Extensive but Steroid-sensitive Pulmonary Infiltration by Natural Killer-large Granular Lymphocytic Leukemia

Abstract

A 51-year-old woman with persistent proliferation of natural killer (NK) cells in her peripheral blood was diagnosed with NK-large granular lymphocytic leukemia (NK-LGLL). During follow-up, computed tomography revealed multiple infiltrative pulmonary lesions. A flow cytometric analysis of bronchoalveolar lavage fluid showed infiltration of NK cells, resulting in a diagnosis of pulmonary infiltration by NK-LGLL. A histological examination of thoracoscopic lung biopsy specimens supported this diagnosis. She was started on 1 mg/kg prednisolone, which resulted in a durable reduction in these lesions. This is the first report of a NK-LGLL patient with pulmonary infiltration who received medication. Furthermore, treatment with prednisolone alone was successful.