Colocolic intussusception in the hepatic flexure and proximal
transverse colon with a 2.5 cm lipoma.
CT (Figures 1-4) revealed the classic “bowel within bowel” configuration
with intervening mesenteric vessels in the region of the proximal
transverse colon (right hypochondrium of the patient) over a segment of
approximately 8 cm with a 2.5 cm rounded fat density lesion at its apex
(Hounsfield unit values of -60 to -130). The intervening bowel layers
showed normal wall enhancement. There was no dilatation of the proximal
bowel. The solid abdominal organs were normal. There was no ascitis.
Corresponding ultrasound images (Figures 5 and 6) showed the
classical pseudokidney appearance of intussusception and a rounded
echogenic lipoma at the apex. The bowel was prepared prior to
surgery and a supraumbilical laparotomy was performed. The
intussusception was reduced and the involved segment at the hepatic
flexure was resected. Biopsy of the resected segment revealed a lipoma
of the hepatic flexure.
Intussusception can be classified according to location or underlying
etiology. It occurs either in the small bowel or the colon. The
underlying etiology is neoplastic (benign or malignant), non-neoplastic
or idiopathic. About 80% to 90% of intussusceptions in adults are
secondary to an underlying pathology, with approximately 65% due to
benign or malignant neoplasm. Non-neoplastic processes constitute 15% to
25% of cases, while idiopathic or primary intussusceptions account for
about 10%. Intussusception arises in the small bowel in two-thirds of
Lipomas are the second most common benign
tumors of the colon after adenomas. These tumors are composed of
well-defined adipose tissue with a clearly demarcated fibrous support
structure. They have a submucous location in 90% of cases. Lipomas can
be located anywhere along the digestive tract but they are most common
in the colon. Within the colon, 50% are found in the caecum and
ascending colon. The occurrence of distal-colon lipoma is rare. Sigmoid
lipoma is extremely rare.3
Intussusception can be
confidently diagnosed on CT because of its virtually pathognomonic
appearance. It appears as a complex soft-tissue mass, consisting of the
outer intussuscipiens and the central intussusceptum. There is often an
eccentric area of fat density within the mass representing the
intussuscepted mesenteric fat, and the mesenteric vessels are often
visible within it. A rim of orally administered contrast medium is
sometimes seen encircling the intussusceptum, representing coating of
the opposing walls of the intussusceptum and the intussuscipiens. The
intussusception will appear as a sausage-shaped mass when the CT beam is
parallel to its longitudinal axis, but will appear as a “target” mass
when the beam is perpendicular to the longitudinal axis of the
intussusception. While the appearance of intussusception is
characteristic on CT, its etiology cannot usually be established.
Exceptions are lipoma, a long intestinal tube and known abdominal
metastatic disease. A lipoma serving as a lead point is identified as a
mass of fat density that does not contain blood vessels. Mesenteric fat
entrapped in an intussusception also has fat density but has blood
vessels coursing through it, and can thus be distinguished from lipoma.4
and Lee found that intussusceptions seen on CT that had a neoplastic
lead point were significantly longer and had a significantly larger
diameter than non-neoplastic ones.5 They also found proximal
dilatation of the small bowel to be significantly more common in
intussusceptions with a neoplastic lead point.
The bowel loops
proximal to the intussusception are usually of normal calibre and are
occasionally dilated, since intussusception in adults only rarely
presents as intestinal obstruction.6 Although intussusception
in adults may be diagnosed by many other imaging modalities, including
barium enema, upper gastrointestinal series and ultrasound, CT is
clearly superior. In contrast to ultrasound, CT is not affected by the
presence of gas in the bowel and will clearly demonstrate the
intussusception, whether in the small bowel or in the colon. Additional
valuable information such as the presence of metastatic disease or
lymphadenopathy is readily obtained by CT and may point to an underlying
Ultrasound imaging of this condition demonstrates
several unique appearances: on a transverse section one can see a
“doughnut” shape and on a longitiudinal section one can see a “bull’s
eye” confirguation, and a pseudokidney finding is also typical.
findings also permit a presurgical evaluation of the degree of vascular
involvement caused by intussusception. The presence of gas within the
intussusceptum suggests perforation or gangrene, indicating the need for
an emergency operation.
In this patient, spiral CT showed a
lipoma situated in the proximal transverse colon, causing colocolic
intussusception. The CT study helped to determine the viability of the
intussuscepted loop prior to surgery, thus reducing the extent of
surgical treatment and only the tumor was removed. Multiplanar
reconstructed spiral CT, allowed examination of the intussusception and
lipoma from various angles.
CT is a valuable tool in cases of intussusception due to colonic lipoma.
The most important factor for establishing the diagnosis is awareness
of the possibility of intussusception occurring in an adult patient with
abdominal symptoms, CT is then the examination of choice.
- Agha FP. Intussusception in adults.AJR Am J
- Begos DG, Sandor A, Modlin IM. The diagnosis and management of
adult intussusception. Am J Surg. 1997;173:88-94.
- Zeebregts CJ, Geraedts AA, Blaauwgeers JL, Hoitsma HF.
Intussusception of the sigmoid colon because of an intramuscular
lipoma. Dis Colon Rectum.1995:38:891-892.
- Gayer G, Zissin R, Apter S, et al. Pictorial review: Adult
intussusception-A CT diagnosis. Br J Radiol.
- Warshauer DM, Lee JK. Adult intussusception detected at CT or
MR imaging: Clinical imaging correlation. Radiology.
1999;212: 853-860. 6 Gayer G, Apter S, Hofmann C, et al.
Intussusception in adults: CT diagnosis. Clin Radiol.