Colonic Crohn’s disease

Colonic Crohn’s disease

Colonic involvement is found in 30% of patients with CD, frequently in association with perianal disease, and may coexist with small bowel pathology . Colonic CD presents with symptoms of colitis and proctitis as described for UC, although toxic megacolon is much less common. Colonic strictures may form just as are seen in small bowel CD. Endoscopic dilatation may be performed in expert hands as an alternative to surgical resection. Distinguishing between CD and UC is often di ffi cult and requires clinical and pathological patterns to be combined. The presence of skip lesions, rectal sparing, non-caseating granulomas or perianal disease will point to CD ( Figure 75.12 ). Many patients with CD present with perianal problems. In the presence of active disease, the perianal skin can have a bluish tinge. Large, oedematous and inflamed skin tags are common. Fissures and superficial ulcers with undermined edges are rela tively painless and can heal with bridging of epi - - thelium. Deep cavitating ulcers are usually found in the upper - anal canal; they can be painful and cause perianal abscesses and fistulae. Fistulation through the posterior wall of the vagina may lead to rectovaginal fistula and contin uous leakage of gas and/or faeces per vagina (see Chapter 80 ).

The rectal mucosa is often spared in CD and will feel nor mal on rectal examination. If involved, it may feel thickened, nodular and irregular. Severe CD proctitis may occasionally be mistaken for cancer. Perianal disease is frequently associ ated with dense, fibrous stricturing (stenosis) at the anor junction. Incontinence may develop because of destruction of the anal sphincter musculature owing to inflammation, abscess formation, fibrosis and repeated sur gical drainage. In severe cases, the perineum may become densely fibrotic, rigid and covered with multiple discharging openings (watering-can perineum). Each patient with CD should have their disease phenotype (manifestations) classified according to the Montreal classifica tion ( Table 75.3 ). This is important as it allows an overview of disease progression in the individual patient ov er time, and enables group comparisons and evaluations. The Montr classification specifies age at diagnosis, behaviour and disease location.

Figure 75.12 Colonic Crohn’s disease. Note the normal mucosa on either side of the in /f_l ammatory stricture (courtesy of Professor Brian Warren, John Radcliffe Hospital, Oxford, UK).