Fig. 1: Clonal divergence and distinct mutational profiles of extramedullary AML compared to paired bone marrow disease.

A Comparative mutation frequency analysis of eAML and concurrent bone marrow samples. Bar plot illustrating the frequency of gene mutations in extramedullary AML samples (eAML, blue) compared to paired, concomitant bone marrow samples (BMc, orange), FLT3 mutations are enriched in eAML cases compared to paired BM samples (Fisher's exact p = 0.0032). B FLT3 mutation frequency and distribution between eAML and bone marrow samples. Stacked bar chart comparing the number and types of FLT3 mutations between eAML and BM (all samples). FLT3 mutations, including internal tandem duplications (ITD) and tyrosine kinase domain (TKD) mutations, were more prevalent at relapse and significantly enriched in eAML sites compared to BM samples (Fisher's exact p = 0.0064). C Site-specific clonal evolutionary trajectories. Categorization of the 20 paired eAML and BM samples, showing: concordant mutational status (n = 7): cases in which BM and eAML shared highly similar mutational profiles, suggesting a common clonal origin with minimal divergence. Nearly all exhibited equivalent variant allele frequencies (nVAFs) for key mutations in both compartments, indicating parallel evolution of dominant clones (Patient IDs: 6, 12, 15, 19, 28, 29). One case (Patient ID: 7) showed differences in nVAFs between BM and eAML. Discordant mutational status (n = 14): cases in which BM and eAML displayed distinct mutational landscapes, suggesting independent clonal evolution. These are further classified as:• Concomitant BM involvement (n = 7; Patient IDs: 2, 9, 10, 13, 17, 21, 22): leukemia was detected in both BM and extramedullary sites. • Isolated eAML (n = 6; Patient IDs: 1, 4, 8, 18, 24, 27): the paired BM lacked morphologic evidence of leukemia but harbored genetic alterations. D–J Fish plots illustrating distinct patterns of clonal evolution in eAML versus BM sites. Mutations are color-coded according to the legend. D–F show cases of concomitant BM and eAML with discordant mutational profiles. These cases indicate divergent evolutionary trajectories and potential site-specific selective pressures driving leukemic progression. G illustrates an isolated myeloid sarcoma relapse with no detectable BM involvement at relapse, demonstrating spatially restricted clonal evolution. H-I Represent cases of concordant mutational profiles in BM and eAML, with similar clonal expansion patterns (H), or different clonal expansion (I). J presents progressive eAML lesions containing subclones derived from both BM and the initial eAML site at diagnosis, highlighting intercompartmental clonal exchange.