CTLA4 and extramammary Paget disease: Skin cancers, the most prevalent human malignancies, primarily include melanoma (MM), basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (cSCC), and extramammary Paget disease (EMPD).[1, 2, 3] While surgical resection remains the standard for localized disease, immune checkpoint inhibitors targeting PD‐1 and CTLA‐4 have demonstrated significant efficacy in advanced or metastatic BCC, cSCC, and MM.[2, 4, 5, 6] Despite subtype heterogeneity, these malignancies exhibit shared tumor microenvironment (TME) mechanisms driving immune suppression and evasion.