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Findings:

1. AP x-ray of abdomen - linear collection of air within the wall of the ascending colon, extending to the proximal transverse colon.
2. CT of abdomen - corresponds with plain film findings.

Diagnosis: Pneumatosis intestinalis.

Discussion: Pneumatosis intestinalis (PI) is described in two forms, primary (idiopathic), and secondary. Primary PI, approximately 15% of cases is a benign condition. No other respiratory or gastrointestinal abnormality is present. Large well-defined non-communicating round or oval cysts are present in the descending colon with normal mucosa. The patient is usually asymptomatic and the condition usually resolves spontaneously.

Secondary PI, 85% of cases, more commonly involves the small bowel or ascending colon and is associated with a wide variety of pre-existing disorders which cause increased intraluminal pressure and/or disrupt the intestinal mucosa integrity. Examples of causative disorders are intestinal trauma, ischemia or infarction, obstruction, infection or inflammation and chronic obstructive bronchopulmonary disease. Linear segmental gas collections are present within the bowel wall which can narrow the lumen but rarely cause mechanical obstruction. Treatment of the underlying disease leads to resolution of pneumatosis intestinalis.

Primary PI is a diagnosis of exclusion. Patients receiving steroids, immunosuppressive agents or chemotherapy may have very few symptoms even when bowel necrosis is present.

References:
Margulis A, Burhenne H. Alimentary Tract Radiology 4th Edition, 1989.
Chapter 13:296-298.

Eisenberg R. Gastrointestinal Radiology, 2nd Edition. 1989, Chapter 69:881-891.

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