Isolated cerebellar infarction in a case of JAK 2 mutation-negative polycythemia vera: A case report

Polycythemia vera is a myeloproliferative disorder caused by clonal expansion of erythroid precursors in the bone marrow commonly due to a mutation in the Janus kinase 2 (JAK2) gene located in the short arm of chromosome 9. Hyperviscosity of blood due to high hematocrit causes a low flow state that may predispose to infarct. These commonly occur in the supratentorial compartment. The case of a 46-year-old man who had an isolated cerebellar infarct with high hematocrit and hemoglobin levels and low serum erythropoietin levels is described. Further investigations eventually led to the unmasking of a JAK2 mutation-negative polycythemia vera.