ABSTRACT
Colorectal biopsy finds a unique role in the diagnosis of lymphocytic and collagenous colitis, the two main conditions within the spectrum of disease commonly referred to as microscopic colitis. This latter term, as used in this book, will by definition incorporate both conditions. The majority of patients within this spectrum have chronic watery diarrhoea, a string of normal laboratory tests and,
significantly, a normal or near-normal colonoscopic examination. The diagnosis depends entirely on the taking of a biopsy, which itself depends on a clinician appreciating that a normal-appearing colonic mucosal surface does not necessarily indicate normal microscopy. Variability in clinical awareness on this issue may account for the large range in reporting incidence between centres (Kitchen et al., 2002).
