Mesenteric Adenitis

A valued follower of our prolific blog has requested for “a rundown on the mesenteric adenitis in children.” So here it is.

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- Ultrasound Connection

Stephanie Doniger, MD, RDMS, FAAP, FACEPMesenteric Adenitis

by Stephanie J. Doniger MD RDMS FAAP FACEP

Background

Abdominal pain is one of the most frequent presenting complaints of children to the emergency department. Mesenteric adenitis, or lymphadenitis is commonly encountered when evaluating a child presenting with acute abdominal pain.  Mesenteric adenitis, represents the inflammation of abdominal lymph nodes, and may be present in the ileo-cecal and/or para-aortic regions. The most common location is in the right lower quadrant (Vayner, 2003). The peak incidence is 10 years of age. There are varying etiologies, but most commonly due to Yersinia, Staphylococcus, Salmonella, Streptococcus, and various mycobacteria and viruses. Enlarged abdominal lymph nodes have also been found in children with recurrent abdominal pain and acute gastroenteritis.

There is some disagreement in the radiology literature regarding the sonographic criteria for the diagnosis of mesenteric adenitis. While asymptomatic children may have the presence of enlarged abdominal lymph nodes, they are generally 5mm or less. Those with acute abdominal pain due to mesenteric adenitis, have the presence of lymph nodes greater than 10 mm (Simanovsky, 2007).

US Technique

The high-frequency (5-10 MHz), linear transducer is utilized. The technique is the same as for the evaluation for appendicitis. Start at the point of maximal tenderness, or at McBurney’s point, in the right lower quadrant. Look for the landmarks of the psoas muscle and the adjacent iliac vessels. The appendix generally should lie on top of the psoas muscle, but may be located medially, laterally, or retro-cecally. Use the graded compression technique for better visualization. It may be helpful to utilize color Doppler to distinguish lymph nodes from blood vessels. Suspected lymph nodes should be measured in two dimensions: the short-axis and the long-axis.

Ultrasound Findings

Look for evidence of appendicitis:  a tubular, non-compressible structure measuring greater than 6 mm. Lymph nodes are also non-compressible, but elliptical or circular in shape. The often appear hypoechoic but have consistent and symmetric echotexture throughout the structure (in contrast to an abscess). In the radiology literature, lymph nodes measured in their short-axis of greater than 5 mm is the criteria for the sonographic diagnosis of mesenteric adenitis. Once study (Simanovsky, 2007) suggested that lymph nodes with measurements greater than 10 mm should be diagnostic for mesenteric adenitis, since they found many asymptomatic children with lymph nodes measuring 5 mm.

Hypoecoic Circle
Figure 1. Right lower quadrant ultrasound performed in the evaluation of a child with acute abdominal pain. This hypoechoic circular structure was visualized, in addition to a normal appendix.

Importance

Children often present with acute abdominal pain. Mesenteric adenitis can mimic acute appendicitis, ovarian torsion, intussusception, and other causes of an acute abdomen. Often ultrasound examinations are performed in order to assess for the presence of these etiologies, especially for appendicitis. Mesenteric lymphadenitis is often found, and may be an alternative cause of right lower quadrant pain. When a normal appendix is visualized in addition to enlarged lymph nodes, one can confidently diagnose mesenteric adenitis as the etiology of a child’s acute abdominal pain. Children may briefly need pain control or fluid hydration during the acute process. But ultimately, this is a benign, self-limiting condition that does not require medical or surgical intervention.

References

Macari, M., Hines, J., Balthazar, E., et al. Mesenteric adenitis: CT diagnosis of primary versus secondary causes, incidence, and clinical significance in pediatric and adult patients. Am J Roentgenol  2002; 178(4): 853-858.

Mason, JD. The evaluation of acute abdominal pain in children. Emerg Med Clin North Am 1996; 14(3): 629-643.

Schupp, C.J., Klingmuller, V., Strauch, K., et al. Typical signs of acute appendicitis in ultrasonography mimicked by other diseases? Pediatr Surg Int 2010; 26: 697-702.

Simanovsky, N., Hiller, N.  Importance of sonographic detection of enlarged abdominal lymph nodes in children. J Ultrasound Med 2007; 26: 581-584.

Vayner, N., Coret, A., Polliack, G., et al. Mesenteric lymphadenopathy in children examined by US for chronic and/or recurrent abdominal pain. Pediatr Radiol 2003; 33: 864-867.

Watanabe, M., Ishii, E., Hayashida, Y., et al. Evaluation of abdominal lymphadenopathy in children by ultrasonography. Pediatr Radiol 1997; 27(11): 860-864.

 

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