Thymic epithelial tumors (TETs) sit at a unique intersection of cancer, central tolerance, and autoimmunity. These tumors arise in the thymus, an immune-rich organ responsible for T-cell education, and despite their low tumor mutational burden (TMB) and microsatellite stability, they display paradoxical behavior under immune checkpoint inhibition. This review synthesizes data on thymic biology, paraneoplastic autoimmunity, molecular profiling, and clinical trials of immune checkpoint inhibitors