Colitis nucleomigrans: The third type of microscopic colitis (part 1).

Area of Science:

• Gastroenterology
• Pathology
• Colorectal Diseases

Background:

• Microscopic colitis (MC), including collagenous and lymphocytic colitis, presents with chronic diarrhea and normal endoscopic findings.
• Distinct histopathological features define MC, but a third type has been proposed.

Purpose of the Study:

• To propose and define a new entity, colitis nucleomigrans (CN), as a potential third type of microscopic colitis.
• To establish histopathological criteria for CN and analyze its clinical and endoscopic features.

Main Methods:

• Retrospective review of biopsied nonspecific colitis specimens.
• Development of histopathological criteria for CN: chained nuclear migration, apoptotic debris, and lamina propria inflammation.
• Clinical and endoscopic data correlation with histopathological findings.

Main Results:

• Thirty-three patients met the criteria for CN.
• Seven cases exhibited MC-like features, while 26 showed inflammatory bowel disease (IBD)-like features (e.g., hematochezia).
• Apoptotic debris was more frequent in IBD-like CN; CD8+ intraepithelial lymphocytes were similar in both groups. PPI use and cessation effects were noted. CN features were also seen in ulcerative colitis remission.

Conclusions:

• Colitis nucleomigrans (CN) is proposed as a distinct clinicopathological entity.
• CN presents with varied clinical and endoscopic findings, ranging from MC-like to IBD-like features.
• Further research is needed to understand the pathogenesis and clinical significance of CN.