CD4 and thymic carcinoma: Predictably, thymomas show a higher proportion of lymphocytic infiltrate compared to thymic carcinomas; AB, B1, and B2 thymomas show a higher proportion of CD4+/CD8+ immature cells, while B3 thymomas and thymic carcinomas show numerous terminally differentiated CD4+ or CD8+ cells, mostly polarized toward a CD8+ cytotoxic phenotype [93].