Polycythemia Vera with Incidental Large Aortic Aneurysm and Giant Cell Arteritis: Case Report.

Polycythemia vera (PV) is a JAK2-mutated myeloproliferative neoplasm associated with thrombotic and vascular complications. Giant cell arteritis (GCA) is a granulomatous large-vessel vasculitis that may involve the aorta and can present as aortitis or aneurysm formation. Coexistence of PV and GCA is uncommon and may complicate diagnosis and management. We report a 41-year-old man with low-risk PV (JAK2 V617F-positive) who presented 4 months later with an ischemic stroke and was incidentally found to have a 5.0 cm ascending aortic aneurysm. Despite cytoreduction and surveillance, the aneurysm enlarged to 5.6 cm and was repaired electively. Histopathology of the resected aortic wall showed granulomatous inflammation with multinucleated giant cells and elastic lamina fragmentation, consistent with GCA. The patient had no cranial or systemic features suggestive of active GCA at diagnosis; therefore, systemic corticosteroids were deferred and close rheumatology follow-up was arranged. This case underscores the need to consider inflammatory aortitis/large-vessel vasculitis when atypical vascular findings occur in PV and highlights the value of multidisciplinary evaluation.