Abbreviations
LCH Langerhans cell histiocytosis
MAPK Mitogen-activated protein kinase
sCD25 Soluble CD25
IL-2Rα α-subunit of interleukin-2 receptor
SS Single-system
MS Multi-system
RO Risk organ
ELISA Enzyme-linked immunosorbent assay
IFN-γ Interferon-γ
TNF-α Tumor necrosis factor α
cf Cell-free
ddPCR Droplet Digital PCR
ROC Receiver operating characteristic
PPV Positive predictive value
NPV Negative predictive value
PFS Progression-free survival
SPSS Statistical Package for Social Sciences
CNS Central nervous system
MAS-HLH Macrophage activation syndrome-Hemophagocytic lymphohistiocytosis
AUC Area under the curve