Isolated extramedullary relapse of chronic myelogenous leukemia (CML) after allogeneic stem cell transplant is rare. There is a case report of a child who developed a granulocytic sarcoma of the maxillary and sphenoid sinuses and lumbosacral spinal cord mass 18 months after allogeneic bone marrow transplant for CML. He was presented with per orbital edema and neurological deficit of lower extremities and a mass lesion was found on spinal cord imaging. No evidence of hematologic relapse was identified at that time by bone marrow histology or cytogenetic. The patient died 1 month later with a picture of pneumonia, left ventricular dysfunction and a cardiopulmonary arrest on a presumed underlying sepsis with infectious etiology. Granulocytic sarcoma should be considered in the differential diagnosis of mass lesions presenting after allogeneic bone marrow transplantation for CML, even if there is no evidence of bone marrow involvement.