(Radiographics. 1999;19:1102-1104.)
© RSNA, 1999
Gastrointestinal Case of the Day1
Valerie Drnovsek, MD, PhD,
Michael B. Ruff, MD,
Paul A. Riehl, MD and
Branko M. Plavsic, MD, PhD
1 From the Departments of Radiology (V.D.) and Pathology (P.A.R.), Touro Infirmary, New Orleans, La, and the Department of Radiology, Tulane University, 1430 Tulane Ave, New Orleans, LA 70112 (M.B.R., B.M.P.). From the 1998 RSNA scientific assembly. Received September 24, 1998; revision requested November 9 and received November 16; accepted November 24. Address reprint requests to B.M.P.
Index Terms: Colon, neoplasms, 75.31 • Colon, stenosis or obstruction, 75.732 • Intestinal neoplasms, diagnosis, 75.31 • Intussusception, 75.732
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HISTORY
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A 65-year-old man with a history of rectal bleeding presented with colicky pain of 12 hours duration and a palpable mass in the right and middle upper abdomen. Computed tomography (CT) of the abdomen was performed.
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FINDINGS
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At abdominal CT, an oblong mass composed of alternating low- and high-attenuation layers was visualized in the right upper quadrant (Fig 1). A classic "target sign" was seen in the ascending colon. Intraluminal areas of fat attenuation and contrast material–enhanced vessels were seen within both the ascending and transverse colon (Fig 2). In addition, an ill-defined, solid enhancing mass 5 cm in diameter was seen distally in the colon (Fig 3).
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Figures 1-3. (1) Abdominal CT scan obtained after oral and intravenous administration of contrast material demonstrates a collection of alternating low- and high-attenuation layers surrounded by a thin rim of enhancement (arrowheads). (2) CT scan obtained caudad to Figure 1 shows a target sign in the region of the ascending colon (open arrow). Intraluminal areas of fat attenuation (solid arrows) and contrast-enhanced vessels (arrowheads) are seen in the ascending and transverse colon. (3) CT scan shows an enhancing mass within the transverse colon (arrowheads).
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Figures 1-3. (1) Abdominal CT scan obtained after oral and intravenous administration of contrast material demonstrates a collection of alternating low- and high-attenuation layers surrounded by a thin rim of enhancement (arrowheads). (2) CT scan obtained caudad to Figure 1 shows a target sign in the region of the ascending colon (open arrow). Intraluminal areas of fat attenuation (solid arrows) and contrast-enhanced vessels (arrowheads) are seen in the ascending and transverse colon. (3) CT scan shows an enhancing mass within the transverse colon (arrowheads).
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Figures 1-3. (1) Abdominal CT scan obtained after oral and intravenous administration of contrast material demonstrates a collection of alternating low- and high-attenuation layers surrounded by a thin rim of enhancement (arrowheads). (2) CT scan obtained caudad to Figure 1 shows a target sign in the region of the ascending colon (open arrow). Intraluminal areas of fat attenuation (solid arrows) and contrast-enhanced vessels (arrowheads) are seen in the ascending and transverse colon. (3) CT scan shows an enhancing mass within the transverse colon (arrowheads).
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DIAGNOSIS: Chronic ileocolocolic intussusception secondary to a mobile cecum and a benign fibrovascular mass.
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DISCUSSION
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Intussusception (invagination) is a prolapse of a portion of the bowel into the lumen of an immediately adjacent segment of the bowel. The intussuscipiens is the part of the intestine into which the adjoining portion has prolapsed, and the intussusceptum is the prolapsed segment. In adults, intussusceptions account for less than 16% of all obstructions, and the cause can be identified in approximately 90% of cases. About 60% of adult intussusceptions are related to neoplasms (1). The large bowel is affected in 45% of cases and the small bowel in 55%. Adult colonic intussusceptions are caused by malignant neoplasms in 48% of cases and benign neoplasms in 21%; the remaining cases are nonneoplastic. In contrast, small bowel intussusceptions result from benign neoplasms in 40% of cases, from malignant neoplasms in 17%, and from nonneoplastic lesions in the remaining cases. About one-third of adult intussusceptions may result from postsurgical changes (eg, dense adhesions adjacent to the sutures, submucosal bowel edema, discoordinate motility) (2). Other causes include invaginated Meckel diverticulum (3), celiac disease (4), and gastrointestinal disease associated with acquired immunodeficiency syndrome (5). When an intussusception is diagnosed in an adult, a tumor work-up is essential. Intussusceptions are the leading cause of bowel obstruction in children and are idiopathic in more than 80% of cases.
Symptoms of adult intussusception include cramping abdominal pain, nausea and vomiting, abdominal tenderness and distention, and change in bowel habits (1). A palpable mass may be seen in up to one-half of patients and bloody stool in a majority of patients. Intussusception may be either acute or subacute at presentation.
CT findings in intussusception secondary to neoplasm include thickening of the affected bowel segment, areas of fat attenuation within the abnormal bowel loop, concentric rings (target sign), and an intraluminal soft-tissue mass at the leading end of the intussusceptum (6,7). In our patient, the bowel wall was not significantly thickened but other signs were present. Mesenteric and mesocolic fat and contrast-enhanced mesenteric blood vessels were seen within the lumen of the intussuscipiens.
The patient underwent surgical resection that included portions of the terminal ileum, cecum, appendix, and ascending colon. The gross specimen demonstrated two distinct lesions just distal to the ileocecal valve and separated by only a few centimeters (Fig 4). The larger mass served as the lead point of the intussusceptum. The mass was 50 mm in diameter and proved to be composed of fibrous and vascular elements with edema at histologic analysis (Fig 5). It was a head of intussusceptum that over time developed chronic changes of fibrosis and vascular ectasia due to recurring episodes of intussusception caused by the mobility of the cecum and of a portion of the ascending colon. The mass did not fulfill the pathologic criteria for a fibrovascular polyp. The smaller mass, a tubulovillous adenoma in which an invasive adenocarcinoma had arisen, measured 2.5 x 1.2 mm. The mobile cecum was able to follow the intussusceptum as far as the descending colon, where it was found at surgery. The patient's postoperative course was uneventful, and he was discharged 10 days after surgery.
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Figure 4. Surgical specimen of the terminal ileum, cecum, and proximal ascending colon demonstrates a large mass (arrowheads) that served as a lead point of intussusception. In addition, carcinoma is seen arising in a tubulovillous adenoma (arrow).
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Figure 5. Low-power photomicrograph (original magnification, x10; hematoxylin-eosin stain) of the lead mass shows superficial ulceration, transmural edema, vascular ectasia (arrowheads), and fibrosis.
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References
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Agha FP. Intussusception in adults. AJR 1986; 146:527-531.[Abstract/Free Full Text]
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Williamson RC, Cooper MJ, Thomas WE. Intussusception of invaginated Meckel's diverticulum. J R Soc Med 1984; 77:652-655.[Abstract]
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Cohen MD, Lintott DJ. Transient small bowel intussusception in adult celiac disease. Clin Radiol 1978; 29:529-534.[Medline]
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Wood BJ, Kumar PN, Cooper C, Silverman PM, Zeman RK. AIDS-associated intussusception in young adults. J Clin Gastroenterol 1995; 21:158-162.[Medline]
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Lorigan JG, Dubrow RA. The computed tomographic appearances and clinical significance of intussusception in adults with malignant neoplasms. Br J Radiol 1990; 63:257-262.[Abstract/Free Full Text]
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Gayer G, Apter S, Hofmann C, et al. Intussusception in adults: CT diagnosis. Clin Radiol 1998; 53:53-57.[Medline]
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HISTORY
FINDINGS
