| Summary: | Three situations mimic ulcerative colitis. First, in homosexual
men, acute self-limited colitis due to campylobacter, salmonella or shigella is
seen. Neisseria gonorrhea, herpes simplex, Chlamydia trachomatis and Entamoeba
histolytica or a combination of these may also be present. The second setting is
that of acquired immune deficiency syndrome (AIDS), where opportunistic
infections, cytomegalovirus, cryptosporidium, Salmonella typhimurium and Escherichiacoli 0157: H7 may cause diagnostic difficulty. The third situation is when
patients have recently returned from or are in an endemic area for infectious
diarrhea. This particularly affects the elderly, where salmonella, E coli 0157:H7,
shigellosis and, increasingly, pseudomembranous colitis secondary to cycotoxin
from Clostridium difficile, occur. The differential diagnoses for Crohn's disease
include such disparate conditions as solitary rectal ulcer in females, and ischemic
change in the elderly, which usually involves the splenic flexure area of the colon,
but may also involve the recrosigmoid area. When a mass is present in the right
lower quadrant, the differential diagnosis also includes local abscess formation
from a perforated appendix or foreign body, tuberculosis and carcinoma. In the
immunocompromised patient, Mycobacterium avium-intracellulare infection and
Kaposi's sarcoma may mimic inflammatory bowel disease. Yersinia enterocolitica
is becoming increasingly recognized as a cause of acute enteritis, predominantly
in the ileum, often with coexistent mesenteric adenitis. Drugs may also cause
diagnostic confusion. The one most recognized is antibiotic-associated pseudomembranous
colitis. However, cleansing soapsuds, Fleet (Frosst) and bisacodyl
enemas, methyldopa and Myochrysine (Rhone-Poulenc) may also cause colitis.
Nonsteroidal anti-inflammatory agents may produce ileal ulceration and a clinical
and radiological picture resembling Crohn's disease. Potassium chloride also
causes discrete ileal ulcers. Five case reports arc presented to illustrate these
diagnostic difficulties.
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