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.