Multi-system inflammatory syndrome in a child with Crohn's disease- a diagnostic dilemma

Post-covid multisystem inflammatory syndrome in children (MIS-C) can cause life-threatening inflammation in children, particularly in those with underlying conditions like Crohn's disease (CD). The overlap of symptoms between CD flares and MIS-C can create diagnostic and therapeutic challenges, necessitating high-level clinical suspicion and aggressive management when both conditions coexist. We present a 14-year-old boy, with a 3-year history of CD, who presented with diarrhea, abdominal pain, and weight loss. Investigations revealed anemia, thrombocytosis, hypoalbuminemia, and elevated inflammatory markers and fecal calprotectin. He was treated with methylprednisolone and methotrexate. On day 25 of admission, he developed altered sensorium, inability to ambulate, and hypoxia. He was found to have left ventricular dysfunction, non-hepatic hyperammonemia and cerebral sinus thrombosis. Work-up revealed a pro-inflammatory state with elevated serum ferritin, interleukin-6, d-dimers and positive anti-Covid IgG, and led to the diagnosis of MIS-C overlapping with CD flare. He was treated with intravenous immunoglobulin and recovered.