IBD and related diagnostically difficult entities of the colon

Abstract

This lecture (review) summarises current diagnostic problems and advances with regard to patterns of inflammation and dysplasia in inflammatory bowel disease (IBD), particularly ulcerative colitis and Crohn’s disease. In a small percentage of cases, a definite diagnosis of ulcerative colitis or Crohn’s disease cannot be established in which the term ‘indeterminate colitis’ has been used. Most cases of indeterminate colitis are related to fulminant colitis, a condition in which the classic features of ulcerative colitis or Crohn’s disease may be obscured by severe ulceration with early fissuring ulceration, transmural inflammation, and relative rectal sparing. Several studies suggest that ileal/anal pouch anastomosis procedure is safe and effective in patients with indeterminate (fulminant) colitis. In biopsy studies, there are a number of exceptions to the classic principles in IBD pathology that may lead to diagnostic confusion and simulate Crohn’s-like tissue reactions in patients with ulcerative colitis. For instance, skip lesions may occur in patients with ulcerative colitis in the follow settings: long-term oral or topical therapy, and on initial presentation in paediatric patients. Patients with IBD are at increased risk for the development of dysplasia and carcinoma. Dysplasia in IBD is classified as flat or elevated, and then microscopically as negative, indefinite, low or high grade. In addition to the conventional (intestinal) type of dysplasia, other less common and more diagnostically difficult types of dysplasia, such as serrated dysplasia and mucinous hypervillous epithelium, may occur in some patients with IBD. There is recent evidence to suggest that patients with flat low grade dysplasia should also be considered strongly for colectomy. Elevated lesions in IBD (DALM) are subdivided into adenoma-like and non-adenoma-like based on their endoscopic appearance. Regardless of the grade of dysplasia, adenoma-like lesions may be treated adequately by polypectomy if there are no other areas of flat dysplasia in the patient. The surveillance and treatment options for patients with flat and elevated dysplasia in IBD will be reviewed in detail.