Abstract
Leukemic masses are a known complication in patients with hematologic malignancies. Here we present a case regarding a patient with recently diagnosed B-acute lymphoblastic leukemia (B-ALL) who presented with multiple sites of extramedullary involvement including an anterior mediastinal mass. This mass persisted despite multiple rounds of multiagent cytotoxic therapy. In this report, we summarize the literature regarding mediastinal masses in the setting of B-ALL and illustrate that such masses in patients with leukemias may have surprising etiology, separate from the primary disease.