Case Report/Case SeriesGranulocytic Sarcoma Mimicking HSV EncephalitisShah, Reena S. MD*; Shin, Robert K. MD*; Castellani, Rudy J. MD†Author Information From the Departments of *Neurology, and †Pathology, University of Maryland, Baltimore, MD. Reprints: Robert K. Shin, MD, Department of Neurology, University of Maryland, 110 S. Paca St, Baltimore, MD 21201. E-mail: [email protected]. The Neurologist: September 2010 - Volume 16 - Issue 5 - p 319-321 doi: 10.1097/NRL.0b013e3181b0be8d Buy Metrics Abstract Introduction: Granulocytic sarcomas, or chloromas, are extramedullary collections of immature granulocytes. Central nervous system involvement is rare and of those cases described, most are complications of acute myelogenous leukemia. Case Report: A 40-year-old man with chronic myelogenous leukemia presented with seizure and encephalopathy. Magnetic resonance imaging of the brain revealed temporal T2 hyperintensities with gyriform cortical enhancement. Cerebrospinal fluid showed mild pleocytosis and elevated protein. Electroencephalography demonstrated periodic lateralized epileptiform discharges. Acyclovir was initiated for herpes simplex encephalitis, however, follow-up MRI showed extension of the lesion. MR spectroscopy suggested tumor, confirmed by brain biopsy. Postradiation MRI showed a significant decrease in lesion size. Conclusion: Granulocytic sarcoma can present as intraparenchymal cerebral lesions in patients with chronic myelogenous leukemia and may mimic herpes simplex encephalitis. © 2010 Lippincott Williams & Wilkins, Inc.