JAK2-negative presentations pose significant diagnostic challenges and likely harbor a spectrum of molecular drivers that remain incompletely characterized.<h4>Case presentation</h4>We report a case of JAK2-negative PV-like MPN in a 53-year-old male presenting with erythrocytosis, suppressed erythropoietin, panmyelotic bone marrow morphology, and splenic vein thrombosis. This evidence concerns the gene JAK2 and acquired polycythemia vera.