Chapter 16 INFLAMMATORY BOWEL DISEASE
INFLAMMATORY BOWEL DISEASE
Crohn’s disease and ulcerative colitis are types of inflammatory bowel disease (IBD) characterised by inflammation leading to a disturbance of gut function and, to a greater or lesser degree, systemic symptoms. Therapy is empirical. Many patients require emotional support and contact with patient support groups is often very helpful. Although these conditions are sometimes hard to differentiate, there are sufficient differences between them to indicate distinct pathological processes. Some of these differences are listed in Table 16.1.
Crohn’s disease | Ulcerative colitis | |
---|---|---|
Genetics | Identified susceptibility gene(s) | Weaker association |
Distribution | Anywhere in the gut | Exclusively colonic |
Perianal disease | Common | Uncommon |
Pathology |
ULCERATIVE COLITIS
The extraintestinal manifestations of UC may affect the skin, joints, eyes and/or the liver (Table 16.2). These may occur before, during or after the onset of gut symptoms and may be associated with disease activity. These are generally more common in UC than Crohn’s disease.
Skin | Erythema nodosum |
Pyoderma gangrenosum | |
Aphthous stomatitis | |
Joints | Type 1 peripheral osteopathy* |
Type 2 arthritis** | |
Sacroileitis | |
Eyes | Iritis |
Uveitis | |
Episcleritis | |
Liver | Primary sclerosing cholangitis |
* Acute self-limiting inflammation affecting <5 joints, lasting <5 weeks and associated with symptom relapse and with other extraintestinal manifestations.
** Chronic arthritis affecting five or more joints with a median duration of symptoms of 3 years, and associated with uveitis but not erythema nodosum.
The differential diagnosis is considered in Table 16.3.
• Ischaemic colitis, especially in the elderly with evidence of widespread atherosclerosis or cardiac dysrhythmias, in particular atrial fibrillation |
Ulcerative colitis can generally be differentiated from Crohn’s disease using endoscopic and pathological criteria (Table 16.1). UC affects the colon exclusively and almost always involves the rectum from which it extends proximally in continuity. Sigmoidoscopy will show evidence of proctitis although occasionally patients can have ‘rectal sparing’, particularly if there has been use of corticosteroid or 5-aminosalicylate enemas. Biopsies will show that the inflammation involves the more superficial layers of the mucosa, macrophages are less common and granulomata are not present. Sigmoidoscopic biopsies will help differentiate between UC and other causes of colitis, such as ischaemic colitis and radiation colitis.
Acute self-limited colitis
Some patients present with symptoms suggestive of UC, have no causative organisms grown on culture, resolve spontaneously and never have a subsequent attack. About one-half to two-thirds of patients with ‘self-limited’ colitis will develop recurrent symptoms characteristic of ulcerative colitis. The diagnosis of ulcerative colitis may be suspected after the initial presentation but is only confirmed after a subsequent attack.