Myeloid sarcoma (MS), previously known as granulocytic sarcoma, is a rare, localized, tumor mass composed of myeloid precursor cells, with or without maturation, and occurring at an anatomical site other than the bone marrow (BM). Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), in contrast, is a B-cell hematological malignancy. We describe the first reported case of concurrent presentation of nodal MS and of BM CLL/SLL in the same patient. Fatal leukemic central nervous system infiltration was the final outcome. We provide possible explanations and investigate the pathophysiology of this unique, previously unreported co-morbidity.