Atypical perinuclear antineutrophil cytoplasmic antibodies in patients with Crohn's disease

Atypical perinuclear antineutrophil cytoplasmic antibodies (p-ANCA) occur inmost patients with ulcerative colitis but only in a minority of those with Crohn's disease,:ln a recent study from the United States,:this serological marker was reported to be present in 100% of Crohn's disease patients with a clinical phenotype of 'left-sided ulcerative colitis' but was not present: in patients with 'isolated' small bowel disease. In a previously reported survey from the author's hospital, the p-ANCA status of 247 consecutive patients with Crohn's:disease was evaluated, and, of these, 33 Crohn's disease patients were seropositive, including 18 (13.0%) with combined small and large bowel disease, 11 (19.6%) with 'isolated' colorectal disease, and four (4.6%) with 'isolated' small bowel but no detectable colorectal disease. To further evaluate and verify the significance of atypical p-ANCA in these 33 patients, clinical; radiological, endoscopic and histological features were examined. This study confirms that an 'ulcerative colitis-like' clinical phenotype may be seen in most, but not all, serologically positive Crohn's disease patients. Moreover, 'isolated' small bowel disease in the absence of ii colorectal disease occurs. Detection of atypical p-ANCA in Crohn's disease with different clinical and pathological features provides serological evidence that Crohn's disease is a very heterogeneous disorder.