Mesenteric adenitis

Mesenteric adenitis refers to acute or chronic inflammation of the mesenteric lymph nodes.

Mesenteric adenitis (or lymphadenitis) is a common cause of abdominal pain in children. There is usually acute or chronic self-limiting inflammation of the mesenteric lymph nodes that leads to enlargement and associated pain.

It is most commonly secondary to a viral infection. It can be difficult to differentiate mesenteric adenitis from acute appendicitis as the inflamed nodes are typically located in the right iliac fossa. In some cases, it may be necessary to proceed to an operation (e.g. laparoscopy) to be able to differentiate between the two.

Mesenteric adenitis commonly affects children under 16 years old, but the exact prevalence is unknown and commonly mistaken for other diagnoses. Cases are increasing, which is thought to be due to the increased use of ultrasound.

Mesenteric adenitis is commonly due to viruses.

Mesenteric adenitis often follows viral or bacterial gastroenteritis with a range of organisms implicated:

• Viruses: coxsackieviruses, rubeola virus, adenovirus
• Bacteria: Yersinia species, Streptococcus, Staphylococcus, Escherichia coli,

These organisms are usually ingested orally and then reach the mesenteric lymph nodes via the gastrointestinal lymphatic system and undergo replication. This leads to local inflammatory responses, lymph node enlargement, and subsequent abdominal pain with systemic symptoms.

Mesenteric adenitis commonly causes abdominal pain in the right iliac fossa.

The hallmark of mesenteric adenitis is abdominal pain that is commonly located in the right iliac fossa, which makes it difficult to differentiate from appendicitis.

Symptoms

• Often preceding illness: upper respiratory tract infection or gastroenteritis
• Abdominal pain: may be generalised or localised to the right iliac fossa
• Fever
• Nausea/vomiting
• Diarrhoea

Signs

• Fever
• Right lower quadrant tenderness and guarding
• Erythematous pharynx
• Peripheral lymphadenopathy (seen in 20%)

Abdominal ultrasound is normally the investigation of choice for suspected mesenteric adenitis.

Mesenteric adenitis is diagnosed using abdominal ultrasound. Ultrasound is excellent at excluding alternative causes of abdominal pain such as appendicitis. Mesenteric adenitis is indicated by the presence of enlarged abdominal lymph nodes in the right lower quadrant. However, it is also important to show a normal appearing appendix during the ultrasound.

In some cases, it may be very difficult to differentiate between mesenteric adenitis and appendicitis. This may require patients to undergo a diagnostic laparoscopy to directly visualise the appendix and mesentery.

Other investigations may be requested depending on the presentation and severity of symptoms such as blood tests or urinalysis.

Mesenteric adenitis is usually a self-limiting illness that resolves within four weeks.

The principal treatment of mesenteric adenitis is adequate hydration and analgesia. Symptoms, such as abdominal pain, will usually resolve within 1-4 weeks. If there is any concern, patients may require hospital admission for intravenous fluids and observation.