Idiopathic multicentric Castleman disease with TAFRO clinical subtype responsive to IL‐6/JAK inhibition: A pediatric case series

TAFRO (thrombocytopenia, anasarca, fever/elevated C‐reactive protein, reticulin myelofibrosis, renal dysfunction, and organomegaly) clinical subtype of idiopathic multicentric Castleman disease (iMCD‐TAFRO) is a rare lymphoproliferative disease characterized by systemic inflammation. First‐line treatment for iMCD‐TAFRO includes steroids and interleukin (IL)‐6 blockade. Many patients have refractory disease, which is associated with significant morbidity and mortality, and treatment remains challenging. We present two pediatric cases of iMCD‐TAFRO. One patient responded to IL‐6 blockade; the other was refractory to siltuximab and chemotherapy, ultimately responding to JAK inhibition with ruxolitinib. This is the first reported pediatric case of refractory iMCD‐TAFRO responding to JAK inhibition.