Lymphoproliferative disorders of natural killer cells: report of two cases and review of literature.

Lymphoproliferative disorders of natural killer cells (LPD-NK) are rare lymphoproliferative diseases involving NK cells. Here, we present two cases of LPD-NK. The first case is a 63-year-old man who presented with high fever, cytopenia, and a history of myelodsyplastic syndrome. He was finally diagnosed with aggressive NK cell leukemia and died due to progression of the disease within 15 days of diagnosis. The second case is a 70-year-old man with granulocytopenia who did not have clinical manifestations; he was diagnosed with chronic lymphoproliferative disorder of NK cells and a watch and wait approach was adopted until six-month follow up. This article describes the clinical features, pathogenesis, diagnosis, treatments, and prognosis of LPD-NK through a literature review of case reports.