT for diagnosis and evaluation of possible strangulation
	Internal hernia	Focal region of dilated loops with air-fluid levels

Data from references .

TABLE 50-3

Smooth, Straight, Thickened Folds

Parameter	Cause	Comments
Diffusely distributed	Edema	Hypoalbuminemia—cirrhosis, nephrotic syndrome Protein-losing enteropathy Congestive heart failure Portal hypertension
Focal smooth fold thickening	Intramural hemorrhage Ischemia	Segmental stack of coins appearance; interspace spikes; thumbprinting on mesenteric border
	Anticoagulants	Most patients return to normal within 2-3 wk
	Coagulopathies
	Superior mesenteric vein thrombosis
	Vasculitides	Ischemic changes, hemorrhage, ulceration or necrosis with small vessel disease (lupus, Henoch-Schönlein purpura)
	Blunt trauma	CT—look for possible perforation (e.g., mesenteric haziness or fluid, thickened bowel wall, lack of bowel contrast enhancement, focal pneumatosis, free intraperitoneal gas)
	Radiation enteropathy	Thickened folds, narrow interfold spaces (interspace spikes); barium changes resemble picket fence Changes confined to radiation portal

Data from references .

TABLE 50-4

Micronodularity *

Cause	Comments
Whipple’s disease	White males with arthralgias, cardiovascular and neurologic symptoms CT—low-attenuation mesenteric lymph node mass
Mycobacterium avium-intracellulare (MAI) complex enteritis	AIDS MAI-laden macrophages in lamina propria CT—shows necrosis in enlarged lymph nodes
Abetalipoproteinemia	Adolescent with retinitis pigmentosa, acanthocytosis, spinocerebellar degeneration Retained fat globules in villous enterocytes
Histoplasmosis	Histoplasma -laden macrophages in lamina propria
Lymphangiectasia	Villi enlarged by dilated lacteals in primary form Edema in submucosa Mesenteric adenopathy causes secondary form
Macroglobulinemia	Lymphoma—may occur IgM macroglobulin in lamina propria
Radiation therapy	Associated with smooth, thickened, straight folds
Crohn’s disease	Distal, terminal ileum Aphthoid ulcers, mesenteric border ulcers; cobblestoning; strictures, fissures, fistulae

Data from references .

* 1- to 2-mm mucosal nodules. Micronodularity implies villous enlargement caused by an infiltrative process in lamina propria. This table lists diseases that often involve the mucosa and submucosa and also produce abnormal folds.

TABLE 50-5

Irregular Fold Thickening, Diffuse

Cause	Comments
Lymphangiectasia, primary	Submucosal edema plus micronodularity Congenital hypoplasia of lymphatics
Lymphangiectasia, secondary	Small bowel changes (as above) Obstruction of lymph drainage by retroperitoneal fibrosis, radiation, mesenteric lymphadenopathy (Whipple’s, lymphoma)
Amyloidosis, types AA and AL	Fold thickening if deposits in vessels cause ischemia. Micronodularity in secondary amyloidosis—reflects amyloid deposits in lamina propria 4- to 10-mm nodules in submucosa (AL)
Mastocytosis	Histamine release–associated headaches, flushing, diarrhea; urticaria pigmentosa (50%), bone lesions (20%) Stomach, duodenum—ulcers Small bowel—multiple urticaria-like nodules Thickened folds often segmental
Immunoproliferative small intestinal disease (IPSID)	Relates to multiple parasitic and/or bacterial infections Patient from Mediterranean region Extensive lymphoid hyperplasia Responds to treatment
Mediterranean lymphoma	Young patient with progression of IPSID to monoclonal lymphomatous infiltrate Lymphoid nodules enlarged, nonuniform, confluent Lymph node masses Associated with a heavy-chain disease
AIDS	Large variety of infections cause diffuse thickened folds.
Graft-versus-host disease	Often with cytomegalovirus infection (see Table 50-8 )

Data from references .

TABLE 50-6

Irregular Fold Thickening, Proximal Small Bowel

Cause	Comments
T-cell lymphoma complicating celiac disease	Diarrhea recurs despite gluten-free diet Nodular fold thickening in long segments May have annular lesions
Ulcerative jejunoileitis	Complicates celiac disease Before inflammatory infiltrate changes to monoclonal lymphoma Radiographically indistinguishable from T-cell lymphoma
Tropical sprue	History of sojourn in tropics Unlike celiac disease, folds are thickened, no separation of jejunal folds
Zollinger-Ellison syndrome	Gastric and duodenal ulcers Increased intraluminal fluid
Strongyloidiasis	Effaced folds, tubular bowel contour with severe disease
AIDS-related infections	Mycobacterium avium-intracellulare (MAI) complex, isosporiasis, cryptosporidiosis
Gastrojejunostomy	Thick folds in efferent loop just distal to gastrojejunal anastomosis
Jejunosotomy tube	Reaction to tube feeds