Choreiform Movements and Pachymeningeal Enhancement in an Elderly Patient With Abnormal Blood Counts: A Case Report and Review of Literature.

Polycythemia vera (PV) is a clonal myeloproliferative neoplasm primarily caused by the JAK2V617F mutation, present in 95% of patients. It results in erythropoietin-independent hematopoietic proliferation, erythrocytosis, increased hematocrit (Hct), leukocytosis, thrombocytosis, and hyperviscosity, predisposing patients to thrombotic events and neurologic deficits, including erythromelalgia and pruritus. Neurologic manifestations can occur, such as transient ischemic attack (TIA) and stroke. We report an 83-year-old woman, PV patient who presented with chorea and magnetic resonance imaging (MRI) of her brain showed pachymeningeal enhancement (dural-arachnoid enhancement); this radiological finding is most commonly described in intracranial hypotension, autoimmune conditions, infection, and neoplastic processes and has not been reported in PV. Laboratory findings included complete blood count (CBC) showed severe erythrocytosis, moderate leukocytosis with moderate, mild thrombocytosis; bone marrow (BM) aspiration and biopsy showed hypercellular BM and marked megakaryocytic hyperplasia; and positive JAK2V617F mutation with 80% JAK2 DNA, suggestive of PV as the underlying cause. The patient underwent phlebotomy and was started on Aspirin. Following treatment, she showed dramatic improvement in choreiform movements. Hydroxyurea 500 mg three times daily was subsequently added, leading to complete hematologic response and resolution of pachymeningeal thickening on follow up MRI. This case suggested association between polycythemia vera and choreiform movements and a possible mechanism is proposed.