DOI: 10.1148/radiol.2422040431
(Radiology 2007;242:628-631.)
© RSNA, 2007
Case 107: Lymphoma of the Mesentery1
Panuch Yenarkarn, MBBS2,
Ruedi F. Thoeni, MD and
Douglas Hanks, MD
1 From the Department of Radiology, University of California San Francisco Medical School, 505 Parnassus Ave, Box 0628, San Francisco, CA 94143-0628 (P.Y., R.F.T.); and Department of Pathology, University of California San Francisco Medical School, San Francisco General Hospital, San Francisco, Calif (D.H.). Received March 1, 2004; revision requested May 12; revision received June 16; accepted July 21; final version accepted August 16.
Correspondence: Address correspondence to R.F.T. (e-mail: Ruedi.Thoeni{at}radiology.ucsf.edu).
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HISTORY
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A 59-year-old man with a history of hepatitis C infection underwent abdominal computed tomography (CT) for surveillance of possible progression of hepatitis C and to rule out hepatocellular carcinoma. He had no clinical history of fever, abdominal pain, or palpable masses. There was no history of prior surgery or radiation therapy, and he was seronegative for human immunodeficiency virus. Physical examination findings were normal, and all laboratory tests were negative. Abdominal CT was performed with 800 mL of 2% diatrizoate meglumine and sodium (Gastrografin; Bracco Diagnostics, Princeton, NJ) administered orally and 140 mL of iohexol (300 mg of iodine per milliliter) (Omnipaque; Nycomed, New York, NY) administered intravenously. A triple-phase liver protocol was used. Images were obtained in the portal venous and late arterial phases. The delayed phase images are not shown.
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IMAGING FINDINGS
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Abdominal CT consisted of a triple-phase liver protocol performed with intravenous contrast material enhancement in the late arterial, portal venous, and delayed phases (40, 80, and 180 seconds delay, respectively). Images were obtained in the portal venous phase (Figure) and demonstrated increased attenuation and fat stranding in the root of the small-bowel mesentery. Multiple nodules of soft-tissue attenuation were seen surrounding the mesenteric vessels (Figure, parts b–d). The fat around the mesenteric vessels was preserved. Multiple subcentimeter lymph nodes were present in the periportal area and retroperitoneum (Figure, parts a and c). The appearance of the liver and spleen was normal (Figure, part a). No other abnormalities were identified in the abdomen.
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Figure a: Transverse contrast material–enhanced CT images of the abdomen in the portal venous (a, b, d) and late arterial (c) phases. In a, the appearance of the liver and spleen is normal, but periportal lymph nodes (arrows) can be seen. In b, increased attenuation of the mesentery (ie, the misty mesentery) (white arrow) and soft-tissue nodules (black arrows) along the superior mesenteric vessels are shown. Subcentimeter retroperitoneal lymph nodes (arrowheads) are also shown. In c, the misty mesentery (white arrows) and soft nodules (black arrow) are seen. Note that fat (white arrowheads) immediately adjacent to mesenteric vessels along the long axis is preserved. On cross-section CT images, this appearance is referred to as the fat ring sign. Retroperitoneal lymph nodes (black arrowheads) are shown. In d, prominent nodules (arrows) surround mesenteric vessels. Soft-tissue stranding (arrowheads) is shown anterior to the inferior vena cava and aorta.
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Figure b: Transverse contrast material–enhanced CT images of the abdomen in the portal venous (a, b, d) and late arterial (c) phases. In a, the appearance of the liver and spleen is normal, but periportal lymph nodes (arrows) can be seen. In b, increased attenuation of the mesentery (ie, the misty mesentery) (white arrow) and soft-tissue nodules (black arrows) along the superior mesenteric vessels are shown. Subcentimeter retroperitoneal lymph nodes (arrowheads) are also shown. In c, the misty mesentery (white arrows) and soft nodules (black arrow) are seen. Note that fat (white arrowheads) immediately adjacent to mesenteric vessels along the long axis is preserved. On cross-section CT images, this appearance is referred to as the fat ring sign. Retroperitoneal lymph nodes (black arrowheads) are shown. In d, prominent nodules (arrows) surround mesenteric vessels. Soft-tissue stranding (arrowheads) is shown anterior to the inferior vena cava and aorta.
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Figure c: Transverse contrast material–enhanced CT images of the abdomen in the portal venous (a, b, d) and late arterial (c) phases. In a, the appearance of the liver and spleen is normal, but periportal lymph nodes (arrows) can be seen. In b, increased attenuation of the mesentery (ie, the misty mesentery) (white arrow) and soft-tissue nodules (black arrows) along the superior mesenteric vessels are shown. Subcentimeter retroperitoneal lymph nodes (arrowheads) are also shown. In c, the misty mesentery (white arrows) and soft nodules (black arrow) are seen. Note that fat (white arrowheads) immediately adjacent to mesenteric vessels along the long axis is preserved. On cross-section CT images, this appearance is referred to as the fat ring sign. Retroperitoneal lymph nodes (black arrowheads) are shown. In d, prominent nodules (arrows) surround mesenteric vessels. Soft-tissue stranding (arrowheads) is shown anterior to the inferior vena cava and aorta.
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Figure d: Transverse contrast material–enhanced CT images of the abdomen in the portal venous (a, b, d) and late arterial (c) phases. In a, the appearance of the liver and spleen is normal, but periportal lymph nodes (arrows) can be seen. In b, increased attenuation of the mesentery (ie, the misty mesentery) (white arrow) and soft-tissue nodules (black arrows) along the superior mesenteric vessels are shown. Subcentimeter retroperitoneal lymph nodes (arrowheads) are also shown. In c, the misty mesentery (white arrows) and soft nodules (black arrow) are seen. Note that fat (white arrowheads) immediately adjacent to mesenteric vessels along the long axis is preserved. On cross-section CT images, this appearance is referred to as the fat ring sign. Retroperitoneal lymph nodes (black arrowheads) are shown. In d, prominent nodules (arrows) surround mesenteric vessels. Soft-tissue stranding (arrowheads) is shown anterior to the inferior vena cava and aorta.
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DISCUSSION
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The radiographic findings of mesenteric nodules and mesenteric stranding associated with retroperitoneal adenopathy represent incidental findings in an asymptomatic patient who underwent CT to detect morphologic evidence of liver cirrhosis and possible hepatocellular carcinoma related to hepatitis C. Therefore, the diagnosis was mainly based on CT findings. In this case, the differential diagnosis included lymphoma, sclerosing mesenteritis, chronic hepatitis C, metastatic disease, infectious inflammatory disease, and noninfectious inflammatory conditions.
The correct diagnosis was lymphoma of the mesentery. The clue to this diagnosis was the prominent mesenteric lymphadenopathy associated with retroperitoneal lymph nodes. Percutaneous fine-needle aspiration biopsy of the mesenteric nodules was performed after initial CT scanning. Cytologic examination and flow cytometry findings allowed us to confirm a diagnosis of follicular lymphoma, which is the most common subtype of non-Hodgkin lymphoma. The cells demonstrated small-cleaved morphology. Flow cytometry showed a monoclonal population of B cells and 60% of gated events expressing CD10, CD19, or CD20, with a 
to 
ratio of 31:1. CD5 and CD23 were not detected.
Lymphoma is the most common cause of mesenteric masses (1). Most cases of mesenteric lymphadenopathy are associated with non-Hodgkin lymphoma rather than with epithelial tumors (2,3). Mesenteric involvement is the predominant finding in 4%–5% of patients with Hodgkin lymphoma and in 30%–50% of patients with non-Hodgkin lymphoma (4,5). Mesenteric masses due to lymphoma may involve the small bowel by means of direct extension; they may also indirectly affect the small bowel by means of displacement due to mass effect. Although mesenteric involvement may be an isolated finding, it usually accompanies more systemic involvement (6).
Lymphoma of the mesentery can range in size (from small to bulky masses) and shape (from round or oval soft-tissue opacities to irregular masses) (4,7). On CT images, lymphoma of the mesentery can appear as multiple round, mildly enhancing, homogeneous masses that often surround mesenteric arteries and veins, as in this case. Lymphoma can grow so large that it encases the mesenteric vasculature without causing ischemia (8). The sandwich sign is created by the lobulated, confluent mesenteric soft-tissue masses that resemble two halves of a sandwich and the tubular structures of the mesenteric vessels and perivascular fat that resemble the sandwich filling (7,9). This sign usually is seen in patients with lymphoma of the mesentery; however, posttransplantation lymphoproliferative disorder can have a similar CT appearance (9). Lymphoma of the mesentery also can appear on CT images as a large, lobulated cake-like heterogeneous mass with areas of low attenuation representing necrosis that displaces bowel loops. Lymphoma of the mesentery can be associated with increased attenuation in the mesenteric fat (Figure, part b) that resembles the appearance of misty fat seen in patients with mesenteric panniculitis. However, this ill-defined infiltration of the mesenteric fat is more commonly seen in patients with lymphoma after they have undergone chemotherapy.
The CT findings of increased attenuation of the mesentery (the so-called misty mesentery) (10), soft-tissue nodules along the superior mesenteric vessels, and preservation of fat immediately adjacent to the mesenteric vessels (the so-called fat ring sign) (11,12) could indicate a diagnosis of sclerosing mesenteritis (subtype, mesenteric panniculitis). Sclerosing mesenteritis is a rare disease consisting of chronic mesenteric inflammation, fat necrosis, and fibrosis that affects the root of the mesentery (11,13). If the inflammatory component is predominant, sclerosing mesenteritis is often referred to as mesenteric panniculitis. However, if the fibrotic component is predominant, sclerosing mesenteritis is often referred to as retractile mesenteritis. Clinical manifestations of sclerosing mesenteritis vary from no symptoms to abdominal pain, intestinal obstruction, ischemia, abdominal mass, weight loss, pyrexia, and/or diarrhea (8,14).
The CT appearance of sclerosing mesenteritis can mimic that of lymphoma, as CT images obtained in patients with sclerosing mesenteritis may show nodular soft-tissue opacities in the mesentery. Additionally, the presence of a fat ring sign (as described previously) and a tumoral pseudocapsule (seen as a peripheral band of soft-tissue attenuation that limits the inflammatory activity in the normal mesentery) indicates a diagnosis of mesenteric panniculitis (11). While only the fat ring sign was observed in this case, these two signs are relatively nonspecific and can be observed in patients with other disorders, including lymphoma (12). Mesenteric panniculitis was reported to coexist with malignancy (mainly lymphoma) in 15% of patients by Kipfer et al (15) and in 69% of patients by Daskalogiannaki et al (14). The nature of the association between mesenteric panniculitis and lymphoma remains unexplained (15,16).
When sclerosing mesenteritis is suspected because of clinical or imaging findings, biopsy is needed for definitive diagnosis. Although results from percutaneous biopsies may lead to the correct diagnosis, surgical excisional biopsies often are needed for complete histologic assessment. Because of the association of sclerosing mesenteritis with infectious and malignant processes, it is imperative to exclude any such underlying disease in any patient suspected of having sclerosing mesenteritis (8). Sclerosing mesenteritis is only rarely associated with retroperitoneal adenopathy (3,5,8,11); therefore, it is an unlikely diagnosis in this case.
Chronic hepatitis C could manifest with lymph nodes in the periportal, portocaval, or peripancreatic areas (17). Prominent mesenteric disease in the presence of retroperitoneal adenopathy below the celiac axis is not compatible with changes due to hepatitis C.
Metastatic diseases—such as colon carcinoma; breast, ovarian, or lung cancer; carcinoid tumor; or melanoma—can be excluded because the nodal distribution is more localized and the nodal enlargement is not as pronounced as that seen in patients with lymphoma (1). Metastatic adenopathy in the mesentery is usually an expression of widespread disease of a known primary tumor. This was not the case in this patient.
Several infectious inflammatory conditions—such as tuberculosis, atypical mycobacterial infection, and Whipple disease—can produce mesenteric lymphadenopathy that can mimic lymphoma or metastatic disease (18,19). Lymph nodes in these patients usually have a multilocular appearance or appear as rim-enhancing nodules with central caseating areas of necrosis. Both of these forms frequently are associated with lesions in the spleen and liver. Usually, inflammatory adenopathy does not coalesce, as lymphoma tends to do. In cases of abdominal tuberculosis, the terminal ileum and cecum may be thickened and the peritoneal lining may be enhanced. Whipple disease also should be considered when low-attenuation nodules in the mesentery are observed. This disease is a rare condition caused by the gram-positive bacillus Trophermyma whipplei. It is seen predominantly in young white male patients, and it is associated with thickened small-bowel loops. Mesenteric adenopathy, the absence of any symptoms, and the lack of associated findings are not compatible with any of these infectious inflammatory conditions.
Noninfectious inflammatory conditions—such as celiac sprue, Crohn disease, and systemic mastocytosis—may produce mesenteric adenopathy; however, all these conditions are associated with symptoms and many other changes that were not seen in this patient. Typical radiologic features of celiac sprue include dilatation of the small intestine with thickening or obliteration of the mucosal folds, straightening of the valvulae conniventes, hyposplenism, ascites, and mesenteric low-attenuation nodes (20). Celiac sprue can be associated with lymphoma of the intestine, which usually is seen as nodular bowel wall thickening. Crohn disease appears on CT cross-sectional images as small-bowel disease, large-bowel disease, or both, with thickening of the bowel wall, skip areas, bowel stenosis, fistulae, fibrofatty proliferation, and mesenteric nodes (19). Common abdominal imaging findings associated with systemic mastocytosis are hepatosplenomegaly; retroperitoneal, periportal, or mesenteric adenopathy; thickening of the omentum and mesentery; dilated small-bowel loops with fine nodules; and ascites (18). None of these noninfectious inflammatory conditions manifest with mesenteric adenopathy and stranding alone; therefore, none are likely diagnoses.
In this case, the imaging findings of mesenteric soft-tissue nodules associated with mesenteric stranding and retroperitoneal lymph nodes, coupled with an absence of symptoms, made lymphoma the most likely diagnosis.
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FOOTNOTES
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2 Current address: Department of Radiology, Bumrungrad International Hospital, Bangkok, Thailand 
| Part one of this case appeared 4 months previously and may contain larger images.
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References
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- Kipfer RE, Moertel CG, Dahlin DC. Mesenteric lipodystrophy. Ann Intern Med 1974;80:582–588.[Medline]
- Seo BK, Ha HK, Kim AY, et al. Segmental misty mesentery: analysis of CT features and primary causes. Radiology 2003;226:86–94.[Abstract/Free Full Text]
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Congratulations to the 19 individuals and one resident group that submitted the most likely diagnosis (lymphoma of the mesentery) for Diagnosis Please, Case 107. The names and locations of the individuals and resident group, as submitted, are as follows:
Individual responses
- Jason Brandon Ashley, MD, London, Ontario, Canada
- Manuela Certo, MD, Santo Tirso, Portugal
- Manoel de Souza Rocha, MD, São Paulo, Brazil
- Seyed A. Emamian, MD, PhD, Rockville, Md
- Yuusuke Hirokawa, MD, Kyoto City, Japan
- Venkata Subbaiah Katabathina, Hyderabad, India
- Michael Beckett Martin, MD, Austin, Tex
- Uma Mahesh Matapathi, Hyderabad, India
- Utaroh Motosugi, MD, Yamanashi, Japan
- Sugoto Mukherjee, MBBS, Charlottesville, Va
- Mizuki Nishino, MD, Boston, Mass
- Albert Nizzero, MD, Sudbury, Ontario, Canada
- Michael James Shepard, MD, Palo Alto, Calif
- Taro Shimono, MD, Sakai, Osaka, Japan
- Thomas Patrick Sullivan, MD, Seattle, Wash
- Özgür Tosun, Ankara, Turkey
- Dengbin Wang, Shanghai, China
- Jeffrey H. Zapolsky, MD, Oshkosh, Wis
- Xiangwu Zheng, Wenzhou, China
Resident group responses
- Virginia Commonwealth University Radiology Residents, Richmond, Va
TOP
HISTORY
IMAGING FINDINGS
