During a busy shift in the emergency department, while on your rotation as a student, you pick up the chart for a 10 year old male with one day of abdominal pain. Despite this being your eighth rotation, you take a deep breathe because you know that pediatric patients can be tricky.

As you enter the room, the patient’s parent allows you to take the history. You discover the onset was yesterday. The timing is continuous. It is worse with food, better with rest. The patient describes his pain as achy, sharp, and localized to the right lower quadrant, “really bad” in nature, and worse since awakening this morning.

Associated symptoms include nausea, vomiting and fatigue. The patient has been healthy otherwise. No past medical history. No family history. No new foods. No new stress at school.

Your diagnostic skills start to hone in and you start to consider this case as a slam dunk. As the parent talks to you, your mind continually screams APPENDICITIS. It seems very obvious.

The patient’s vitals include a pulse of 92, respirations of 14, blood pressure of 110/72, and a temperature of 100.1 F. On exam, he appears uncomfortable but non-toxic. His HEENT exam is unremarkable, his lungs are clear, his heart is regular.

When you press on his abdomen, he is non-tender except for the right lower quadrant. He does not seem to rebound or guard when you deeply palpate his abdomen. Next, you perform each of the special signs you learned during your History and Physical exam course.

You begin by pressing on his left lower quadrant, asking if he has any pain in the right lower quadrant. He says no and you deduct a negative Rovsing’s sign. Next, you ask him to lay on his back, flexing his hip as you apply pressure downward on his leg. He yelps out in pain and you find a positive psoas sign. Finally, you assume control of the patient’s right leg and passively internally rotate and flex his hip. There is no pain, so you end your abdominal exam with a negative obturator sign.

As you leave the room to consult with your preceptor, you gather your thoughts. You start to think about your plan.Labs, IV fluids, CT scan, possible surgery consult depending on findings. You’re fairly positive you have nailed an acute appendicitis. After your presentation, your shift is over, and you go home to read up on the day’s cases, eager to find out how your patient did, as his CT scan is not yet back upon your departure.

Upon your arrival for your next shift, you discuss with your preceptor. You ask, “What room is our patient from last night in, how did the surgery go”, confident in the acute appendicitis diagnosis you made.

Your preceptor smiles and says, “We sent him home”. Flabbergasted, you assume he is joking, but when he says, “Read up on what can present like an appendicitis and give me a presentation tomorrow about it”.

Mesenteric adenitis occurs when the mesenteric lymph nodes, which are located in the abdomen, become enflamed. This is a benign etiology that can be associated as “mimicking” appendicitis (Walsh and Trivedi, 2016).

The disorder is fairly common, but frequently misdiagnosed, making it difficult to estimate the incidence. It is thought that up to 20% of patients on the table for an appendectomy actually have mesenteric adenitis.

In adults, there is more commonly a secondary mesenteric adenitis, which can be reactionary related to diverticulitis, Crohn’s disease, infectious origin or inflammatory in origin.

In children, the most common etiology is infectious. A classic association is that mesenteric adenitis is most commonly caused by Yersinia enterocolitica but other pathogens such as Staphlyococcus, streptococcus, and E. Coli are also culprits.

In the history, there may be a recent upper respiratory infection or previous pharyngitis diagnosis. Under cooked pork can point to Yersinia as a causative pathogen.

As discussed in our case study, there is usually onset of vague nausea, vomiting, and abdominal discomfort. Abdominal pain may be periumbilical or localized to the right lower quadrant. Malaise, diarrhea, fever, loss of appetite are also common, but certainly are very non-specific.

The exam in patients with mesenteric adenitis may show fever, abdominal tenderness, lymphadenopathy, or even a toxic appearance depending on the course.

The workup for mesenteric adenitis includes basic lab work. A CBC may show a mild leukocytosis, depending on the course of infection. A CMP can show dehydration.

The decision to use advanced imaging should be discussed with patients, as radiation is not without risks. A CT scan of the abdomen and pelvis will show enlargement and inflammation of the mesenteric lymph nodes. The differentiating feature is that mesenteric adenitis should have a normal appendix. Ultrasound is a reasonable choice to try to avoid radiation, but a CT may be necessary.

The treatment for mesenteric adenitis is largely supportive. In patients with signs of dehydration, fluid balance should be restored. Electrolyte disturbances can be corrected. In patients with moderate to severe illness with signs of systemic infection, broad spectrum anti-biotics, IV fluids are utilized to attain stability. Antibiotics are usually unnecessary, as the disease is largely self-limited.

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