PIM1 mutations were frequent in adult HGBCL, NOS (20%, 9/45 HGBCL, NOS) and comparable with DLBCL subtypes (i.e., 24% in ABC‐DLBCL [9/37] and 15% in GCB‐DLBCL [7/48]), but were not observed in adult mBL. This evidence concerns the gene PIM1 and aneurysmal bone cyst.