Case Report #0492

1. Radiological Category: Gastrointestinal Principal Modality (1): Principal Modality (2): General Radiography CT Case Report #0492 Submitted by: Paul D. Bertolino, M.D. Faculty reviewer: Venkateswar Surabhi, M.D. Date accepted: 10 March 2008

2. Case History A sixty-one year old man presenting with lower abdominal pain. Patient also complained of nausea, vomiting, fevers and diarrhea.

3. Radiological Presentations

4. Test Your Diagnosis Which one of the following is your choice for the appropriate diagnosis? After your selection, go to next page. • Distal colonic obstruction • Idiopathic Pneumatosis Intestinalis • Ileus • Bowel Infarction Leading to Pneumatosis Intestinalis

5. Findings and Differentials Findings: Linear collections of air are seen outlining the lateral wall of the cecum and ascending colon. Air distends the entire visualized colon. Differentials: • Distal colonic obstruction • Idiopathic Pneumatosis Intestinalis • Ileus • Bowel Infarction Leading to Pneumatosis Intestinalis

6. Pneumatosis intestinalis (PI) is the presence of gas within the bowel wall. Two main theories have been suggested to explain the pathogenesis of this finding: 1) Due to increased intraluminal pressure, air may dissect into the bowel wall from the bowel lumen or from increased pulmonary pressures via the mediastinum. 2) Gas forming bacteria may enter the bowel wall via breaks in the mucosa or through a mucosa with increased permeability. The diagnosis is usually made on conventional radiographs or CT, with CT being more sensitive. The list of conditions associated with PI is extensive, both benign and life threatening in nature. Life threatening conditions include bowel ischemia, intestinal obstruction, colitis, toxic megacolon, trauma and organ transplantation. Benign conditions include pulmonary conditions such as emphysema, asthma, pulmonary fibrosis and cystic fibrosis. Iatrogenic benign causes include barium enemas, endoscopy and postsurgical bowel anastamosis. Other benign conditions include medications (such as corticosteroids or chemotherapeutic agents), peptic ulcers, ileus, collagen vascular disease (especially scleroderma) and diverticulitis. Approximately 15% of cases are considered idiopathic. These cases typically involve the colon, as in the patient presented here. This patient’s past medical history included hypothyroidism, hypertension and seizure disorder. His medication list did not include any that are linked to PI. Because of peritoneal signs on examination, the patient was taken to Discussion

7. the operating room where an exploratory laparotomy was performed and pneumatosis of the right colon was confirmed. No evidence of bowel ischemia or infarction was found in the small or large bowel, and there was no free fluid in the abdomen. Because of the above clinical findings and clinical history, this patient’s PI was thought to be idiopathic in nature. Contrast en- hanced CT through the abdomen demon- strates linear collections of air in the wall of the ascending colon without wall thickening. Incidental imaging of the lung bases did not demonstrate any changes of emphysema. Discussion

8. Another AP view of the abdomen also demonstrates linear collections of air in the region of the wall of the cecum, consistent with pneumatosis intestin- alis. Lung windows can often facilitate the detection of pneumatosis in- testinalis as depicted above. Discussion

9. Idiopathic pneumatosis intestinalis of the colon.1. Bert Lincoln Pear. Pneumatosis Intestinalis: A Review. Radiology 1998 207: 13-19.Shawn D. St. Peter, Maher A. Abbas, Keith A. Kelly. The Spectrum of Pneumatosis Intestinalis. Archives of Surgery 2003 138: 68-75.2. Peter Feczko, Duane Mezwa, Michael Farah, Brian White. Clinical Significance of Pneumatosis of the Bowel Wall. Radiographics 1992 12:1069-1078.3. Lisa Ho, Erik Paulson, William Thompson. Pneumatosis Intestinalis in the Adult: Benign to Life-Threatening Causes. American Journal of Roentgenology. 2007 188: 1604-1613. Diagnosis