BTK and B-cell chronic lymphocytic leukemia: In this case, strong evidence of clonal relationship between the 2021 and 2023 bone marrow specimens supports the latter: 1) The lymphoma cells showed a persistent CLL immunophenotype and LEF1 positivity (Figure 1) in both samples; 2) Cytogenetic studies showed overlapping abnormalities such as add(10)(q26), del(13), ‐15, ‐17, and add(18)(q23) by karyotype and D13S319 and TP53 loss by FISH (Table 1); 3) NGS detected identical mutations in BTK, RPS15, and TP53.