Study cohort and mutational landscape of extramedullary (EMD) and bone marrow aspirate (BMA) samples. (A) The study cohort included 18 extramedullary tumor samples and 20 CD138⁺-sorted BMA samples, with 6 paired EMD and BMA samples collected from the same time point from the same patient. (B) The top genes with mutations in EMD are displayed, highlighting the prevalence of MAPK pathway mutations and alterations in genes involved in the epigenetic regulation and SWI/SNF complex. (C) Mutation frequency of the top genes identified in EMD samples is depicted for the BMA samples. The proportion of mutations in de novo vs secondary samples is indicated at the bottom of panels B-C.