Pneumatosis cystoides coli is characterized by the presence of multiple gas-containing cysts in the colon wall. The gas content of the cysts is mainly nitrogen. The cause of the condition is uncertain, although some patients have coexistent chronic obstructive pulmonary disease. Occasionally, the pneumatosis is associated with underlying inflammatory bowel disease or ischemic colitis. Film .3 illustrates very gross pneumatosis cystoides with almost total obliteration of the lumen of the ascending colon (arrows) by the massive gas cysts, in a patient with long-standing Crohn's disease. As in both the above cases, pneumatosis cystoides is usually segmental in distribution. On plain abdominal radiographs, the clusters of gas-containing cysts often produce a "bunch of grapes" appearance. Film .4 shows the typical appearance of these cystic gas collections in the region of the descending colon. These can be contrasted with the normal appearance of colonic gas in the right colon.
Patients with this condition may be symptomless or have a variety of complaints including diarrhea, rectal bleeding or lower abdominal pain. Symptomatic cases have been successfully treated with hyperbaric or other forms of oxygen therapy, which promote resorption of nitrogen from the cysts.