Background: Multisystem Inflammatory Syndrome in Children (MIS-C) is a severe, post-infectious hyperinflammatory complication of SARS-CoV-۲. International guidelines recommend intravenous immunoglobulin (IVIG) combined with corticosteroids as first-line therapy. However, IVIG is costly and often in short supply, particularly in resource-limited settings. This study describes the clinical findings, treatment patterns, and outcomes of MIS-C patients from a large tertiary center in Iran, with a focus on evaluating outcomes for patients treated with corticosteroid monotherapy. Methods: This retrospective, observational study analyzed medical records of children diagnosed with Multisystem Inflammatory Syndrome in Children (MIS-C) at Akbar Children's Hospital, Mashhad, Iran, from ۲۰۲۰ to ۲۰۲۱. Out of ۱۷۹ discharged patients, ۸۴ met the CDC case definition for MIS-C. Participants received either intravenous immunoglobulin (IVIG) with or without corticosteroids (۶۲ patients) or corticosteroids alone (۲۱ patients). Statistical analyses included the Mann-Whitney U test and Fisher's Exact Test, with significance set at p ۰.۰۵. Results: Over ۲۱ months, ۱۷۹ children were discharged with final diagnosis of MIS-C. Upon re-examination, ۸۴ patients (۴۶.۹%) matched CDC criteria. Based on the immunomodulatory therapy administered, the study population consisted of ۶۲ patients who received IVIG with or without corticosteroids and ۲۱ who received corticosteroids alone. The cohort revealed two distinct phenotypes. The IVIG group exhibited a cardiodominant presentation (۸۷.۱% cardiac involvement), while the steroid-alone group was younger, had more comorbidities (۳۸.۱% vs. ۶.۵%, p۰.۰۰۱), and presented with prominent gastrointestinal, respiratory (۳۸.۱%), and neurologic (۳۸.۱%) symptoms. Mortality was comparable between groups (۸.۱% vs. ۹.۵%, p=۱.۰۰۰). Strikingly, no patient in the steroid-alone group had residual cardiac abnormalities at follow-up versus ۳۵.۵% in the IVIG group (p=۰.۰۰۱). The overall clinical profile showed high rates of gastrointestinal (۹۸.۸%) and cardiac (۷۵.۹%) involvement. Conclusion: In this cohort, corticosteroid monotherapy was associated with favorable outcomes in MIS-C patients without severe initial cardiac involvement. The findings support the feasibility of phenotype-directed, resource-aware treatment strategies in settings with limited access to IVIG.
