Recent progress in next-generation sequencing technologies has shown that tumor cells in many solid cancers undergo dynamic clonal evolution. 1 Notably, diverse clones have been observed in biopsy samples acquired from primary or metastatic legions in solid cancers. 2-4 In contrast, intratumor heterogeneity (ITH) in lymphomas is less characterized: samples are taken only for diagnosis and multiregional sample collection is rarely performed in living patients, because chemotherapy rather than surgery is the standard treatment for most lymphoma subtypes. Black dots indicate a tumor mass; organs with red diagonal lines represent intravascular tumor invasions. kid, kidney; ll, left lung; lym, lymph node; rl1, right lung; spl, spleen. ...this analysis shows a clear phylogenic tree of aggressive lymphoma, confirming that dynamic time-dependent and spatial ITH occurs even in systemic disease.