Clinical and endoscopic features of amyloidosis secondary to Crohn's disease: diagnostic value of duodenal observation and biopsy.

Aim: Recent reports have focused on the development of secondary amyloidosis (AMY) as a complication of Crohn's disease (CD). The present study was carried out to investigate the frequency of AMY secondary to CD, its clinical and endoscopic features, and the importance of duodenal biopsy in detecting this disease. Methods: This study involved 408 patients diagnosed with CD who were endoscopically and histologically examined at our hospital. At follow up, we analyzed the incidence of AMY complications, the clinical features of AMY and the methods to diagnose AMY. Results: The incidence of AMY was 2.5% (10/408). The disease type at the time of CD diagnosis was small and large bowel type (SL) in eight patients, small bowel type in one and large bowel type in one. The incidence of AMY was significantly higher in patients with SL than in patients with other disease types. The length of time from onset of CD to diagnosis of AMY was 14.1 +/- 8.0 years. The cumulative incidence of AMY was 1.0% at 10 years and 5.7% at 20 years after onset. In terms of the method used to diagnose AMY, the positive rate of AMY diagnosis was 100% with endoscopic duodenal biopsy. Conclusion: The incidence of AMY as a complication of CD was low (2.5%). However, because this complication adversely affects patients' prognoses, it is important to check for the presence of AMY, particularly in the duodenum, in patients for whom more than 10 years have elapsed since the development of CD.