Obstructive Sleep Apnea Does Not Exclude Polycythemia Vera: A Case Report

Introduction: Polycythemia vera (PV) is one of the myeloproliferative neoplasms (MPN) diagnosed by World Health Organization (WHO) criteria 2016, which requires the presence of 3 major criteria: high hemoglobin/hematocrit, bone marrow findings, and Janus Kinase 2 (JAK2) mutation or two major and one minor criteria, including erythropoietin (EPO) level. 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 (CPAP) machine, 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 JAK2 and EPO testing to avoid missing PV.