Cerebellar granulocytic sarcoma in an infant with CD56+ acute monoblastic leukemia.

Granulocytic sarcoma (GS) is a form of extramedullary leukaemia (EML). The presence of the neural cell adhesion molecule (NCAM) on the surface of the blasts, which is recognized by the CD56 monoclonal antibody, enhances their propensity for tissue penetration. GS within the central nervous system (CNS), in particular within the cerebellum, is extremely uncommon. We review the literature and describe an infant with isolated cerebellar GS relapse, which antedated a CD56+ acute monoblastic leukaemia bone marrow (BM) relapse.