Extramedullary tumor of monoblasts in the central nervous system: presenting feature of simultaneous bone marrow involvement by acute monocytic leukemia.

An extramedullary tumor of monoblasts in the central nervous system has been described in the literature as a single case report, preceding the development of acute monocytic leukemia by 1 year. We report a previously undescribed presentation of acute monocytic leukemia as a left temporal lobe extra-axial mass with concomitant bone marrow involvement. We describe our findings in order to heighten awareness of this entity, which may be encountered in morphologic evaluation of central nervous system masses.