A 16-year-old girl with B-lineage acute lymphoblastic leukemia was hospitalized for management of fever and neutropenia. She was empirically treated with intravenous vancomycin and ceftazidime. Her fever persisted, and on the seventh day of hospitalization, she developed a painful generalized erythematous rash. There was no history of trauma, infectious contacts, travel, gardening or pet exposures.