Introduction
Background
Mesenteric adenitis is a self-limited inflammatory process that affects the mesenteric lymph nodes in the right lower quadrant. Its clinical presentation mimics that of acute appendicitis. Until recently, the diagnosis was most frequently made when laparotomy performed to assess presumed appendicitis yielded negative findings; now, cross-sectional imaging is routinely applied in the examination of patients.
Pathophysiology
Mesenteric adenitis is most frequently caused by viral pathogens, but other infectious agents have been implicated, including Yersinia enterocolitica, Helicobacter jejuni, Campylobacter jejuni, and Salmonella or Shigella species.1,2,3 An association with streptococcal infections of the upper respiratory tract, particularly the pharynx, has been reported. In younger children and infants, concurrent ileocolitis may be present; this finding suggests that the lymph node involvement may occur in reaction to a primary enteric pathogen.
Related eMedicine topics:
Yersinia Enterocolitica Infection
Salmonella Infection
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Helical CT Evaluation of Acute Right Lower Quadrant Pain: Part I, Common Mimics of Appendicitis
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Frequency
United States
In 2 recent series involving patients with clinical symptoms suggestive of acute appendicitis, mesenteric adenitis was the most frequent alternative diagnosis; it was present in 8-12% of patients. In Europe and North America, the proportion of patients with Y enterocolitica infection who undergo appendectomy is 3.0-9.0%.
International
As an etiologic agent of mesenteric adenitis, Y enterocolitica is less common in developing nations than in other nations. In Europe and North America, the proportion of patients with Y enterocolitica infection who undergo appendectomy is 3.0-9.0%. In 2 small studies of children who underwent appendectomy in Bangladesh, Yersinia organisms were not found.
Mortality/Morbidity
Most cases are self-limited, although disease lasting longer than 2 weeks is common. With Yersinia ileocolitis, small-bowel disease may be severe, and gangrene and death have been reported. Children who undergo laparotomy for presumed appendicitis are at risk for surgical complications.
Race
No racial predilection is reported.
Sex
Two large published series provide no information about the sex ratio. The clinical differential diagnosis in patients with right lower quadrant pain is broader in girls, especially in adolescents in whom gynecologic pathology must be considered.
Age
Mesenteric adenitis can occur in adults, but it is most common in children and adolescents younger than 15 years. Associated enteric disease most often occurs in those younger than 5 years.4
Anatomy
Mesenteric lymph nodes are present near mesenteric vessels and between bowel loops. They normally appear flattened, ovoid, or disc-shaped, and they have a characteristic fatty central hilum and a solid peripheral cortex (see Image 1). Vessels enter and exit the node at the hilum and branch within the node in a fashion similar to that of the kidney. Normal mesenteric lymph nodes vary in size, but, in general, the short-axis diameter is 4 mm or shorter.
Presentation
Mesenteric adenitis is a self-limited condition characterized by fever, abdominal pain, nausea, and, occasionally, diarrhea. Pain and tenderness are often centered in the right lower quadrant, but they may be more diffuse than in appendicitis. The site of tenderness may shift when the patient's position changes, whereas the location of the tenderness tends to be fixed with appendicitis. Leukocytosis is common.
The diagnosis of mesenteric adenitis is one of exclusion; confirmation is based on a benign clinical course, and management is conservative.
Preferred Examination
Ultrasonography of the right lower quadrant with graded compression has been the mainstay of diagnosis in children.5 Recently, many centers have adopted CT as an alternate or, sometimes, the primary diagnostic modality in the setting of presumed appendicitis, especially in men and in those in whom visualization of the appendix may be compromised by their body habitus. Although the findings are frequently nonspecific, abdominal radiographs occasionally reveal findings and permit alternative diagnoses (eg, appendicoliths).
Limitations of Techniques
The normal appendix is sonographically occult in a significant subset of patients. When lymph node enlargement is detected on sonographic examination in these patients, excluding appendicitis as a cause of reactive adenopathy is difficult.6,7
In some centers, CT is performed for the evaluation of appendicitis without intravenous and/or oral contrast enhancement. This approach reduces the sensitivity of CT for bowel wall thickening and mesenteric adenopathy, especially in small children with a paucity of intraperitoneal fat.
With any imaging modality, the finding of lymph node enlargement as an isolated finding is nonspecific; it can be observed in association with several inflammatory processes. Occasionally, nodes exceeding the normal size threshold are observed in children who have no demonstrable disease.
Differential Diagnoses
Appendicitis
Crohn Disease
Sprue
Other Problems to Be Considered
Infectious gastroenteritis
Lymphoma
More on Mesenteric Adenitis |
 Overview: Mesenteric Adenitis |
| Imaging: Mesenteric Adenitis |
| Follow-up: Mesenteric Adenitis |
| Multimedia: Mesenteric Adenitis |
| References |
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References
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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].
Further Reading
Keywords
mesenteric lymphadenitis, acute ileitis, appendicitis, lymphoma
