A patient with longstanding agnogenic myeloid metaplasia developed a progressive dementia. CT scanning demonstrated multiple intracranial masses, and a Fe52 bone marrow scan demonstrated erythroid activity within the masses and confirmed the suspicion of extra-medullary hematopoiesis. A potentially hazardous biopsy was avoided, and a course of cranial irradiation was administered, resulting in regression of the masses and clearing of the patient's dementia. Fe52 scintigraphy provides a specific and useful diagnostic approach which may eliminate the need for invasive procedures.