Fostamatinib Dual Immunomodulation in Post-Haploidentical HSCT Autoimmune Cytopenia and Autoimmune Hepatitis: A Case Report and Review of Literature

To describe the effectiveness and safety of fostamatinib off-label use in a pediatric patient with autoimmune cytopenia and autoimmune hepatitis following allogeneic hematopoietic stem cell transplantation (HSCT). We report the detailed changes in clinical, histopathological, and cytokine profiling in a pediatric HSCT recipient during treatment with fostamatinib. Fostamatinib administration was well-tolerated with no adverse events observed, leading to sustained hematological recovery and a significant improvement in liver enzyme levels. Histological features confirmed the complete remission of autoimmune hepatitis. Cytokine profiling demonstrated substantial normalization of pro-inflammatory markers, downregulated at onset. Fostamatinib demonstrated a dual benefit in resolving autoimmune cytopenia and immune-mediated liver inflammation, supporting its potential as a therapeutic option for immune dysregulation following allogeneic HSCT.