Multisystem Inflammatory Syndrome Presenting as Early Acute Appendicitis.

An 11-year-old male presented to the pediatric emergency department with a one-day history of peri-umbilical pain with nausea, anorexia, and scant vomiting. On examination, he had moderate tenderness in the right upper quadrant with moderate guarding and rebound tenderness. Imaging showed concern for early acute appendicitis. The patient was admitted and underwent laparoscopic appendectomy. Despite the appendectomy, the patient continued to have fevers and abdominal pain. Four days after the initial presentation, the patient decompensated and was diagnosed with multisystem inflammatory syndrome. This case is interesting because the patient never met diagnostic criteria for multisystem inflammatory syndrome in children (MIS-C) prior to his decompensation. If a patient's symptoms continue or worsen despite seemingly appropriate management, the patient must be reassessed for other causes of pathology. Surgeons must have a high index of suspicion for MIS-C in patients with recent COVID-19 diagnoses, and this case demonstrates that MIS-C can present in phases and not all at once.