Clinicopathological significance of lymphocytic colitis/collagenous colitis in inflammatory bowel disease.

Patients with inflammatory bowel disease (IBD) may occasionally present with lymphocytic colitis/collagenous colitis (LC/CC) either before or after the onset of IBD. Although a few reports have described a small number of such cases, the relationship between these 2 disorders is still unclear. We evaluated 27 patients with diagnosis of either ulcerative colitis (UC) or Crohn disease (CD) and LC/CC. Clinical, endoscopic, and pathological features were reviewed. Ten patients with initial diagnoses of LC (n = 2)/CC (n = 8) evolved into UC (n = 7) or CD (n = 3) after a median interval of 14 months (range, 2-44 months). Among these, 4 patients with LC/CC evolving into IBD also had recurrent CC in a quiescent phase of IBD. Seventeen patients with initial diagnosis of UC (n = 11) or CD (n = 6) developed LC (n = 6)/CC (n = 11) after a median interval of 108 months (range, 15-548 months). IBD patients with initial presentation of LC/CC were significantly older than those who developed LC/CC after onset of IBD (66.5 versus 34.0 years old, P = .001). The interval time between LC/CC to IBD was significantly shorter than that of IBD to LC/CC (14 versus 108 months, P = .007). Quiescent UC with superimposed CC was the most common pattern (n = 8). Patients with CD had shorter interval time to develop LC/CC than UC patients, although it was not statistically significant (60.5 versus 139 months, P = .14). Endoscopically, most patients that started with LC/CC had unremarkable findings, but 11 of 17 patients who developed LC/CC after IBD showed quiescent chronic colitis. Histologically, LC/CC patients with diagnosis of IBD, either before or after, more frequently show active inflammation. Chronicity was more commonly seen in biopsy of LC/CC patients with a history of IBD. Our study found that IBD patients with initial presentation of LC/CC tend to occur in older age, with shorter interval time and frequent active inflammation in initial LC/CC. These findings suggest that LC/CC may be a spectrum of IBD as the initial presentation in a subset of older IBD patients. On the other hand, IBD patients can develop LC/CC associated with chronic mucosal injury many years after the onset of IBD (typically with >10 years interval time while patients are in remission phase), for which these 2 processes seem unrelated to each other.