Rare disease mimicking multisystem inflammatory syndrome in children.

Multisystem inflammatory syndrome (MIS-C) is a rare but serious condition associated with SARS-CoV-2, the virus that causes COVID-19. We report a 16-year-old female who presented with seven days of fever, abdominal pain, headache, and fatigue. Physical examination revealed meningeal irritation. Laboratory findings showed pancytopenia, elevated inflammatory markers, and positive SARS-CoV-2 IgG with negative PCR. The patient had no history of COVID-19 vaccination or previous confirmed infection. Initially evaluated as MIS-C due to fever, multisystem involvement, and antibody positivity, she was subsequently diagnosed with visceral leishmaniasis after bone marrow aspiration revealed Leishmania amastigotes. This case highlights the diagnostic overlap between MIS-C and endemic infections such as leishmaniasis and underlines the importance of considering infectious etiologies in hyperinflammatory presentations, especially in endemic areas.