LAUSR

Polycythemia vera (PV) is a hematopoietic stem cell disorder characterized by janus kinase 2 (JAK2) mutations and an increased cardiovascular risk. Low-risk PV patients (those younger than 60 years of age and without thrombosis history) are managed with phlebotomies and low-dose aspirin, whereas high-risk patients usually receive hydroxyurea or interferons. However, despite the phlebotomies and thromboprophylaxis, low-risk PV patients still have a residual annual rate of thrombosis of ~ 2% [1]. Recent reports have suggested that autoimmune disorders (AD) can be found in a substantial proportion of PV patients and may even be associated with the development of myeloproliferative neoplasms [2]. Moreover, PV patients with AD may be more susceptible to thrombosis than those without AD [3]. Multiple sclerosis (MS) is a debilitating demyelinating AD of the brain and the spinal cord that carries intrinsically high cardiovascular risk [4]. Here, we present a patient with concomitant PV and MS who we successfully treated with glatiramer acetate, an immunomodulatory drug frequently used to treat MS. A 43-year-old Caucasian female presented in July 2020 with visual disturbances, periodic left-arm weaknesses, and paresthesias. Blood counts at diagnosis were leukocytes 11.9 × 109//L, hemoglobin 161 g/L, hematocrit 49.2%, and platelets 456 × 109//L. She was a tobacco smoker with unremarkable prior medical history; however, blood tests performed 2 years earlier revealed she had mild leukocytosis (11.6 × 109//L) and thrombocytosis (557 × 109//L), suggesting a possibility of an underlying hematological disorder. At the current admission, she was mildly plethoric without hepatosplenomegaly. Magnetic resonance (MR) revealed multiple demyelinating lesions of the brain (Fig. 1a), and oligoclonal bands were present in the spinal fluid. The JAK2-V617F mutation was positive, serum erythropoietin was subnormal (2 IU/L; reference range 4–29), and the bone marrow was consistent with PV. She received highdose methylprednisolone (500 mg for 5 days) and was then started on glatiramer acetate (40 mg subcutaneously thriceweekly), low-dose aspirin, and phlebotomies (a total of five procedures were performed in the following 2 months). She was also advised to quit smoking. With these treatments, the neurological deficit promptly resolved. During the 18-month follow-up, her leukocyte and platelet counts gradually normalized, and the need for phlebotomies had diminished (Fig. 1b). Unfortunately, JAK2 allele burden was unavailable at diagnosis, but at 16-month follow-up measured 20.6%, suggesting a potentially lower risk of future venous thrombosis [5]. More importantly, the patient was continuously asymptomatic with stationary demyelinating lesions on brain MR. Even though the aberrant activation of the JAK-STAT signaling pathway has been implicated in the pathogenesis of MS [6], this neuroinflammatory disorder has been extremely rarely reported in PV [7]. For this reason, the presented clinical scenario raised major uncertainties * Ivan Krečak [email protected]