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
<
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