Crohn’s Disease - DIFFERENTIAL DIAGNOSIS

Posted by Alex

Patients with irritable bowel syndrome rarely present with “inflammatory” features. Persistent symptoms despite therapy for presumed irritable bowel syndrome (especially in the presence of weight loss), bleeding attributed to “hemorrhoids,” or a family history of IBD deserve a more comprehensive evaluation to exclude IBD. Most enteric infections are self-limited. Viral gastroenteritis typically lasts 1 to 4 days without rectal bleeding or fecal leukocytes. Most bacterial pathogens produce self-limited disease lasting less than 7 to 14 days, despite intermittent rectal bleeding, fevers, fecal leukocytes, and a mucosal appearance that may be indistinguishable from that of UC or CD. Occasionally, Campylobacter jejuni produces protracted symptoms and Clostridium C. difficile toxin-induced colitis can mimic the symptoms, signs, and endoscopic appearance of UC or CD. When a patient with IBD presents with new or exacerbated symptoms, stool cultures for enteric pathogens and studies for C. difficile toxin should be obtained, especially if the patient has been recently treated with antibiotics. In Northern Europe and Canada, Yersinia enterocolitica infection can mimic terminal ileitis. If the clinical suspicion warrants, cultures and serologic studies for Yersinia should be obtained. Similarly, tuberculosis of the gastrointestinal tract may mimic CD in geographic areas where intestinal tuberculosis is edemic, and, rarely, Actinomycosis simulates fistulizing CD.

Chronic intestinal infections usually are parasitic. Amebiasis may cause diarrhea, rectal bleeding, and a sigmoidoscopic appearance similar to that of idiopathic IBD. Deep “collar button” ulcerations are similar to focal ulcerations of CD. Fresh stool specimens should be examined repeatedly for amebic cysts or trophozoites; biopsies may be indicated in patients who have been exposed to endemic environments (e.g., nursing home residents and homosexual men). Syphilis, gonorrhea, and lymphogranuloma venereum also induce proctitis in gay men. HIV diarrhea should be excluded by serologic studies in patients with suspected exposure.

Occasionally, with an acute onset, Crohn’s ileitis is diagnosed at laparotomy performed for presumed appendicitis. Likewise, in young individuals with acute right lower quadrant pain, mesenteric adenitis may mimic the symptoms of CD. In the older population, ischemic bowel disease, especially chronic mesenteric ischemia, or recurrent diverticulitis can mimic Crohn’s colitis.

Persistent rectal bleeding should not be attributed to hemorrhoids unless a flexible sigmoidoscopy has excluded IBD. In older people, colonic carcinomas also can produce chronic symptoms and intermittent rectal bleeding. Intestinal lymphoma may be difficult to distinguish from CD and often requires a surgical diagnosis when suspected. Radiation enteritis is limited to patients with a history of that therapy. Some patients receiving chemotherapy or gold develop diarrhea and mucosal ulceration. Eosinophilic gastroenteritis presents with diarrhea, malabsorption, and protein-losing enteropathy, but the associated peripheral blood eosinophilia and biopsies are distinguishing. The diffuse, proximal malabsorptive pattern of celiac sprue, associated with diffuse villous atrophy, is distinct from the focal, distal small bowel changes of CD. Table 104-4 outlines the distinguishing features between UC and CD confined to the colon.

NSAID-induced ulceration of the ileum and colon is the most commonly encountered drug-related enterocolitis owing to prevalent NSAID use. The incidence of subclinical NSAID-induced damage to the gut mucosa is high (over one-third of exposed individuals). Diffuse or focal ulceration including aphthous ulcers is common and may complicate the predisposed vulnerability of mucosa in the elderly resulting from ischemia or diverticular disease. NSAID exposure may also predispose to newer variants of colitis such as collagenous colitis and microscopic colitis. The latter are recently described colitides causing diarrhea and epithelial or subepithelial

 
TABLE 104-4 - A COMPARISON OF THE CLINICAL AND PATHOLOGIC FEATURES OF CROHN’S COLITIS AND ULCERATIVE COLITIS

Feature	Crohn’s Colitis	Ulcerative Colitis
Clinical
Smoker	++	+/-
Malaise, fever	++	+
Rectal bleeding	++	+++
Abdominal tenderness	+++	+
Abdominal mass	++	-
Abdominal pain	+++	+
Perianal disease	+++	-
Endoscopic
Rectal disease	+	+++
Diffuse, continuous symmetric involvement	+	+++
Aphthous or linear ulcers	+++	-
Cobblestoning	++	-
Friability	++	+++
Radiologic
Continuous disease	+	+++
Ileal involvement	++	-
Asymmetry	+++	-
Strictures	++	+
Fistulas	++	-
Pathologic
Discontinuity	++	-
Transmural involvement	+++	+/-
Lymphoid aggregates	+++	-
Crypt abscesses	+++	+++
Granulomas	++	-
Sinus tract/fistula	+++	-
+++ = Always; ++ = common; + = occasional; - = never.

histologic findings in the absence of identifiable endoscopic lesions. When suspected as a causative factor or in the setting of IBD, NSAID’s should be discontinued and avoided.