Pneumatosis intestinalis of the sigmoid colon secondary to repetitive injury to the rectum from the insertion of foreign bodies

By Josethy Solorzano , MD, Shweta Bhatt, MD, and Vikram S Dogra, MD
Diagnosis
Pneumatosis intestinalis of the sigmoid colon secondary to repetitive injury to the rectum from the insertion of foreign bodies </<span class="end-tag" />P
Findings
An abdominal radiograph was taken that revealed 2 linear foreign bodies (pens) in the rectosigmoid region (Figure 1). The pens were removed with the help of sigmoidoscopy. CT of the abdomen and pelvis was performed to evaluate for rectosigmoid injury. An axial CT image through the pelvis (in a lung window display) revealed the presence of multiple air-&#64257;lled cystic areas arising from the inner wall of the sigmoid colon and protruding into the bowel lumen. These &#64257;ndings were suggestive of pneumatosis intestinalis (also known as pneumatosis cystoides) involving the rectosigmoid and distal sigmoid colon. (Figure 2). </<span class="end-tag" />P
Discussion
Pneumatosis (cystoides) intestinalis (PI) is de&#64257;ned as multiple gas-&#64257;lled cysts in the gastrointestinal tract wall.<Sup>1-3 </<span class="end-tag" />Sup>The cysts may be located in the subserosa, submucosa, and, rarely, the muscularis layer.<Sup>1,4 </<span class="end-tag" />Sup>They may be single or multiple and vary in size from microscopic to several centimeters in diameter.<Sup>4 </<span class="end-tag" />Sup>They are usually lined by mixed in&#64258;ammatory cells, macrophages, or foreign body giant cells<Sup>1,3,4 </<span class="end-tag" />Sup>with no communication between the air spaces and the bowel lumen.<Sup>5,6 </<span class="end-tag" />Sup>However, PI is a radiographic &#64257;nding and not a diagnosis. PI is considered an ominous &#64257;nding in ischemia, particularly if it is associated with portomesenteric venous gas.<Sup>1,6 </<span class="end-tag" />Sup>The majority of cases of PI occur in the jejunum and ileum, with 6% to 10% of cases involving the colon.<Sup>6 </<span class="end-tag" />Sup></<span class="end-tag" />P
><P

>Two forms of PI have been recognized: primary and secondary.<Sup>4,5,7,8 </<span class="end-tag" />Sup>Primary pneumatosis intestinalis (15% of cases) is a benign idiopathic condition, and patients are usually asymptomatic. These cysts are incidentally discovered on radiography or endoscopy. The secondary form (85% of cases) is associated with obstructive pulmonary disease, as well as obstructive and necrotic gastrointestinal diseases.<Sup>6,8 </<span class="end-tag" />Sup></<span class="end-tag" />P
><P

>Although the exact prevalence is unknown, PI is a rare condition. No sex or race predominance has been reported.<Sup>6 </<span class="end-tag" />Sup>The exact pathogenesis of PI is not known and many theories explaining the process have been put forth. The most prominent theories are mechanical, bacterial, and pulmonary mechanisms.<Sup>7,8 </<span class="end-tag" />Sup>More than 50 causative factors have been identi&#64257;ed that result in PI.<Sup>1,7 </<span class="end-tag" />Sup>The breadth of pathologic conditions associated with PI formation suggests that its development is a multifaceted phenomenon.<Sup>2 </<span class="end-tag" />Sup>Common causes are summarized in Table 1. </<span class="end-tag" />P
><P

>Plain X-ray &#64257;lm &#64257;ndings of PI include air within the walls of the gastrointestinal tract. The patterns of the radiolucencies seen may be linear, curvilinear, small bubbles, or collections of larger cysts.<Sup>5,7 </<span class="end-tag" />Sup>Pneumoperitoneum or pneumoretroperitoneum can be seen secondary to cyst rupture.<Sup>6-9 </<span class="end-tag" />Sup></<span class="end-tag" />P
><P

>On barium enema, PI is visualized as a circumscribed attenuation pattern in the contrast column. When the cysts protrude into the lumen, they may mimic polyps or carcinomas on barium enema studies.<Sup>2,3,7,8 </<span class="end-tag" />Sup>Gas enters the bowel wall because of direct trauma. Enhanced gut permeability to gas can be induced by defects in the mucosa, the gut&rsquo;s immune barrier (intramural lymphoid tissue), or both.<Sup>2 </<span class="end-tag" />Sup>The current case is interesting because it is the &#64257;rst published reported patient with PI after direct repetitive colon trauma. </<span class="end-tag" />P
><P

>On ultrasound, the appearance of PI includes circumferential, bright, echogenic foci in the bowel wall. Computed tomography (CT) with a wide lung parenchyma window is the best imaging modality for establishing the diagnosis of PI. It has greater sensitivity than plain &#64257;lm or ultra-sound.<Sup>6,7 </<span class="end-tag" />Sup>CT can distinguish PI from intraluminal air or submucosal fat. A thickened bowel wall with contrast enhancement may suggest ischemia in the setting of PI. Dilated bowel loops and abnormal &#64258;uid levels suggest an obstructive cause. </<span class="end-tag" />P
><P

>When a foreign body causes PI, a careful history and physical examination should be followed by a biplanar radiograph of the abdomen to determine the exact position of the foreign body (or bodies) and to assess the presence of free air to exclude perforation.<Sup>10 </<span class="end-tag" />Sup>The most common reason for rectal foreign bodies is autoeroticism; other causes include criminal assault and medical diagnostic indications.<Sup>10 </<span class="end-tag" />Sup></<span class="end-tag" />P
><p><B>CONCLUSION </<span class="end-tag" />B></<span class="end-tag" />p><P

>Usually a benign condition, PI may be detected on various imaging modalities. It has a unique presentation when con&#64257;ned to the colon, with air cysts lining the inner wall. The presence of PI in the small bowel is considered an ominous &#64257;nding in ischemia, particularly if it isassociated with portomesenteric venous gas. </<span class="end-tag" />P
><P <OL
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Pneumatosis intestinalis of the sigmoid colon secondary to repetitive injury to the rectum from the insertion of foreign bodies.  Appl Radiol. 

August 03, 2007
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