DOI: 10.1148/rg.234025123
(Radiographics. 2003;23:847-851.)
© RSNA, 2003
Best Cases from the AFIP
Omental Lymphangioma with Small-Bowel Volvulus1
Colin R. Mar, MD,
Chitra Pushpanathan, MD,
David Price, MD and
Benvon Cramer, MD
1 From the Departments of Diagnostic Imaging (C.R.M., B.C.), Pathology (C.P.), and Surgery (D.P.), Janeway Children’s Health and Rehabilitation Centre, St John’s, Newfoundland, Canada. Received July 11, 2002; revision requested August 20 and received September 19; accepted September 23. Address correspondence to C.R.M., Department of Diagnostic Radiology, Memorial University of Newfoundland, Health Sciences Centre, 300 Prince Philip Dr, St John’s, Newfoundland, Canada A1B 3V6 (e-mail: cmar72@hotmail.com).
Index Terms: Intestines, volvulus, 74.7233 • Lymphangioma, 799.3194 • Omentum, neoplasms, 799.3194
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History
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A 4-year-old boy presented with abdominal pain and a history of nonbilious vomiting of increasing frequency over the previous 2 days. He had been healthy until then with an unremarkable medical and surgical history.
The patient was in stable condition at examination, but a lower abdominal mass was palpated. There was no hepatomegaly, splenomegaly, or clinical lymphadenopathy. The laboratory values were as follows: leukocyte count, 21.7 x 109/L (normal range, 5.0–12.0 x 109/L); hemoglobin, 118 g/L (normal range, 110–140 g/L); 
-fetoprotein, <2 µg/L (normal range, 0–8.5 µg/L); and ß–human chorionic gonadotropin, <5 U/L (normal range, 0–10 U/L).
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Imaging Findings
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An abdominal radiographic series demonstrated multiple distended loops of small intestine with air-fluid levels (Fig 1), an appearance consistent with an obstruction. There was no soft-tissue mass or calcifications.
Ultrasonography (US) demonstrated a bilobed, cystic, intraperitoneal pelvic mass that measured 11.2 cm in its long axis and contained low-level internal echoes but no calcifications (Fig 2). It was located left of midline and extended inferiorly to the bladder. Other cystic structures were noted adjacent to the primary lesion, but no communication was demonstrated. There were also multiple dilated loops of small intestine and free intraperitoneal fluid in close proximity. The superior mesenteric artery and superior mesenteric vein were in the normal anatomic orientation.
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Figure 2a. (a) US image shows a bilobed cystic mass with low-grade internal echoes. (b) US image obtained superior to a shows a segment of dilated small intestine in addition to free intraperitoneal fluid.
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Figure 2b. (a) US image shows a bilobed cystic mass with low-grade internal echoes. (b) US image obtained superior to a shows a segment of dilated small intestine in addition to free intraperitoneal fluid.
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Computed tomography (CT) also showed the bilobed cystic mass in the left hemiabdomen (Fig 3). The mass extended from the level of the left kidney to just above the bladder, and adjacent cystic structures were again noted. Centrally, there were markedly distended small-bowel loops, which were suggestive of obstruction. Next to these was a mass of mesenteric folds and small-bowel loops that spiraled about the superior mesenteric artery and superior mesenteric vein. This finding was in keeping with volvulus, but these vessels again had a normal orientation and there was no other evidence of bowel malrotation.
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Figure 3a. CT images obtained with intravenously administered contrast material (a obtained at a higher level than b) show the mesentery swirling around the superior mesenteric artery and superior mesenteric vein as a result of small-bowel volvulus. Multiple loops of dilated small intestine are seen, one of which is closely associated with the superior aspect of the bilobed cystic mass in the left hemiabdomen.
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Figure 3b. CT images obtained with intravenously administered contrast material (a obtained at a higher level than b) show the mesentery swirling around the superior mesenteric artery and superior mesenteric vein as a result of small-bowel volvulus. Multiple loops of dilated small intestine are seen, one of which is closely associated with the superior aspect of the bilobed cystic mass in the left hemiabdomen.
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Pathologic Evaluation
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At laparotomy, the peritoneum contained a large omental cyst with at least 720° of small intestine twisted around it. This correlated with the bowel loops and mesentery that swirled about the mesenteric vessels at CT. There was marked lymphatic obstruction proximally and early venous obstruction in the dilated segments. The volvulus was reduced, and the cyst and adjacent intestine were resected together.
The gross specimen was a 360-g cyst of 13 x 10 x 8 cm (Fig 4). It consisted of three large and multiple smaller loculi. Their walls varied from thin and transparent to a fatty admixture. Although a definite plane between the intestine and the cyst could not be demonstrated, there was no communication. The attached segment of intestine was dilated to 4 cm with effaced mucosa.
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Figure 4a. (a) Photograph of the gross specimen shows that the cyst is multiloculated with a short segment of small intestine plastered to its surface. There is no communication between the intestine and the cyst. (b) Photograph of the bisected mass shows a good correlation with the US and CT appearances. The walls of the two large loculi are thin and semitransparent.
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Figure 4b. (a) Photograph of the gross specimen shows that the cyst is multiloculated with a short segment of small intestine plastered to its surface. There is no communication between the intestine and the cyst. (b) Photograph of the bisected mass shows a good correlation with the US and CT appearances. The walls of the two large loculi are thin and semitransparent.
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Histologic examination of the cyst portions revealed a well-differentiated fibromuscular wall with focal areas of lymphatic endothelial lining (Fig 5). Distended lymphatics were noted in the adjacent fibrofatty stroma. The small-bowel mucosa was intact with lymphatic distention in the villi. A diagnosis of an omental lymphangioma with small-bowel volvulus was thus confirmed.
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Figure 5. Photomicrograph (original magnification, x2; hematoxylin-eosin stain) of a representative section of one of the large loculi shows an attenuated lining and a fibromuscular wall with scattered lymphocytes. The adjacent fibrofatty stroma contains dilated lymphatics.
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Discussion
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Mesenteric cysts, which include lymphangiomas, are an uncommon lesion, particularly in children (1,2). Partial or complete small-bowel obstruction is a known complication and may occur by extrinsic luminal compression, by traction on the mesentery (1,3), or, as in this case, by volvulus (2,4). The most common cause of pediatric midgut volvulus is bowel malrotation (2). Small intestine swirling about the superior mesenteric vessels has been previously described in such cases (5). Chronic midgut volvulus with a mesenteric lymphangioma and underlying malrotation has also been reported (6).
Ros et al (7) have presented the US and CT features of 41 cases of mesenteric and omental cysts, including pathologic correlation. Their histologic classification included (a) lymphangioma, (b) enteric duplication cyst, (c) enteric cyst, (d) mesothelial cyst, and (e) nonpancreatic pseudocyst. Nineteen cases in the series were of the first type, as is the case presented herein. In these 19 cases, 11 patients were female and eight were male, with an age range of 2 months to 18 years. This younger predominance favors a congenital origin over an acquired one, and obstructed lymphatics have been proposed (8).
Ninety-five percent of lymphangiomas are found in the neck and axilla (9). The remainder are found in the mediastinum, omentum, mesentery, retroperitoneum, and bone (7). Malignant degeneration is usually to a low-grade sarcoma, but this rarely occurs (10).
In the series of Ros et al (7), abdominal distention with a palpable mass was the most common presentation (7). However, the lesion may not be palpable due to its flaccid and mobile nature (11). Symptoms were present in all patients and included pain, vomiting, and diarrhea (7). A recent series of seven abdominal lymphangiomas documented ascites and fever, each of which occurred in three cases (12).
Plain radiography may demonstrate a small-bowel obstruction and possibly a noncalcified soft-tissue mass or displaced bowel loops (7). The typical US appearance is a well-circumscribed anechoic mass with posterior acoustic enhancement (13,14). However, internal septa and solid echogenicity with a honeycomb pattern have also been described (11). In the series of Ros et al (7), 13 patients underwent US, which was the favored modality for providing internal detail. Seven had multiple thin septa. They also showed variable internal echogenicity, which is accounted for by the various contents that are possible (7).
The CT findings were similar. Of the 10 studies performed, seven demonstrated multiloculated fluid-filled masses and two demonstrated bilobed fluid-filled masses. The attenuation of the fluid ranged from that of fluid to that of fat, again according to the different contents (7). Lymphangiomas have also been characterized as being well defined with a thin wall and occasionally with septa. The lesion may be distinguished from ascites by the absence of bowel loop separation or fluid in the typical sites, such as the cul-de-sac, or the presence of focal septa (15).
The magnetic resonance (MR) imaging findings in a series of 17 cases have been presented. Only one of these was mesenteric, but the features were summarized as follows: 13 lesions were isointense or slightly hypointense to muscle on T1-weighted images, and 16 were hyperintense to fat on T2-weighted images. The authors found MR imaging useful in providing increased contrast with the adjacent muscle and vasculature (8).
The differential diagnosis includes the other histologic types of mesenteric and omental cysts mentioned earlier, and there are no specific radiologic features. Another consideration is a cystic leiomyoma or leiomyosarcoma, and again differentiation requires histologic evaluation (7). A cystic teratoma should also be included, but one would expect fat content with one or more clusters of calcifications (16). Nevertheless, a mesenteric lymphangioma with peripherally calcified caseous material has been documented (17). Mesotheliomas may also appear cystic, thus requiring a histologic diagnosis, but these usually occur in middle-aged women (18).
In our patient, a small-bowel loop was closely applied to the lymphangioma and had to be excised with the lesion. This was seen in 14 of the 19 cases in the series of Ros et al (7), indicating the possibility of a more aggressive nature of this diagnosis relative to the other mesenteric cysts. The recurrence rate has been shown to be lowest with complete resection versus aspiration and injection of a sclerosing agent (19). Our patient’s surgery was well-tolerated, and he was discharged without complications or further incidents.
Mesenteric and omental cysts must be considered when evaluating children with abdominal pain and masses, and these cysts are readily imaged with US. Associated clinical findings of small-bowel obstruction should prompt suspicion of midgut volvulus, which has a distinct and impressive appearance at CT.
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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 or more of these cases are 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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- Christensen JA, Fuller JW, Hallock JA, Sherman RT. Mesenteric cysts: a cause of small bowel obstruction in children. Am Surg 1975; 41:352-354.[Medline]
- Namasivayam J, Ziervogel MA, Hollman AS. Case report: volvulus of a mesenteric cyst—an unusual complication diagnosed by CT. Clin Radiol 1992; 46:211-212.[CrossRef][Medline]
- Kovalivker M, Mitovic A. Obstruction and gangrene of bowel with perforation due to a mesenteric cyst in a newborn. J Pediatr Surg 1987; 22:277-356.
- Traubici J, Daneman A, Wales P, Gibbs D, Fecteau A, Kim P. Mesenteric lymphatic malformation associated with small-bowel volvulus: two cases and a review of the literature. Pediatr Radiol 2002; 32:362-365.[CrossRef][Medline]
- Fisher JK. Computed tomographic diagnosis of volvulus in intestinal malrotation. Radiology 1981; 140:145-146.[Abstract/Free Full Text]
- Yoon HK, Kim BK. Chronic midgut volvulus with mesenteric lymphatic malformations: a case report. Pediatr Radiol 1998; 28:611.[CrossRef][Medline]
- Ros PR, Olmsted WW, Moser RP, Jr, Dachman AH, Hjermstad BH, Sobin LH. Mesenteric and omental cysts: histologic classification with imaging correlation. Radiology 1987; 164:327-332.[Abstract/Free Full Text]
- Siegel M, Glazer HS, St Amour TE, Rosenthal DD. Lymphangiomas in children: MR imaging. Radiology 1989; 170:467-470.[Abstract/Free Full Text]
- Singh S, Baboo ML, Pathak IC. Cystic lymphangioma in children: report of 32 cases including lesions at rare sites. Surgery 1971; 169:947-951.
- Hardin WJ, Hardy JD. Mesenteric cysts. Am J Surg 1970; 119:640-645.[CrossRef][Medline]
- Geer LL, Mittelstaedt CA, Staab EV, Gaisie G. Mesenteric cyst: sonographic appearance with CT correlation. Pediatr Radiol 1984; 14:102-104.[CrossRef][Medline]
- Konen O, Rathaus V, Dlugy E, et al. Childhood abdominal cystic lymphangioma. Pediatr Radiol 2002; 32:88-94.[CrossRef][Medline]
- Mittelstaedt CA. Ultrasonic diagnosis of omental cysts. Radiology 1975; 117(3 pt 1):673-676.[Abstract]
- Haller JO, Schneider M, Kassner EG, et al. Sonographic evaluation of mesenteric and omental masses in children. AJR Am J Roentgenol 1978; 130:269-274.[Abstract]
- Lugo-Olivieri CH, Taylor GA. CT differentiation of large abdominal lymphangioma from ascites. Pediatr Radiol 1993; 23:129-130.[CrossRef][Medline]
- Bowen B, Ros PR, McCarthy MJ, Olmsted WW, Hjermstad BM. Gastrointestinal teratomas: CT and US appearance with pathologic correlation. Radiology 1987; 162:431-433.[Abstract/Free Full Text]
- Hatten MT, Hamrick-Turner JE, Smith DB. Mesenteric cystic lymphatic malformation: radiologic appearance mimicking cystic teratoma. Pediatr Radiol 1996; 26:458-460.[CrossRef][Medline]
- Katsube Y, Mukai K, Silverberg SG. Cystic mesothelioma of the peritoneum: a report of five cases and review of the literature. Cancer 1982; 50:1615-1622.[CrossRef][Medline]
- Alqahtani A, Nguyen LT, Flageole H, Shaw K, Laberge JM. 25 years’ experience with lymphangiomas in children. J Pediatr Surg 1999; 34:1164-1168.[CrossRef][Medline]
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