Pathology of inflammatory bowel diseases (IBD): variability with time and treatment.

The diagnosis of chronic idiopathic IBD and the differential diagnosis between Crohn's disease and ulcerative colitis can be made in most cases on cumulative clinical, radiological, endoscopical, biochemical and pathological evidence. Diagnostic difficulties can however, occur in fulminant colitis, in early onset disease and in long-standing disease. The microscopic evaluation of disease activity is based on the presence of active inflammation. Effective medical treatment has however, an influence upon the morphology and the evolution of the lesions and hence can affect the diagnostic features and the microscopic features used for the assessment of disease activity. A literature review was performed on clinical drug trials in IBD and the effect of the drugs upon the microscopic features. Several studies have shown that the diagnostic microscopic features and the features characteristic for disease activity vary with time and treatment. For an adequate analysis of biopsy samples of patients with IBD the pathologist should be aware of the duration of the symptoms and the type of treatment given to the patient.