Unlike other DLBCL subtypes, the malignant transformation of ABC DLBCL frequently involves aberrant B cell receptor (BCR) activation through concurrent or independent mutations of the two signaling subunits of BCR, CD79A/B (24% of cases), or downstream molecules, CARD11 (10%) and MYD88 (35%), providing tumor cells with a constitutive activation of these survival and proliferation pathways [6,7,8,9]. Here, CARD11 is linked to aneurysmal bone cyst.