PNEUMATOSIS COLI - A PROPOSED PATHOGENESIS BASED ON STUDY OF 25 CASESAND REVIEW OF THE LITERATURE

Pneumatosis coli is a rare condition characterised by multiple gas-fil led cysts within the bowel wall. We present 25 cases treated over the past 30 years. The patients' mean age was 59 years: 15 were female. Pr esenting symptoms included diarrhoea (n=17), mucus discharge (n=17), r ectal bleeding (n=15) and constipation (n=12). Pneumatosis usually aff ected the left colon (96%), and diagnosis was by sigmoidoscopy and bio psy in 18 cases (72%). Pneumatosis coli was associated with psychiatri c disorders (36%), chronic lung disease (20%) and colitis (12%). A red undant sigmoid colon was observed in 80% of cases on contrast radiolog y. Five patients had mucosal pseudolipomatosis on histological examina tion. Histological and immunohistochemical review indicated that the c ysts were lined by cells of macrophage/monocyte phenotype and that man y similar mononuclear cells were present in the adjacent submucosa and overlying mucosa. Treatment with antidiarrhoeals and anti-inflammator y drugs in 14 patients resulted in improvement in 9 cases (64%). Oxyge n therapy (n=9) always alleviated symptoms. There was a high recurrenc e rate (50-78%), but with further courses of therapy lasting remission was achieved in five patients. Two patients underwent colectomy. The associations of pneumatosis coli with psychiatric disorders and mucosa l pseudolipomatosis are new and of possible pathogenetic significance. A novel pathogenetic mechanism is suggested to explain the associatio n of pneumatosis coli and chronic respiratory disorders. A model of pn eumatosis coli linking some of the apparently disparate pathogenetic t heories is proposed.