We report orthotopic (life‐supporting) survival of genetically engineered porcine cardiac xenografts (with six gene modifications) for almost 9 months in baboon recipients. This work builds on our previously reported heterotopic cardiac xenograft (three gene modifications) survival up to 945 days with an anti‐CD40 monoclonal antibody‐based immunosuppression. In this current study, life‐supporting xenografts containing multiple human complement regulatory, thromboregulatory, and anti‐inflammatory proteins, in addition to growth hormone receptor knockout (KO) and carbohydrate antigen KOs, were transplanted in the baboons. Selective “multi‐gene” xenografts demonstrate survival greater than 8 months without the requirement of adjunctive medications and without evidence of abnormal xenograft thickness or rejection. These data demonstrate that selective “multi‐gene” modifications improve cardiac xenograft survival significantly and may be foundational for paving the way to bridge transplantation in humans.

Myelodysplastic/myeloproliferative neoplasm (MPN), unclassifiable (MDS/MPN-U), has clinical and morphologic features of both myelodysplastic syndrome (MDS) and myeloproliferative neoplasms (MPNs), and does not meet diagnostic criteria for any other specific entity within MDS, MPN, or MPN, including therapy-related myeloid neoplasms, and cases evolving from a prior MDS or MPN. Diagnostic criteria for MDS/MPN-U include, among other specifications, a platelet count of greater than or equal to 450 × 10E9/L associated with bone marrow megakaryocytic proliferation. We present the case of a young adult patient with a several-year reported history of cytopenias, found to have thrombocytosis and 5% circulating blasts. Surprisingly, his bone marrow biopsy demonstrated hypocellularity (10%), with 5% to 10% blasts, myeloid hypoplasia, minimal fibrosis, and focal megakaryocytic dyspoiesis but no hyperplasia. The constellation of morphologic and clinical features presents a challenging differential diagnosis between MDS/MPN-U and MDS with excess blasts (as well as thrombocytosis). Molecular testing interestingly demonstrated an SF3B1 mutation, although no increased ring sideroblasts were found by iron staining. Cases such as these may prove instructive in refining our understanding of the MDS/MPN category, as well as its relationship to myelodysplasia and the complex molecular genetic landscape underlying myeloid neoplasia.

A 13-year-old male presented to the pediatric otolaryngology clinic with a 2-year history of a right neck mass that had slowly increased in size. He denied any associated symptoms of pain, fevers, chills, malaise, night sweats, unintentional weight loss, prior history of neck masses, recent upper respiratory tract infections, or skin lesions. He was the product of a full-term pregnancy with up-to-date immunizations. Physical examination revealed a 2.5-cm firm, ovoid, mobile, and nontender mass at the apex of the posterior triangle of the right neck without any associated overlying skin changes. The remainder of the head and neck examination was unremarkable. Doppler ultrasonography revealed a 1.9 × 1.8 × 0.9-cm hypoechoic mass, and subsequent fine-needle aspirates demonstrated cells with elongated nuclei and eccentric blue cytoplasm in a background of myxoid stroma. The mass was excised in entirety without issue. At the time of surgery, the deep surface of the mass was found to be adherent to the sternocleidomastoid muscle. The lesion was resected with a cuff of muscle and sent for permanent histopathological examination. This revealed proliferation of bland spindle cells with plump nuclei and eosinophilic cytoplasm arranged as loose fascicles in a background of myxoid stroma (Figure 1). These cells were positive for mucin 4 (MUC4), epithelial membrane antigen (EMA), and transducing-like enhancer of split 1 (TLE1) immunohistochemical stains. Fluorescence in situ hybridization (FISH) revealed a positive FUS (16p11) gene rearrangement.