Interestingly, H&E and IHC staining demonstrated an immune infiltrate positive for CD4+, CD8+ T-cells, and CD20+ B-cells, as well as positivity for CXCL13 and CD21, which were consistent with TLS and not present on pre-treatment biopsies (Fig. 4b, 4d). Here, CXCL13 is linked to Tumor Lysis Syndrome.