Background Patients with myeloproliferative neoplasms (MPNs), such as polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), are at an increased risk of recurrent thromboembolic events (TEs) and hemorrhagic complications. Anticoagulation with vitamin K antagonists (VKAs) had been the standard of care until the recent US Food and Drug Administration approval of direct oral anticoagulants (DOACs) for treatment of cancer-associated thrombosis. However, since patients with MPNs were underrepresented in large studies, the use of DOACs in patients with MPN-associated thrombosis remains understudied. Objectives The primary objective of this study was to establish the incidence of recurrent TEs and hemorrhagic complications in patients with MPN-associated thrombosis treated with DOACs versus VKAs as first-line therapy. Methods Data from 30 patients ≥18 years old with established diagnoses of PV or ET who were treated with either DOACs or VKAs as the first-line anticoagulant for arterial and/or venous thrombosis were reviewed to determine the incidence of recurrent TEs as well as hemorrhagic complications. Results Nineteen patients were treated with DOACs, and 11 were treated with VKAs. Of those on DOACs, 1 had a recurrent thrombosis, and 4 had bleeding events. Of the 11 patients treated with VKAs, 1 had a recurrent thrombotic event, and 1 had a bleeding event. Conclusion Our data did not demonstrate a significant difference in recurrent TEs or bleeding events in patients with MPN-associated thrombosis anticoagulated with either DOACs or VKAs.

Neutrophil Extracellular Traps (NETs) are large neutrophil-derived structures composed of decondensed chromatin, cytosolic, and granule proteins. NETs play an important role in fighting infection, inflammation, thrombosis, and tumor progression processes, yet their fast and reliable identification has been challenging. Smudge cells (SCs) are a subcategory of white cells identified by CellaVision^®, a hematology autoanalyzer routinely used in clinical practice that uses digital imaging to generate “manual” differentials of peripheral blood smears. We hypothesize that a proportion of cells identified in the SC category by CellaVision^® Hematology Autoanalyzers are actually NETs. We demonstrate that NET-like SCs are not present in normal blood samples, nor are they an artifact of smear preparation. NET-like SCs stain positive for neutrophil markers such as myeloperoxidase, leukocyte alkaline phosphatase, and neutrophil elastase. On flow cytometry, cells from samples with high percent NET-like SCs that are positive for surface DNA are also positive for CD45, myeloperoxidase and markers of neutrophil activation and CD66b. Samples with NET-like SCs have a strong side fluorescent (SFL) signal on the white count and nucleated red cells (WNR) scattergram, representing cells with high nucleic acid content. When compared to patients with low percent SCs, those with a high percentage of SCs have a significantly higher incidence of documented bacterial and viral infections. The current methodology of NET identification is time-consuming, complicated, and cumbersome. In this study, we present data supporting identification of NETs by CellaVision^®, allowing for easy, fast, cost-effective, and high throughput identification of NETs that is available in real time and may serve as a positive marker for a bacterial or viral infections.