(Radiographics. 2002;22:1217-1222.)
© RSNA, 2002
Best Cases from the AFIP
Ileocecal Enteric Duplication Cyst: Radiologic-Pathologic Correlation1
Samuel C. Tong, MD,
Martha Pitman, MD and
Sudha A. Anupindi, MD
1 From the Departments of Radiology (S.C.T., S.A.A.) and Pathology (M.P.), Massachusetts General Hospital, 34 Fruit St, White 246, Boston, MA 02114. Received March 1, 2002; revision requested March 27 and received May 6; accepted May 6. Address correspondence to S.A.A. (e-mail: sanupindi@partners.org).
Index Terms: Intestines, abnormalities, 742.141, 752.141 • Intestines, cysts, 742.141, 752.141
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History
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A 13-year-old boy with no medical or surgical history presented to the emergency room with acute abdominal pain followed by multiple episodes of vomiting. He had recently eaten some uncooked cookie dough but nothing else for the day. His vital signs were normal, and he was afebrile. The patient’s abdomen was soft, flat, and nontender with good bowel sounds and no masses. The white blood cell count was 12,800/µL (normal range, 4.5–13.5 x 103/µL). Appendicitis was suspected.
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Imaging Findings
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Initially, pelvic computed tomography (CT) with only rectal contrast material was performed. There was a large, well-circumscribed, low-attenuation, lobulated mass within the cecum (Fig 1). The distal small intestine was mildly dilated and filled with fluid. A normal appendix was identified, and the diagnosis of appendicitis was excluded.
Abdominal CT with intravenous and oral contrast material followed. It demonstrated a lobulated, tubular mass that measured approximately 9 cm in the anterior-posterior dimension and approximately 3 cm in the transverse dimension. The mass extended into the cecum and ascending colon (Fig 2a). The mass demonstrated peripheral enhancement and uniform central low attenuation of 30 HU. The mass was now dumbbell-shaped (Fig 2a), in contrast to the lobulated appearance in the prior pelvic CT study. The distal ileum was mildly dilated.
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Figure 2a. (2a) CT scan shows a homogeneous, dumbbell-shaped mass with thin, uniform rim enhancement (arrows) that extends into the cecum near the region of the ileocecal valve. (2b) CT scan shows the changing shape of the lesion (arrows). The attenuation value in the central part of the lesion (30 HU) indicates that it is a cyst.
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Figure 2b. (2a) CT scan shows a homogeneous, dumbbell-shaped mass with thin, uniform rim enhancement (arrows) that extends into the cecum near the region of the ileocecal valve. (2b) CT scan shows the changing shape of the lesion (arrows). The attenuation value in the central part of the lesion (30 HU) indicates that it is a cyst.
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The abdominal CT study was immediately followed by a single-contrast barium enema study. It showed a large mass within the cecum. The mucosal surface was normal, suggesting a submucosal origin (Fig 3a). This mass corresponded to the lesion seen in the abdominal and pelvic CT studies. There was reflux of contrast material into a normal terminal ileum. The mass was malleable and mobile and changed shape with compression (Fig 3b, 3c).
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Figure 3a. (a) Image from a barium enema study shows a filling defect in the cecum (arrow), which represents the submucosal mass. Contrast material fills the entire colon to the level of the cecum, and there is reflux of contrast material into the terminal ileum (arrowhead) without evidence of intussusception. (b) Spot image from the barium enema study obtained with manual compression shows flow of contrast material around the mass (arrow). The mass was soft and malleable, changing shape and position. (c) Radiograph from the barium enema study shows the location of the lesion in the cecum (arrow). There is no obstruction.
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Figure 3b. (a) Image from a barium enema study shows a filling defect in the cecum (arrow), which represents the submucosal mass. Contrast material fills the entire colon to the level of the cecum, and there is reflux of contrast material into the terminal ileum (arrowhead) without evidence of intussusception. (b) Spot image from the barium enema study obtained with manual compression shows flow of contrast material around the mass (arrow). The mass was soft and malleable, changing shape and position. (c) Radiograph from the barium enema study shows the location of the lesion in the cecum (arrow). There is no obstruction.
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Figure 3c. (a) Image from a barium enema study shows a filling defect in the cecum (arrow), which represents the submucosal mass. Contrast material fills the entire colon to the level of the cecum, and there is reflux of contrast material into the terminal ileum (arrowhead) without evidence of intussusception. (b) Spot image from the barium enema study obtained with manual compression shows flow of contrast material around the mass (arrow). The mass was soft and malleable, changing shape and position. (c) Radiograph from the barium enema study shows the location of the lesion in the cecum (arrow). There is no obstruction.
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A normal appendix excluded the diagnosis of appendicitis, and reflux of contrast material into a normal terminal ileum excluded the diagnosis of ileocolic intussusception or obstruction. The peripheral rim enhancement, lack of central enhancement, and malleability of the lesion were consistent with a cystic rather than a solid lesion. The central attenuation value of 30 HU indicated complex, possibly proteinaceous fluid contained within the cystic lesion. These findings together strongly suggested the diagnosis of a cecal duplication cyst, which was probably causing intermittent obstruction and mimicked an intussusception.
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Pathologic Evaluation
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Shortly after these studies, the patient was taken to the operating room and underwent a laparotomy. The cecum, terminal ileum, and appendix were resected, and an end-to-end anastomosis was performed.
Gross pathologic examination of the resected specimen demonstrated a 6.0 x 3.0 x 3.0-cm, round, submucosal mass (Fig 4) that extended from the ileum into the cecum. It was covered by normal colonic mucosa (Fig 5). The mass was cystic with a tan to white, smooth-lined wall and yellow, thick, viscous contents (Fig 6). The appendix was normal. Histologic evaluation demonstrated a cyst lining composed of normal colonic mucosa (Fig 7). The gross and histologic findings confirmed the diagnosis of an enteric duplication cyst arising from the ileum with extension into the cecum.
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Figure 4. Photograph of the gross specimen shows the resected distal ileum and dilated cecum surrounding the large, rounded mass (black arrows). The normal appendix is seen protruding from the mass (white arrow).
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Figure 5. Photograph of the opened specimen shows flattened but otherwise normal mucosa splayed across the surface, thus confirming the submucosal origin of the mass. The ileocecal valve is seen (arrow).
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Discussion
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Enteric duplication cysts are an uncommon congenital abnormality. They can occur anywhere along the digestive tract on the mesenteric side. The small intestine is most commonly involved, with the order from most to least common being the ileum, jejunum, and duodenum. Most duplication cysts manifest during the first year of life, although some occasionally manifest in older patients (1). Children can present with a variety of symptoms including abdominal distention, vomiting, bleeding, a palpable abdominal mass, and rarely urinary frequency and hesitancy. Complications include perforation, intussusception, bowel obstruction from adjacent pressure or mass effect, volvulus, and associated malignancy (2). Malignant lesions arising from duplication cysts are rare, particularly in children. Inoue and Nakamura (3) reviewed 18 cases of malignancies arising in duplication cysts and reported that the frequency of associated malignancies is highest in the colon (67%). All the cases occurred in adults with an age range of 33–65 years. Fourteen of the cases were adenocarcinomas, and four cases were squamous cell carcinomas. In one reported case, a carcinoid tumor developed in a rectal duplication cyst in a 16-year-old girl, but this is rare (4). Duplication cysts can be associated with other congenital abnormalities, such as vertebral or urogenital malformations (5). However, no other congenital abnormality was present in the case reported herein.
The most common imaging modalities used to image duplication cysts are ultrasonography (US) and barium studies. CT and magnetic resonance imaging are less often used but can be helpful in difficult cases that require a multiplanar approach. At US, duplication cysts demonstrate an echogenic inner mucosal layer and a hypoechoic outer muscular layer (Fig 8). This appearance is usually not circumferential, as the layers are often nonuniform in thickness, but this double-layered wall is often found in over 50% of cases (6). A barium study such as an upper gastrointestinal series with small bowel follow-through or a barium enema examination may demonstrate a submucosal mass with mass effect extending into the lumen of the gastrointestinal tract. The duplication cyst can also sometimes act as the lead point for an intussusception. A partially obstructing duplication cyst may simulate an intussusception on barium enema examination as well (7).
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Figure 8. US scan of an enteric duplication cyst in another patient shows the characteristic echogenic inner mucosal layer (white arrow) and hypoechoic outer muscular layer (black arrow). (Courtesy of Sjirk Westra, MD, Massachusetts General Hospital, Boston, Mass.)
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Some enteric duplication cysts contain gastric mucosa and may be demonstrated with a technetium-99m sodium pertechnetate study. The Tc-99m pertechnetate radionuclide scan shows tracer uptake within the ectopic gastric mucosa of the mass, similar to the uptake seen in gastric mucosa within a Meckel’s diverticulum. The frequency of gastric mucosa within duplication cysts is quite variable among studies and is reported to be 17%–36% (8–10). Gastrointestinal bleeding occurs primarily because of ulceration of the gastric mucosa, intussusception, or pressure necrosis (9). Perforation can also occur, leading to severe gastrointestinal bleeding. The sensitivity of Tc-99m pertechnetate imaging is reported to be 75% (11,12). The occurrence of gastric mucosa in duplication cysts is not insignificant and should be considered in the differential diagnosis of gastrointestinal bleeding in a child.
At CT, a duplication cyst will appear as a nonenhancing cystic mass. One advantage of CT is the ability to use Hounsfield unit measurement to determine the contents of a cystic lesion. The central attenuation value can demonstrate the presence of simple fluid, but the fluid may be of higher attenuation if there is hemorrhage or proteinaceous material (13).
Although CT is not the usual method for diagnosing a duplication cyst, CT was used first in the case reported herein because of the clinical suspicion of appendicitis. The findings at CT and barium enema examination provided the clues to the correct diagnosis of an ileocecal duplication cyst. The cystic nature of the structure allowed malleability of the mass at barium enema examination and explained the difference in shape in the two CT studies. The mass appeared lobulated in the CT study performed with rectal contrast material but appeared tubular in the CT study performed with intravenous and oral contrast material. The increased attenuation of the lesion on the CT scans can also be explained by the high protein content of the viscous fluid within the cyst. The differential diagnosis included appendicitis and intussusception. Appendicitis was excluded by identification of a normal appendix at CT, and intussusception was excluded by reflux of contrast material into the terminal ileum on barium enema examination.
The treatment of choice for enteric duplication cysts is surgical excision (2). In the case reported herein, the patient had an uneventful course after resection of the duplication cyst.
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Footnotes
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Editor’s Note.—Everyone who has taken the course in radiologic pathology at the Armed Forces Institute of Pathology (AFIP) remembers bringing two beautifully illustrated cases for accession to the Institute. In recent years, the staff of the Department of Radiologic Pathology has judged the "best cases" by organ system, and recognition is given to the winners on the last day of the class. With each issue of RadioGraphics, one of these cases is published, written by the winning resident. Radiologic-pathologic correlation is emphasized, and the causes of the imaging signs of various diseases are illustrated.
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References
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- Choi SO, Park WH, Kim SP. Enteric duplications in children: an analysis of 6 cases. J Korean Med Sci 1993; 8:482-487.[Medline]
- Otter MI, Marks CG, Cook MG. An unusual presentation of intestinal duplication with a literature review. Dig Dis Sci 1996; 41:627-629.[CrossRef][Medline]
- Inoue Y, Nakamura H. Adenocarcinoma arising in colonic duplication cysts with calcification: CT findings of two cases. Abdom Imaging 1998; 23:135-137.[CrossRef][Medline]
- Rubin SZ, Mancer JF, Stephens CA. Carcinoid in a rectal duplication: a unique pediatric surgical problem. Can J Surg 1981; 24:351-352.[Medline]
- Dutheil-Doco A, Ducou Le Pointe H, Larroquet M, Ben Lagha N, Montagne J. A case of perforated cystic duplication of the transverse colon. Pediatr Radiol 1998; 28:20-22.[CrossRef][Medline]
- Barr LL, Hayden CK, Jr, Stansberry SD, Swischuk LE. Enteric duplication cysts in children: are their ultrasonographic wall characteristics diagnostic? Pediatr Radiol 1990; 20:326-328.[CrossRef][Medline]
- Sonoda N, Matsuzaki S, Ono A, et al. Duplication of the caecum in a neonate simulating intussusception. Pediatr Radiol 1985; 15:427-428.[CrossRef][Medline]
- Lecouffe P, Spyckerelle C, Venel H, Meuriot S, Marchandise X. Use of pertechnetate 99mTc for abdominal scanning in localising an ileal duplication cyst: case report and review of the literature. Eur J Nucl Med 1992; 19:65-67.[Medline]
- Royal SA, Hedlund GL, Kelly DR. Ileal duplication cyst. AJR Am J Roentgenol 1994; 163:98.[Free Full Text]
- Royle SG, Doig CM. Perforation of the jejunum secondary to a duplication cyst lined with ectopic gastric mucosa. J Pediatr Surg 1988; 23:1025-1026.[CrossRef][Medline]
- Rose JS, Gribetz D, Krasna IH. Ileal duplication cyst: the importance of sodium pertechnetate Tc 99m scanning. Pediatr Radiol 1978; 6:244-246.[CrossRef][Medline]
- Wardell S, Vidican DE. Ileal duplication cyst causing massive bleeding in a child. J Clin Gastroenterol 1990; 12:681-684.[Medline]
- Kelly RB, Mahoney PD, Johnson JF. CT demonstration of an unusual enteric duplication cyst. J Comput Assist Tomogr 1986; 10:506-507.[Medline]
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