Supplementary Material for: Obstructive sleep apnea does not mandate secondary polycythemia and does not exclude Polycythemia Vera; case report

Introduction: Polycythemia Vera (PV) is one of the myeloproliferative neoplasm (MPN) diagnosed by World Health Organization (WHO) criteria 2016, which requires presence of 3 major criteria; high Hemoglobin/Hematocrit, Bone Marrow findings, and Janus Kinase 2 mutation (JAK 2) or two major and one minor criteria, including erythropoietin level (EPO) . However, in clinical practice, difficulties in diagnosis can arise as it may be masked by secondary causes for erythrocytosis such as smoking or obstructive sleep apnea (OSA). Case presentation: Here, we report a 55-year old gentleman, morbidly obese with OSA on home Continuous Positive Airway Pressure machine (CPAP), who was incidentally found to have polycythemia. Further evaluation confirmed the diagnosis of PV. Conclusion: PV can be masked by the assumption of secondary polycythemia based on history. This underscores the importance of screening such cohort through JAK 2 and EPO testing to avoid missing PV.