NFKB1 and aneurysmal bone cyst: The ABC subtype is characterised by a constitutively activated nuclear factor‐κB (NF‐κB) pathway, which promotes tumor proliferation/survival and confers chemotherapy resistance.43, 44 The constitutive activation of NF‐κB is also required for IL‐34 expression in the doxorubicin‐resistant A549 lung cancer cells.17 Thus, the higher percentage of IL‐34+ cases in the ABC subtype might be explained at least in part by the NF‐κB activation.