How is CMV colitis diagnosed and treated?

From the Guidelines

CMV colitis is diagnosed through a combination of clinical evaluation, endoscopy with biopsy, and laboratory testing, with the gold standard being CMV-specific immunohistochemistry in tissue biopsies 1. The diagnosis of CMV colitis typically begins with colonoscopy, which may reveal mucosal ulcerations, erosions, or inflammation.

• Key findings on endoscopy include ulcerations with a well-defined, punched-out appearance, present in up to 80% of patients 1.
• A biopsy is always required when colonoscopy is performed, and histopathological examination of colonic biopsies showing characteristic viral inclusions ("owl's eye" appearance) is essential for diagnosis.
• Blood tests, including CMV PCR, CMV antigenemia, and CMV IgM antibodies, can support the diagnosis but are not sufficient alone.
• Contrast-enhanced CT scan can also be helpful in diagnosis, with bowel thickening being almost always present, but pancolic appearance is rare and may help in differential diagnosis with other conditions 1.

Treatment primarily involves antiviral medications, with ganciclovir being the first-line therapy at 5 mg/kg intravenously twice daily for 2-3 weeks, followed by oral valganciclovir at 900 mg twice daily 1.

• Alternative treatments for ganciclovir-resistant cases include foscarnet (90 mg/kg twice daily) or cidofovir (5 mg/kg once weekly).
• Immunosuppressive medications should be reduced when possible in immunocompromised patients.
• Treatment response should be monitored with repeat endoscopy and CMV PCR testing.
• Supportive care, including fluid management, electrolyte replacement, and nutritional support, is also essential during the treatment period.
• In severe cases, surgical intervention, such as subtotal or partial colectomy, may be necessary, especially in cases of toxic megacolon, fulminant colitis, perforation, or ischemia 1.

From the Research

Diagnosis of CMV Colitis

• CMV colitis is generally associated with an immunosuppressed state 2
• Presenting symptoms of CMV colitis include:
  • Bloody stools 2, 3
  • Abdominal pain 2, 3
  • Diarrhea 2, 3
• Imaging findings:
  • Pericolonic stranding 2
  • Bowel wall thickening 2
• Endoscopic evaluation:
  • Inflammation 2, 3
  • Ulceration 2, 3
  • Erythema 2
• Diagnostic tools:
  • Quantitative real-time PCR assay for detecting CMV-DNA in inflamed colonic mucosa 4
  • 18F-FDG PET/CT scan can reveal pathological uptake in the colon mucosa, but may mimic activity of inflammatory bowel disease (IBD) 5
  • Biopsies from the intestinal mucosa can detect CMV DNA 5

Treatment of CMV Colitis

• Treatment options:
  • Valganciclovir alone 2
  • Ganciclovir followed by valganciclovir 2
  • High-dose valganciclovir for resistant CMV colitis due to UL97 and UL54 mutations 6
  • Foscarnet for ganciclovir-resistant CMV colitis, but may need to be discontinued due to acute kidney injury 6
• Importance of early and accurate diagnosis for prompt and appropriate treatment 4