CD19 and neoplasm: From the perspective of tumor immune infiltration, we have a novel viewpoint in group 3-MBs: group 3-MBs have a grim outcome result from multiple adverse prognostic factors, such as MYC amplification, presence of metastases, and large cell/anaplastic histology (13), while our study indicates the higher presence of endothelial cells and infiltrating immune cells (CD19, CD8, and Treg) in tumor bulk of group 3-MBs compared with the other subgroups.