The TIL-rich DCIS in our cohort contained a high fraction (almost 60%) of high-grade DCIS and was richer in all investigated TIL phenotypes (CD8+, CD4+, FoxP3+, CD20+ and CD38+) than the TIL-poor DCIS subcategory, which contained much less high-grade lesions. This evidence concerns the gene CD4 and ductal breast carcinoma in situ.