Intracranial granulocytic sarcoma in postpolycythemia myeloid metaplasia.

A 57-year-old man with a ten-year history of polycythemia vera had myeloid metaplasia, extramedullary hematopoiesis, and terminally, possible leukemic transformation with intracranial granulocytic sarcoma. Radiation therapy produced a partial and temporary beneficial response. Intracranial granulocytic sarcoma is typically associated with acute or chronic myelogenous leukemia and has not been previously associated with postpolycythemia myeloid metaplasia.