Opportunistic Intestinal Infections

Published on 19/07/2015 by admin

Filed under Radiology

Last modified 19/07/2015

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 Favors distal small bowel (SB) and colon

image Mucosal hyper- or hypoenhancement; submucosal edema
image Infiltration of mesenteric fat
image Lymphadenopathy is very uncommon
• Mycobacterial

image Mycobacterium avium-intracellulare  (MAI): Thickened SB folds with relatively little submucosal edema
image Tuberculosis (TB): Favors ileocecal distribution
image Mesenteric lymphadenopathy, often with low density (caseation)
image Exudative ascites (may mimic peritoneal carcinomatosis)
• Protozoan (Cryptosporidium, Microsporidia, and  Giardia

image Duodenum and jejunum, sparing distal SB and colon
image Fold thickening without much submucosal edema
image Excess fluid (luminal distention) of proximal small bowel
image No ascites; uncommon lymphadenopathy
• Bacterial (Clostridium difficile colitis, Campylobacter, and others)

image Segmental or, more commonly, pancolitis
image Striking mucosal hyperenhancement and submucosal edema
image Ascites (present in 40% of cases)
image May progress to toxic megacolon or perforation

TOP DIFFERENTIAL DIAGNOSES

• Gastrointestinal lymphoma

CLINICAL ISSUES

• Prevalence of opportunistic GI infections in HIV patients has markedly decreased with potent antiretroviral therapy

DIAGNOSTIC CHECKLIST

• Specific diagnosis can be suggested by CT
• Diagnosis depends on microbiological confirmation by analysis of bowel content or even biopsy
image
(Left) This young woman has cystic fibrosis and lung transplantation, with new onset diarrhea. Axial CECT shows hyperenhancement and submucosal edema image affecting most of the small bowel (SB).

image
(Right) Coronal CECT in the same patient shows the widespread enteritis with engorged mesenteric vessels image. The colon image is spared. Endoscopy and biopsy confirmed cytomegalovirus (CMV) enteritis.
image
(Left) This 35-year-old man with AIDS developed profuse diarrhea and abdominal pain. Axial CECT shows pancolitis with marked submucosal edema image but no hyperenhancement of the mucosa.

image
(Right) Coronal CECT in the same patient shows more evidence of pancolitis image, proven to be due to CMV, which may induce ischemic injury to both the SB and colon in immunocompromised patients.

TERMINOLOGY

Abbreviations

• 

Synonyms

Definitions

• Symptomatic gastrointestinal (GI) infection of immunocompromised host by organisms that usually cause no or minor illness in immunocompetent individuals

IMAGING

General Features

• Best diagnostic clue

image Cytomegalovirus (CMV): Mucosal hyper- or hypoenhancement; submucosal edema

– Distribution: Small bowel (SB), colon >  stomach, esophagus, rectum

image Favors distal small bowel and colon
– Pattern CECT: Mucosal hyper- or hypoenhancement

image Reflects active inflammation vs. ischemic necrosis
image Deep ulcers may be transmural, causing mesenteric infiltration
– Pattern on upper GI series, small bowel series, or barium enema

image Aphthoid erosions in earlier stages
image Deep ulcers, even sinus tracts in later stages
– Barium studies and CT findings may mimic Crohn disease or ulcerative colitis
– Associated findings

image Lymphadenopathy is very uncommon
image Infiltration of mesenteric fat by transmural, deep ulceration
image Mycobacterial

– Mycobacterium avium-intracellulare (MAI): Thickened SB folds with relatively little submucosal edema

image Micronodular fold thickening on SB follow-through
– Tuberculosis (TB)

image Favors ileocecal distribution
image Wall thickening, luminal narrowing, ± obstruction
– Associated findings

image Mesenteric lymphadenopathy, often with low density (caseation)
image Exudative ascites (peritonitis)
image Peritoneal and omental thickening (may mimic peritoneal carcinomatosis)
image Most affected patients do not have overt lung disease
image Protozoan (Cryptosporidium and Giardia)

– Distribution

image Duodenum and jejunum
image Ileum and colon are spared
– Pattern

image Fold thickening without much submucosal edema
image Excess fluid (luminal distention) of proximal small bowel
– Associated findings

image No ascites nor lymphadenopathy
image Bacterial (Clostridium difficile colitis, Campylobacter, and others)

– Distribution

image Segmental or, more commonly, pancolitis

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