Analysis of a patient-derived xenograft from a KRAS^G12S-mutant patient with ECD. (A) Fludeoxyglucose positron emission tomography (FDG-PET) imaging and histologic and immunohistochemical analysis of the KRAS^G12S-mutant ECD patient’s heart biopsy specimen (scale bars represent 200 µm). (B) Flow cytometric analysis of BM, spleen, liver, and lung of recipient NSGS mouse 90 days postxenotransplantation with CD34⁺ cells from the same KRAS^G12S-mutant ECD patient. (C) Histologic and immunohistochemical analysis of engrafted tissue from the recipient mouse (scale bars represent 200 µm). (D) Sanger sequencing of genomic DNA from hCD45⁺ cells purified from recipient mouse BM (left) and spleen (right) revealing a KRAS^G12S mutation in engrafted human hematopoietic cells. H&E, hematoxylin and eosin.