CD4 and pachyonychia congenita: Studies have shown that immune cells with antitumor effects, such as CD4+, CD8+ effector T lymphocytes, and NK cells, are reduced or functionally inactive in PC, while immune cells with immunosuppressive effects, like tumor‐associated macrophages, Tregs, and myeloid‐derived suppressor cells, are functionally active and proliferating, thus creating a microenvironment favorable for PC immune escape [65].