KITLG and thymoma: A previous study reported that KITLG as a critical mast cell growth factor, secreted by Th17 cell‐mediated keratinocytes, could stimulate the accumulation and proliferation of mast cells, and mast cells could act as antigen‐presenting cells or effector cells secreting various immune responses to promote immune disorders.34 Combined with our latest research (unpublished data), we found that the balance of Th17/Treg was abnormal and the antigen presentation ability of dendritic cells improved in the thymoma microenvironment, which impacted the positive and negative selection of T cells.