Radiography
Findings
Findings on supine and upright abdominal radiographs are often normal. Nonspecific findings include a regional ileus or evidence of bowel wall thickening in the right lower quadrant (see Image 2).
Supine abdominal radiograph shows a mild localized ileus and suggests nodular thickening of the terminal ileum.
Degree of Confidence
Plain radiographic findings can never indicate a specific diagnosis in mesenteric adenitis, but they can occasionally confirm an alternative diagnosis. Cross-sectional imaging may be indicated regardless of the plain radiographic findings.
Computed Tomography
Findings
Diagnostic features include enlarged mesenteric lymph nodes, with or without associated ileal or ileocecal wall thickening, in the setting of a normal appendix.4 Rao et al specified the criterion of 3 or more nodes with a short-axis diameter of at least 5 mm, clustered in the right lower quadrant (see Images 3-4).17 Lymph nodes are generally larger, more numerous, and more widely distributed in mesenteric adenitis than in appendicitis. Ileal thickening is diagnosed when the wall is thicker than 3 mm over at least 5 cm of the bowel despite bowel lumen opacification and distention (see Image 5).
Abdominal CT scan shows a cluster of enlarged nodes in the right lower quadrant.
Mesenteric thickening associated with right lower quadrant adenopathy.
A thickened ileum and cecum and a normal appendix are depicted adjacent to an enlarged lymph node in this patient with mesenteric adenitis and terminal ileocolitis.
Degree of Confidence
In the prospective study by Rao et al, none of the 18 patients with the aforementioned CT criteria had surgical or clinical evidence of appendicitis, whereas appendicitis was correctly diagnosed in 56.17 Further imaging is generally not indicated, although a definitive diagnosis might not be made in a case with equivocal findings until laparotomy performed for the evaluation of appendicitis reveals negative findings.
False Positives/Negatives
Nonopacified bowel may be mistaken for enlarged lymph nodes, especially in thin patients or small children. Bowel wall thickness is difficult to determine in this setting.
Ultrasonography
Typical sonographic appearance of a normal appendix.
Typical sonographic appearance of a lymph node.
Lymph node clustering in the right lower quadrant.
Distended appendix with an appendicolith in acute appendicitis.
Reactive lymph nodes in acute appendicitis.
Color sonogram demonstrates nodal hyperemia.
Spectral Doppler sonogram demonstrates nodal hyperemia.
Circumferential thickening of the ileal wall and associated nodal enlargement.
Findings
In patients with fever, abdominal tenderness, and a normal appendix, adenopathy that predominantly involves but is not limited to the right lower quadrant suggests the diagnosis (see Images 6-7). Usually, 5 or more nodes are present and are often clustered (see Image 8 ). Nodal tenderness in response to transducer pressure is typical. Nodes are more rounded and hypoechoic than normal. Abnormal nodes have a short-axis diameter of at least 5 mm, and the diameter can exceed 1 cm. The nodes are typically larger and more numerous with mesenteric adenitis than with appendicitis (see Images 9-10).16
The demonstration of hyperemia within the node and surrounding mesentery with Doppler imaging is variably reported (see Images 11-12). Other findings include intestinal hyperperistalsis, which is seldom observed in appendicitis; nodular or circumferential thickening of the bowel wall; mesenteric thickening; fluid-filled loops; cecal involvement; and free fluid (see Image 13).18 Occasionally, a fluid-filled appendix is seen, but the lumen is readily compressible.5
Increased echogenicity of intra-abdominal fat has been reported as a nonspecific marker for right lower quadrant inflammatory disease, seen in appendicitis, mesenteric adenitis, and other illnesses.19 Similarly, increased echogenicity of renal parenchyma has been noted in children with mesenteric adenitis, as well as appendicitis and other acute illness; it is a transient feature and does not necessarily indicate renal disease.18
Degree of Confidence
Although nodal size and number are generally greater in mesenteric adenitis than in appendicitis, overlap does occur. In Simonovsky's large series of 609 patients, 426 had appendicitis, and 81 had mesenteric adenitis.20 The inflamed appendix was missed in 2 of the latter cases. Puylaert stated that in adult patients with right lower quadrant pain in whom the sole findings are enlarged mesenteric lymph nodes, the risk of appendicitis is 64%.6 Therefore, the diagnosis of mesenteric adenitis is hazardous when the appendix is not visualized; correlative CT may be beneficial in this setting.
In mesenteric adenitis and lymphoma, the size, shape, distribution, and Doppler imaging characteristics of the lymph nodes overlap considerably, although the clinical context is useful in narrowing the differential diagnosis.21
False Positives/Negatives
Mesenteric lymph nodes that exceed the normal size threshold may be visualized in the absence of disease, although these are usually nontender.
Nuclear Imaging
Findings
Nuclear scintigraphy is seldom useful in this setting. A single case report describes abnormal white-cell localization in the nasopharynx, cervical lymph nodes, and right lower quadrant during imaging with indium-111–labeled white blood cells in a 4-year-old boy with fever, pharyngitis, and abdominal pain.22
More on Mesenteric Adenitis |
| Overview: Mesenteric Adenitis |
 Imaging: Mesenteric Adenitis |
| Follow-up: Mesenteric Adenitis |
| Multimedia: Mesenteric Adenitis |
| References |
| Further Reading |
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References
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Frisch M, Pedersen BV, Andersson RE. Appendicitis, mesenteric lymphadenitis, and subsequent risk of ulcerative colitis: cohort studies in Sweden and Denmark. BMJ. Mar 9 2009;338:b716. [Medline]. [Full Text].
Schulte B, Beyer D, Kaiser C, et al. Ultrasonography in suspected acute appendicitis in childhood-report of 1285 cases. Eur J Ultrasound. Dec 1998;8(3):177-82. [Medline].
Borgia G, Ciampi R, Nappa S, et al. Tuberculous mesenteric lymphadenitis clinically presenting as abdominal mass: CT and sonographic findings. J Clin Ultrasound. Sep 1985;13(7):491-3. [Medline].
Puylaert JB. Mesenteric adenitis and acute terminal ileitis: US evaluation using graded compression. Radiology. Dec 1986;161(3):691-5. [Medline].
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Zippi M, Colaiacomo MC, Marcheggiano A, et al. Mesenteric adenitis caused by Yersinia pseudotubercolosis in a patient subsequently diagnosed with Crohn's disease of the terminal ileum. World J Gastroenterol. Jun 28 2006;12(24):3933-5. [Medline].
Black RE, Slome S. Yersinia enterocolitica. Infect Dis Clin North Am. Sep 1988;2(3):625-41. [Medline].
Hervas JA, Alberti P, Bregante JI, et al. Chronic intussusception associated with Yersinia enterocolitica mesenteric adenitis. J Pediatr Surg. Dec 1992;27(12):1591-2. [Medline].
Quillin SP, Siegel MJ. Appendicitis in children: color Doppler sonography. Radiology. Sep 1992;184(3):745-7. [Medline].
Blattner RJ. Acute mesenteric lymphadenitis. J Pediatr. Mar 1969;74(3):479-81. [Medline].
Garcia-Corbeira P, Ramos JM, Aguado JM, Soriano F. Six cases in which mesenteric lymphadenitis due to non-typhi Salmonella caused an appendicitis-like syndrome. Clin Infect Dis. Jul 1995;21(1):231-2. [Medline].
Hayden CK Jr. Ultrasonography of the acute pediatric abdomen. Radiol Clin North Am. Jul 1996;34(4):791-806. [Medline].
American College of Radiology. ACR Appropriateness Criteria® right lower quadrant pain. National Guideline Clearinghouse. Available at http://www.guideline.gov/summary/summary.aspx?doc_id=8593&nbr=004780. Accessed May 26, 2009.
Simanovsky N, Hiller N. Importance of sonographic detection of enlarged abdominal lymph nodes in children. J Ultrasound Med. May 2007;26(5):581-4. [Medline].
Rao PM, Rhea JT, Novelline RA. CT diagnosis of mesenteric adenitis. Radiology. Jan 1997;202(1):145-9. [Medline]. [Full Text].
Wiersma F, Toorenvliet BR, Ruige M, Holscher HC. Increased echogenicity of renal cortex: a transient feature in acutely ill children. AJR Am J Roentgenol. Jan 2008;190(1):240-3. [Medline]. [Full Text].
Lee MW, Kim YJ, Jeon HJ, Park SW, Jung SI, Yi JG. Sonography of acute right lower quadrant pain: importance of increased intraabdominal fat echo. AJR Am J Roentgenol. Jan 2009;192(1):174-9. [Medline].
Simonovsky V. Ultrasound in the differential diagnosis of appendicitis. Clin Radiol. Nov 1995;50(11):768-73. [Medline].
Al-Kawas FH, Murgo A, Foshag L, Shiels W. Lymphadenopathy in celiac disease: not always a sign of lymphoma. Am J Gastroenterol. Mar 1988;83(3):301-3. [Medline].
Achong DM, Oates E, Harris B. Mesenteric lymphadenitis depicted by indium 111-labeled white blood cell imaging. J Pediatr Surg. Dec 1993;28(12):1550-2. [Medline].
Ikeda Y, Ikeda Y, Nakai T, Sano K, Ueda W, Aoki T, et al. A case of mesenteric lymphadenitis with long-acting symptom, showing marked response to corticosteroid. Nippon Shokakibyo Gakkai Zasshi. Sep 2007;104(9):1371-6. [Medline].
Further Reading
Related eMedicine topics
Mesenteric Lymphadenitis
Yersinia Enterocolitica
Yersinia Enterocolitica Infection
Campylobacter Infections
Keywords
mesenteric adenitis, mesenteric lymphadenitis, acute ileitis, appendicitis, lymphoma
