Cutaneous squamous cell carcinoma (cSCC) is the most common malignancy in immunesuppressed organ transplant recipients (OTRs). Whilst rates of other malignancies (both cutaneous and non-cutaneous) are elevated in this population, the increase is far less striking. This suggests that cSCC must be a highly immunogenic tumor. The tumor immune microenvironment is altered in cSCC from OTRs. It has reduced anti-tumor properties and instead provides an environment that facilitates tumor growth and survival. Understanding the composition and function of the tumor immune microenvironment in cSCC from OTRs is useful for prognostication and therapeutic decisions.

The immune system plays a key role in the suppression and progression of basal cell carcinoma (BCC). The primary aetiological factor for BCC development is exposure to ultraviolet radiation (UVR) which, particularly in lighter Fitzpatrick skin types, leads to the accumulation of DNA damage. UVR has roles in the generation of an immunosuppressive environment, facilitating cancer progression. Rates of BCC are elevated in immunosuppressed patients, and BCC may undergo spontaneous immune-mediated regression. Histologic and immunohistochemical profiling of BCCs consistently demonstrates the presence of an immune infiltrate and associated immune proteins. Early studies of immune checkpoint inhibitors reveal promising results in BCC. Therefore, the host immune system and tumor responses to it are important in BCC pathogenesis. Understanding these interactions will be beneficial for disease prognostication and therapeutic decisions.