Myeloid sarcoma of the septum pellucidum causing hallucinations and personality changes in an elderly woman: a case report.

Myeloid sarcoma is an extramedullary tumor composed of myeloid blasts, most commonly involving the skin, lymph nodes, and soft tissues. We report a rare case of myeloid sarcoma of the central nervous system (CNS) causing neuropsychiatric symptoms in an elderly woman with a history of JAK2-positive polycythemia vera and acute myeloid leukemia (AML) in long-term remission. The patient presented with a one-month history of complex visual hallucinations, short-term memory loss, and personality changes. Magnetic resonance imaging revealed a 2.4-cm enhancing mass in the septum pellucidum extending between the frontal horns of the lateral ventricle. Cytological analysis of the cerebrospinal fluid showed pleocytosis, and flow cytometry identified a 50% population of CD34 + blasts, consistent with the immunophenotype of the patient's prior biopsy-proven AML. This case highlights an exceedingly unusual presentation of AML relapse and emphasizes the need for clinicians to consider CNS involvement in hematologic patients presenting with new-onset neuropsychiatric symptoms, regardless of remission status.