CCL21 and neoplasm: Importantly, we found that the detected immune cell region resembles a tertiary lymphoid structure (TLS)60,61 with multiple features of TLS: the region is located near the tumor; the region primarily contains T cells and B cells, all of which are key cell types in TLS60,62–64; the region is enriched with chemokine signature genes such as CCL19 and CCL21 and T follicular helper cell signature genes such as CXCL13 and TIGIT (Fig. 5f), all of which are marker genes associated with TLS neogenesis in breast cancer60.