Abstract
A 39-year-old man was admitted to our university hospital because of diffuse pulmonary infiltrates on chest X-ray. He had been diagnosed with T-acute lymphoblastic leukaemia/lymphoblastic lymphoma three years before and had been treated with chemotherapy and cord blood stem cell transplantation twice. Although he had neither blast cells in the peripheral blood nor leucocytosis, urgent bronchoscopy findings demonstrated blast cells invading both the alveolar spaces/alveolar septa and the vein walls. These pathological findings corresponded to ground-glass opacities and thickening of the interlobular septa on thoracic computed tomography (CT). In acute lymphoblastic leukaemia/lymphoblastic lymphoma patients presenting with infiltrates on thoracic CT, leukaemic pulmonary involvement should be considered in the differential diagnoses, even in the absence of hyperleucocytosis or blast cells in the blood, similar to pulmonary involvement in myeloid leukaemias.