Diagnosis marker for rare hematopoietic tumor, test method, therapeutic agent, and screening method

Diagnosis markers that can provide novel diagnosis criteria for blastic plasmacytoid dendritic cell neoplasm (BPDCN) are searched, and the presence of an immunoblastoid-like cell form, the reconstruction of 8q24 and the expression of MYC are established as novel markers for subtyping BPDCN. In addition, it is found that a BET bromo domain-selective inhibitor, an inhibitor capable of directly or indirectly inhibiting the expression or function of MYC or the signaling pathway of MYC such as an aurora kinase inhibitor, an HDAC inhibitor or a BCL2 family protein inhibitor is effective as a therapeutic agent for a MYC-expressing group.