Autoimmune and Inflammatory Diseases in Polycythemia Vera and Essential Thrombocythemia: Impact on Disease Outcomes and Comorbidities

To the Editor, Polycythemia vera (PV) and essential thrombocythemia (ET) are chronic Philadelphia chromosome negative myeloprolifer- ative neoplasms (MPN) characterized by clonal hematopoiesis, thrombotic risk, and variable disease evolution [1, 2]. Increasing evidence supports a role for immune dysregulation and inflam- matory pathways in disease development and clinical heteroge- neity, although their clinical implications remain incompletely defined [3]. Epidemiological studies have reported an association between prior autoimmune diseases and an increased risk of develop- ing MPN [4]. Autoimmune or inflammatory diseases (AID) have also been described in approximately 6%–8% of patients with MPN, with heterogeneous effects on clinical features and survival across cohorts [5, 6]. However, the clinical burden of AID in patients specifically affected by PV and ET, particularly concerning disease outcomes and comorbidity profiles, remains poorly defined. We therefore evaluated the prevalence of AID in a large cohort of patients with PV and ET and assessed their association with disease outcomes and comorbidities. A history of AID was associated with an increased risk of SC in unadjusted analyses, particularly after exclusion of NMSC, although this association was attenuated after multivariable adjustment. This finding suggests that part of the observed risk may be explained by coexisting clinical factors, including prior malignancy history and cardiometabolic comorbidities, while remaining consistent with prior observations linking chronic immune dysregulation with carcinogenesis across multiple disease settings [5, 10–12]. A particularly relevant observation was the significantly increased risk of incident AID after MPN diagnosis among patients with prior AID, in- dependent of sex, age, and hypertension