Adult Intestinal Intussusception.docx

Adult Intestinal Intussusception: CT Appearances and Identification of a Causative Lead Point Young H. Kim, Michael A. Blake, Mukesh G. Harisinghani, Krystal Archer-Arroyo, Peter F. Hahn, Martha B. Pitman, Peter R. Mueller Author Affiliations Published Online:May 1 2006https://doi.org/10.1148/rg.263055100 Sections PDF Tools Share

Abstract The widespread application of computed tomography (CT) in different clinical situations has increased the detection of intussusception, particularly non–lead point intussusception, which tends to be transient. Consequently, determining the clinical significance of intussusception seen at CT poses a diagnostic challenge. Patients with intussusception may or may not be symptomatic, and symptoms can be acute, intermittent, or chronic, making clinical diagnosis difficult. In most cases, radiologists can readily make the correct diagnosis of intestinal intussusception by noting the typical bowelwithin-bowel appearance at abdominal CT. However, the CT findings that help differentiate between lead point and non–lead point intussusception have not been well studied. Nevertheless, although there is considerable overlap of CT findings, when a lead mass is seen at CT as a separate and distinct entity vis-à-vis edematous bowel, it can be considered a reliable indicator of a lead point intussusception. Differentiating between lead point and non–lead point intussusception is important in determining the appropriate treatment and has the potential to reduce the prevalence of unnecessary surgery. © RSNA, 2006

LEARNING OBJECTIVES FOR TEST 2 After reading this article and taking the test, the reader will be able to: • Describe the CT appearances of adult intestinal intussusception. . • List the clinical manifestations of adult intestinal intussusception. .

• Discuss the CT findings that can help differentiate between intussusception w . intussusception without a lead point.

Introduction Approximately 5% of all intussusceptions occur in adults, accounting for 1% of all bowel obstructions (,1). It has often been stated that intestinal intussusception in adults is frequently caused by serious underlying disease, with 70%–90% of cases having a demonstrable cause based on discharge diagnosis or surgical results (,1,,2). The growing use of computed tomography (CT) for abdominal imaging has led to increased detection of transient intussusceptions with no underlying disease. Consequently, determining the clinical significance of intussusception detected with CT poses a fresh diagnostic challenge. In this article, we review the pathophysiologic features and classification of intussusception. We also discuss and illustrate the clinical and CT manifestations of lead point versus non– lead point intussusceptions and of small bowel versus large bowel intussusceptions.

Pathophysiologic Features of Intussusception Intussusception is the invagination of a bowel loop with its mesenteric fold (intussusceptum) into the lumen of a contiguous portion of bowel (intussuscipiens) as a result of peristalsis. Intraluminal polypoid lesions have a greater tendency to cause invagination of the bowel as

peristalsis drags the lesion forward. Although the exact mechanism precipitating intussusception, especially intussusception without a lead point, is not well understood, this condition has been ascribed to dysrhythmic contractions.

Classification of Intussusception Intussusceptions are classified according to location (enteroenteric, ileocolic, ileocecal, or colocolic) and cause (benign, malignant, or idiopathic). Intussusception in an adult can be further classified on the basis of whether a lead point is present (,Table 1). Intussusception without a lead point tends to be transient. Although an intussusception with a lead point tends to be persistent or recurrent, it can also be transient. Transient nonobstructing intussusception without a lead point is known to occur in both adults and children and occurs more frequently than was previously reported (,3–,5). Transient intussusception of the small bowel has been reported in adults with celiac disease (,2) and Crohn disease (,6) but is most frequently detected incidentally and is presumed to be innocuous. On rare occasions, transient tumor-related colocolic intussusception can occur (,7).

Manifestations of Intussusception Intussusception without a Lead Point Intussusception without a lead point may manifest as vague abdominal pain; however, most cases are discovered incidentally at CT performed for other reasons. An intussusception without a lead point does not generally cause proximal bowel obstruction (,8). It typically appears as a targetlike or sausage-shaped mass, depending on the axial projection (,9). Distinct anatomic features, including the entering wall, mesenteric fat and vessels, returning wall, and intraluminal space, can be clearly seen at CT (,Figs 1, ,2). At abdominal CT, the presence of a bowel-within-bowel configuration with or without mesenteric fat and mesenteric vessels is pathognomonic for intussusception (,Fig 3,,).

Intussusception with a Lead Point Intussusception with a lead point may manifest with atypical clinical

findings. Often, there is a prior history of episodic crampy abdominal pain, nausea, and vomiting, symptoms that suggest partial intestinal obstruction (,9,,10). Intussusception with a lead point can also manifest with symptoms related to a neoplastic process, including constipation, weight loss, melena, or a palpable abdominal mass at physical examination, rather than specific symptoms related to the intussusception itself. Symptomatic diagnosis of intussusception with a lead point is difficult owing to the variety of clinical manifestations. The presence of a lead point, the configuration of the lead mass, the degree of bowel wall edema, and the amount of invaginated mesenteric fat all affect the appearance of an intussusception. If there is bowel wall edema due to impaired circulation of the mesenteric vessels, thickened bowel loops make it difficult to differentiate a lead mass from inflammation because the former may appear amorphous (,Fig 4,). An intussusception with a lead point appears as an abnormal targetlike mass with a cross-sectional diameter greater than that of the normal bowel and may be associated with proximal bowel obstruction. Identification of a lead mass that is separate and distinct from bowel loops is not easy; however, a mass that is seen at CT can serve as a reliable radiologic indicator of an intussusception with a lead point, even though it is hard to discern the exact underlying disease in most cases. Identification of distinct anatomic features is often challenging due to the complex appearance of both bowel wall edema and the lead mass (,Fig 5). The follow-up of incidentally detected intussusceptions with no known underlying cause has not been clearly defined, and the respective roles of modalities such as interval CT, small bowel follow-through examination, enteroclysis, CT enteroclysis, and wireless capsule endoscopy have yet to be determined (,11).

Small Bowel Intussusception Small bowel intusssuception without a lead point is more common than intussusception with a lead point (,3). Intussusception without a lead point is known to appear as a nonobstructing segment, usually smaller in diameter and shorter than an intussusception with a lead point (,3,,12,,13). A lead point intussusception involving the small bowel is generally due to a benign condition and less often to a neoplasm, which, when it occurs, is usually a metastatic lesion (,10). Such an intussusception involving the colon in an adult is often

related to a primary or secondary malignant neoplasm (,Table 2). If there are findings suggestive of a lead point intussusception (eg, a long, large-caliber segment with proximal bowel obstruction) and a probable identifiable lead mass, surgical treatment should be recommended.

Meckel Diverticulum Meckel diverticulum is the most common congenital anomaly of the gastrointestinal tract, occurring in 2%–3% of the population. Common complications include hemorrhage, small bowel obstruction, and diverticulitis. A Meckel diverticulum may invaginate or invert into the lumen of the small intestine. Once inverted, the diverticulum may serve as a lead point for an ileoileal or ileocolic intussusception (,Fig 6,,) (,14). Typically, an inverted Meckel diverticulum appears at CT as a central core of fat attenuation surrounded by a collar of soft-tissue attenuation. Provided this typical appearance is recognized at CT, the diagnosis can be made prospectively (,15).

Venous Malformations Venous malformations of the gastrointestinal tract may manifest with bleeding, with anemia, or, if they form a mass, with intussusception (,Fig 7,,,) (,16). The cecum is the most common site of venous malformations, followed by the right colon and the jejunum. Patients with venous malformations tend to be elderly with a history of cardiovascular disease. In younger patients, venous malformations tend to occur at atypical sites such as the small bowel (,17).

Inflammatory Fibroid Polyp An inflammatory fibroid polyp of the gastrointestinal tract is a rare polypoid lesion in this location. It is a type of inflammatory pseudotumor or myo-fibroblastic tumor that occurs most commonly in the stomach, followed by the small bowel, but it can be seen throughout the gastrointestinal tract (,Fig 8,) (,18,,19). Inflammatory fibroid polyp has been shown to ulcerate and cause gastrointestinal bleeding and simple mechanical obstruction but rarely manifests with intussusception (,19).

Lymphoma

Primary lymphoma of the gastrointestinal tract accounts for approximately 20%–40% of all malignant tumors in the small bowel (,20,,21). Common presenting symptoms include abdominal pain, weight loss, small bowel obstruction, and acute abdomen. Most T-cell lymphomas manifest as ulcerated plaques or strictures in the proximal small bowel, whereas B-cell lymphomas tend to manifest as annular or polypoid masses in the distal and terminal ileum (,21). CT is increasingly being used for the evaluation of patients with known or suspected gastrointestinal lymphoma, since it allows evaluation of both the mural and extramural components of the disease. CT findings of regional or mesenteric lymphadenopathy associated with a bowel wall mass can help distinguish lymphoma from other bowel diseases. When CT demonstrates mild bowel wall thickening with small lymph nodes, the detection of the underlying cause of intussusception may be difficult because differentiation from bowel wall edema may not be possible (,Fig 9,,).

Metastatic Malignant Fibrous Histiocytoma Malignant fibrous histiocytoma is the most common soft-tissue sarcoma late in life, occurring most commonly in the extremities, trunk, and retroperitoneum and rarely in the visceral organs (,22,,23). Metastatic malignant fibrous histiocytoma can be an unusual cause of small bowel intussusception when it manifests as a polypoid mass (,Fig 10,,,).

Large Bowel Intussusception More than one-half of large bowel intussusceptions are associated with malignant lesions, including primary tumors (adenocarcinoma, lymphoma) and metastatic disease (,1). Associated benign lesions include neoplasms such as lipoma and adenomatous polyp (,8). Colonic intussusception often manifests with abdominal pain due to a recurring intussusception that causes intestinal obstruction (,8). Identification of a lead mass at CT is often possible, although determination of an underlying cause is not easy except in the case of a lipoma, which manifests as a well-marginated mass with fat attenuation. Transient tumor-related colocolic intussusception has been reported (,7).

Ileocolic-Ileocecal Intussusception Melanoma metastases to the gastrointestinal tract are the most common metastatic lesions of the bowel (,Fig 11,,). Small bowel metastases attributed to cutaneous malignant melanoma are found in 2%–5% of patients, with the small bowel being the most frequently involved anatomic structure, followed by the stomach and large bowel. Intussusception caused by metastatic melanoma is very rare (,24). Patients who present with acute complications such as bleeding, perforation, intussusception, and obstruction require urgent surgical intervention (,25).

Colocolic Intussusception Lipoma.— Lipomas are the most common benign cause of colocolic intussusception in adults. Next to adenomatous polyps, these mesenchymal tumors are the most common benign tumors of the colon. Lipomas of the colon are within the submucosa in 90% of cases, are usually solitary, and may be sessile or pedunculated (,26). Lipomas are often discovered incidentally at endoscopic or radiologic examination and can easily be diagnosed with CT due to their typical fat attenuation (,Fig 12). Close observation of consecutive axial images can help avoid misinterpreting entrapped mesentery and subserosal fat as a lipoma. Multiplanar reformation may be used to confirm the diagnosis of intussusception when axial views raise suspicion for such a diagnosis. Lipomas are almost always asymptomatic until they cause abdominal pain, sometimes due to intussusception.

Adenocarcinoma.— Adenocarcinoma of the colon is the most common malignant neoplasm associated with colonic intussusception (,Fig 13,). Typical signs and symptoms of adenocarcinoma of the colon include bleeding, obstruction, a palpable abdominal mass, and abdominal pain. The individual layers of the intussuscepted bowel wall are more easily distinguished from the lead mass in this intussusception. Differentiation of the lead mass from bowel wall edema at CT is generally easier in large bowel intussusception than in small bowel

intussusception due to the greater caliber of the colon.

Conclusions Intussusceptions without a lead point are increasingly being identified at routine CT and pose a diagnostic challenge. Abdominal CT can be helpful in distinguishing between lead point intussusception and non–lead point intussusception and has the potential to reduce the prevalence of unnecessary surgery. Although there is considerable overlap of CT findings, identification of a lead mass that is separate and distinct from edematous bowel can help make this distinction.

Table 1. Clinical Features of Adult Intestinal Intussusception

Table 2. Causes of Adult Intestinal Lead Point Intussusception

Figure 1. Longitudinal (top) and cross-sectional (bottom) diagrams illustrate a typical transient type intussusception, with invagination of a segment of the gastrointestinal tract (intussusceptum) (solid arrows) into an adjacent segment (intussuscipiens) (open arrows). Note also the invagination of the mesentery (M) and mesenteric vessels (arrowheads). (Courtesy of B.I. Choi, MD, Department of Radiology, Seoul National University Hospital, Seoul, South Korea.) Download as PowerPointOpen in Image Viewer

Figure 2. Small bowel intussusception in a 51-year-old man with recurrent left lower quadrant pain. Contrast material–enhanced CT scan of the abdomen demonstrates the typical multilayered appearance of a small bowel intussusception. The intussusceptum (black arrowhead), with an accompanying complex of mesenteric fat and blood vessels (arrow), is surrounded by the thick-walled intussuscipiens (white arrowhead). Download as PowerPointOpen in Image Viewer

Figure 3a. Transient type small bowel intussusception in a 54-yearold woman. Contrast-enhanced CT scans of the abdomen demonstrate the classic findings of a targetlike (arrow in a), sausageshaped (arrow in b and c) mass, findings that are pathognomonic for intussusception. Mesenteric fat and blood vessels are barely visible. Download as PowerPointOpen in Image Viewer

Figure 3b. Transient type small bowel intussusception in a 54-yearold woman. Contrast-enhanced CT scans of the abdomen demonstrate the classic findings of a targetlike (arrow in a), sausageshaped (arrow in b and c) mass, findings that are pathognomonic for intussusception. Mesenteric fat and blood vessels are barely visible. Download as PowerPointOpen in Image Viewer

Figure 3c. Transient type small bowel intussusception in a 54-yearold woman. Contrast-enhanced CT scans of the abdomen demonstrate the classic findings of a targetlike (arrow in a), sausageshaped (arrow in b and c) mass, findings that are pathognomonic for intussusception. Mesenteric fat and blood vessels are barely visible. Download as PowerPointOpen in Image Viewer

Figure 4a. Transient type small bowel intussusception in a 49-yearold man with abdominal pain who had suffered a fall. (a) Contrastenhanced CT scan demonstrates an amorphous mass (arrow) that is due to bowel wall edema, making differentiation difficult (cf ,Fig 9). (b) Contrast-enhanced CT scan shows invaginated mesenteric fat and vessels (arrowhead). Download as PowerPointOpen in Image Viewer

Figure 4b. Transient type small bowel intussusception in a 49-yearold man with abdominal pain who had suffered a fall. (a) Contrastenhanced CT scan demonstrates an amorphous mass (arrow) that is due to bowel wall edema, making differentiation difficult (cf ,Fig 9). (b) Contrast-enhanced CT scan shows invaginated mesenteric fat and vessels (arrowhead). Download as PowerPointOpen in Image Viewer

Figure 5. Longitudinal (top) and serial cross-sectional (bottom) diagrams illustrate a lead point intussusception, with invagination of a segment of the gastrointestinal tract (intussusceptum) into the adjacent segment (intussuscipiens). Thick arrows indicate the lead mass. The intussusceptum appears irregular due to bowel wall edema. The classic three-layer appearance and anatomic detail are often lost. Download as PowerPointOpen in Image Viewer

Figure 6a. Ileoileal intussusception in a 25-year-old man with right lower quadrant pain. (a) Contrast-enhanced CT scan demonstrates an ileoileal intussusception caused by an inverted Meckel diverticulum (arrow). (b, c) CT scan (b) and photograph of the gross surgical specimen (c) show the inverted Meckel diverticulum (arrowheads in b, arrows in c). The typical fat attenuation representing the inverted mesentery is not seen on the CT scan. Download as PowerPointOpen in Image Viewer

Figure 6b. Ileoileal intussusception in a 25-year-old man with right lower quadrant pain. (a) Contrast-enhanced CT scan demonstrates an ileoileal intussusception caused by an inverted Meckel diverticulum (arrow). (b, c) CT scan (b) and photograph of the gross surgical specimen (c) show the inverted Meckel diverticulum (arrowheads in b, arrows in c). The typical fat attenuation representing the inverted mesentery is not seen on the CT scan. Download as PowerPointOpen in Image Viewer

Figure 6c. Ileoileal intussusception in a 25-year-old man with right lower quadrant pain. (a) Contrast-enhanced CT scan demonstrates an ileoileal intussusception caused by an inverted Meckel diverticulum (arrow). (b, c) CT scan (b) and photograph of the gross surgical specimen (c) show the inverted Meckel diverticulum (arrowheads in b, arrows in c). The typical fat attenuation representing the inverted mesentery is not seen on the CT scan. Download as PowerPointOpen in Image Viewer

Figure 7a. Ileoileal intussusception in a 15-year-old girl with recurrent abdominal pain, gastrointestinal bleeding, and anemia. (a, b) Contrast-enhanced CT scans demonstrate an ileoileal intussusception with multiple lead points (arrows). (c) Coronal reformatted CT image demonstrates the entire intussusception (arrowheads) and lead mass (arrow). (d) Photograph of the gross specimen shows multiple venous malformations as lobulated masses (arrows). Scale is in centimeters. Download as PowerPointOpen in Image Viewer

Figure 7b. Ileoileal intussusception in a 15-year-old girl with recurrent abdominal pain, gastrointestinal bleeding, and anemia. (a, b) Contrast-enhanced CT scans demonstrate an ileoileal intussusception with multiple lead points (arrows). (c) Coronal reformatted CT image demonstrates the entire intussusception (arrowheads) and lead mass (arrow). (d) Photograph of the gross specimen shows multiple venous malformations as lobulated masses (arrows). Scale is in centimeters. Download as PowerPointOpen in Image Viewer

Figure 7c. Ileoileal intussusception in a 15-year-old girl with recurrent abdominal pain, gastrointestinal bleeding, and anemia. (a, b) Contrast-enhanced CT scans demonstrate an ileoileal intussusception with multiple lead points (arrows). (c) Coronal reformatted CT image demonstrates the entire intussusception (arrowheads) and lead mass (arrow). (d) Photograph of the gross specimen shows multiple venous malformations as lobulated masses (arrows). Scale is in centimeters. Download as PowerPointOpen in Image Viewer

Figure 7d. Ileoileal intussusception in a 15-year-old girl with recurrent abdominal pain, gastrointestinal bleeding, and anemia. (a, b) Contrast-enhanced CT scans demonstrate an ileoileal intussusception with multiple lead points (arrows). (c) Coronal reformatted CT image demonstrates the entire intussusception (arrowheads) and lead mass (arrow). (d) Photograph of the gross specimen shows multiple venous malformations as lobulated masses (arrows). Scale is in centimeters. Download as PowerPointOpen in Image Viewer

Figure 8a. Ileoileal intussusception and small bowel obstruction caused by an inflammatory fibroid polyp in the distal ileum in a 49year-old woman. (a) Contrast-enhanced CT scan demonstrates invaginated mesenteric fat and vessels (arrow) as well as bowel wall thickening of the intussusceptum and intussuscipiens that obscures the lead mass (arrowhead). (b) Photograph of the gross specimen shows a large (6-cm) pedunculated polypoid mass (arrow). Scale is in centimeters. Download as PowerPointOpen in Image Viewer

Figure 8b. Ileoileal intussusception and small bowel obstruction caused by an inflammatory fibroid polyp in the distal ileum in a 49year-old woman. (a) Contrast-enhanced CT scan demonstrates invaginated mesenteric fat and vessels (arrow) as well as bowel wall thickening of the intussusceptum and intussuscipiens that obscures the lead mass (arrowhead). (b) Photograph of the gross specimen shows a large (6-cm) pedunculated polypoid mass (arrow). Scale is in centimeters. Download as PowerPointOpen in Image Viewer

Figure 9a. Intussusception in a 71-year-old woman with abdominal pain. Contrast-enhanced CT scans of the abdomen demonstrate an intussusception (arrow in a and b) with a round soft-tissue mass serving as a lead point (arrow in c). The mass is isoattenuating relative to bowel wall edema, making differentiation difficult (cf ,Fig 4). The patient was found to have metastatic large B-cell lymphoma of the jejunum. Download as PowerPointOpen in Image Viewer

Figure 9b. Intussusception in a 71-year-old woman with abdominal pain. Contrast-enhanced CT scans of the abdomen demonstrate an intussusception (arrow in a and b) with a round soft-tissue mass serving as a lead point (arrow in c). The mass is isoattenuating relative to bowel wall edema, making differentiation difficult (cf ,Fig 4). The patient was found to have metastatic large B-cell lymphoma of the jejunum. Download as PowerPointOpen in Image Viewer

Figure 9c. Intussusception in a 71-year-old woman with abdominal pain. Contrast-enhanced CT scans of the abdomen demonstrate an intussusception (arrow in a and b) with a round soft-tissue mass serving as a lead point (arrow in c). The mass is isoattenuating relative to bowel wall edema, making differentiation difficult (cf ,Fig 4). The patient was found to have metastatic large B-cell lymphoma of the jejunum. Download as PowerPointOpen in Image Viewer

Figure 10a. Intussusception in a 66-year-old woman with a small bowel obstruction caused by metastatic malignant fibrous histiocytoma. (a, b) Contrast-enhanced CT scans of the abdomen demonstrate a typical intussusception with a lead point (arrow) and associated bowel wall thickening. (c) Contrast-enhanced CT scan shows enhancement of the lead point (arrowheads), a finding that facilitates its identification. (d) Photograph of the gross specimen shows multiple nodules (arrow and arrowheads), the largest of which (arrow) is a pedunculated polypoid mass measuring 5 cm. Scale is in centimeters. Download as PowerPointOpen in Image Viewer

Figure 10b. Intussusception in a 66-year-old woman with a small bowel obstruction caused by metastatic malignant fibrous histiocytoma. (a, b) Contrast-enhanced CT scans of the abdomen demonstrate a typical intussusception with a lead point (arrow) and associated bowel wall thickening. (c) Contrast-enhanced CT scan shows enhancement of the lead point (arrowheads), a finding that facilitates its identification. (d) Photograph of the gross specimen shows multiple nodules (arrow and arrowheads), the largest of which (arrow) is a pedunculated polypoid mass measuring 5 cm. Scale is in centimeters. Download as PowerPointOpen in Image Viewer

Figure 10c. Intussusception in a 66-year-old woman with a small bowel obstruction caused by metastatic malignant fibrous histiocytoma. (a, b) Contrast-enhanced CT scans of the abdomen demonstrate a typical intussusception with a lead point (arrow) and associated bowel wall thickening. (c) Contrast-enhanced CT scan shows enhancement of the lead point (arrowheads), a finding that facilitates its identification. (d) Photograph of the gross specimen shows multiple nodules (arrow and arrowheads), the largest of which (arrow) is a pedunculated polypoid mass measuring 5 cm. Scale is in centimeters. Download as PowerPointOpen in Image Viewer

Figure 10d. Intussusception in a 66-year-old woman with a small bowel obstruction caused by metastatic malignant fibrous histiocytoma. (a, b) Contrast-enhanced CT scans of the abdomen demonstrate a typical intussusception with a lead point (arrow) and associated bowel wall thickening. (c) Contrast-enhanced CT scan shows enhancement of the lead point (arrowheads), a finding that facilitates its identification. (d) Photograph of the gross specimen shows multiple nodules (arrow and arrowheads), the largest of which (arrow) is a pedunculated polypoid mass measuring 5 cm. Scale is in centimeters. Download as PowerPointOpen in Image Viewer

Figure 11a. Ileocolic intussusception in a 41-year-old man with metastatic melanoma who presented with gastrointestinal bleeding. (a, b) Contrast-enhanced CT scans demonstrate an ileocolic intussusception. The tumor that serves as the lead point (arrows in a) originates in the cecum. An intussusception (arrow in b) of the distal ileum is seen extending into the ascending colon. (c) Photograph of the gross specimen shows a large pedunculated polypoid mass (arrow). Scale is in centimeters. Download as PowerPointOpen in Image Viewer

Figure 11b. Ileocolic intussusception in a 41-year-old man with metastatic melanoma who presented with gastrointestinal bleeding. (a, b) Contrast-enhanced CT scans demonstrate an ileocolic intussusception. The tumor that serves as the lead point (arrows in a) originates in the cecum. An intussusception (arrow in b) of the distal ileum is seen extending into the ascending colon. (c) Photograph of the gross specimen shows a large pedunculated polypoid mass (arrow). Scale is in centimeters. Download as PowerPointOpen in Image Viewer

Figure 11c. Ileocolic intussusception in a 41-year-old man with metastatic melanoma who presented with gastrointestinal bleeding. (a, b) Contrast-enhanced CT scans demonstrate an ileocolic intussusception. The tumor that serves as the lead point (arrows in a) originates in the cecum. An intussusception (arrow in b) of the distal ileum is seen extending into the ascending colon. (c) Photograph of the gross specimen shows a large pedunculated polypoid mass (arrow). Scale is in centimeters. Download as PowerPointOpen in Image Viewer

Figure 12. Colocolic intussusception secondary to lipoma in a 73year-old woman. Contrast-enhanced CT scan of the abdomen demonstrates an intraluminal mass with fat attenuation (arrow). Download as PowerPointOpen in Image Viewer

Figure 13a. Colocolic intussusception secondary to adenocarcinoma in an 83-year-old woman. Contrast-enhanced CT scans of the abdomen demonstrate the classic findings of a lead point intussusception (arrowheads) with invaginated mesenteric fat and vessels (arrows). Download as PowerPointOpen in Image Viewer

Figure 13b. Colocolic intussusception secondary to adenocarcinoma in an 83-year-old woman. Contrast-enhanced CT scans of the abdomen demonstrate the classic findings of a lead point intussusception (arrowheads) with invaginated mesenteric fat and vessels (arrows).