Next, to reveal when L1196M ALK mutation emerged in lymphoma cells over time, ddPCR analysis using an L1196M ALK mutation detection probe set (LBx Probe ALK L1196M (A071); Riken Genesis, Tokyo, Japan) was performed for each of the blood cell samples preserved over time and the pulmonary lymphoma sample at the second relapse (Figure 1). The gene discussed is ALK; the disease is lymphoma.