Abstract
INTRODUCTION: Multisystem inflammatory syndrome in children (MIS-C) is a rarely seen severe complication of coronavirus disease-2019 (COVID-19). Although fever is one of the indispensable symptoms, other infections should be considered in the differential diagnosis during the pandemic. CASE REPORT: An 8-year-old and a 16-year-old female patient were admitted with fever, vomiting, headache. Both had fulfilled the criteria and were diagnosed with MIS-C. However, they both had remarkable persistent costovertebral angle tenderness, which was unexpected in MIS-C. In Case-1, urine analysis showed microscopic hematuria without pyuria, and urine culture showed no bacterial growth. Case-2 had microscopic hematuria and pyuria with Escherichia coli growth in urine culture. Contrast-enhanced computed tomography showed wedge-shaped hypodense multiple lesions in bilateral kidneys for Case-1, in the right kidney for Case-2. They diagnosed acute focal bacterial nephritis (AFBN). CONCLUSIONS: The diagnostic criteria of MIS-C can overlap with the symptoms of other severe septic infections such as AFBN, which is a rare urinary tract infection, diagnosed by imaging of localized renal inflammatory mass-like or wedge-shaped lesion. A detailed anamnesis and careful physical examination may help differential diagnosis.