MIS-CM imicking Acute Appendicitis

ABSTRACT

Introduction: Abdominal pain is one of the most common complaints seen in the pediatric acute care setting. SARS-CoV-2 disease in children includes a hyperinflammatory syndrome called Multisystem Inflammatory Syndrome in Children (MIS-C). Gastrointestinal symptoms are most common in pediatric acute SARS-CoV-2 infection as well as in MIS-C. Case Description A 13- year-old female presented with diffuse lower abdominal pain for 3-days. Pain was 10/10 in intensity, worsened with movement, and had associated constipation, anorexia, nausea, and vomiting. Exam showed an ill-appearing female with labile vitals and generalized lower abdominal tenderness with good bowel sounds. Ultrasound suggested features of acute appendicitis but a follow-up CT did not visualize the appendix. She was admitted to the inpatient unit after routine screening revealed positive SARS-CoV-2 antibody but negative PCR. She received IV fluid bolus, narcotic analgesics, and ampicillin-sulbactam preoperatively. Within hours, she spiked high-grade fevers (101.4F), sustained hypotension, and tachycardia with concern for sepsis secondary to a possible ruptured appendix. She underwent emergency diagnostic laparoscopy which revealed bile-tinged fluid in the lower quadrant, a mildly inflamed appendicular tip without perforation, and thickened mesenteric nodes within the inflamed distal ileum. Intra-operatively, she had persistent hypotension requiring fluid boluses and vasopressors. Her admission labs revealed elevated inflammatory markers, deranged coagulation profile, and elevated cardiac enzymes. Her differential diagnosis was then revised to include MIS-C and severe sepsis. Antibiotic coverage was broadened to Vancomycin and Meropenem. An Echocardiogram showed mitral regurgitation with moderately to severely decreased right and left ventricular systolic dysfunction with an ejection fraction of 32.8% The patient was then transferred to the pediatric cardiac critical unit where she received treatment with IVIG, steroids, and anticoagulants. Her clinical status and lab studies improved with EF > 50%. She was discharged from the intensive care unit after 7 days and has had an uneventful follow-up. Discussion: Differential diagnosis for acute lower abdominal pain in an adolescent female is broad. Similar cases with predominant GI symptoms and later generalized multisystem involvement have been reported, however, most were managed conservatively. Two reports have been published on MIS-C presenting as acute appendicitis, but neither had significant cardiac involvement. Our patient's presentation can easily be confused with an acute surgical abdomen but the pathology report confirmed a congested appendix without any fecoliths supporting either inflammation or vasculitis as the cause for her presentation, which is in concordance with the hyperinflammatory state that has previously been described in patients presenting with a history of past SARS-CoV- 2 infections. Conclusion: MIS-C can mimic serious pediatric illnesses including sepsis, acute abdomen, and Kawasaki disease. Clinicians should have a low threshold for suspecting MIS-C, as prompt treatment can be lifesaving. Universal screening for COVID-19 infection with PCR and antibody tests can expedite the diagnostic evaluation of severely ill children. Showing reactive wall thickening of the cecum and small bowel loops (red arrow) and enlarged mesenteric lymph nodes (yellow arrow). The appendix could not be visualized here.