Rare aggressive natural killer cell leukemia presented with leukopenia and disseminated intravascular coagulation—a diagnostic challenge

Aggressive natural killer cell leukemia/lymphoma (ANKL) is a rare and aggressive malignancy of natural killer (NK) cells. It is now regarded as a distinct subtype of leukemia as a provisional entity: “NK cell lymphoblastic leukemia/lymphoma” in the 2016 revision to the World Health Organization classification. It is important to diagnose ANKL early due to its fulminant clinical features that may rapidly progress to multiorgan failure (MOF). However, there is no definite diagnostic marker of the disease so it is difficult to make differential diagnosis from other lymphoproliferative disorders. The case reported here is of a 27-year-old male patient who initially presented with leukopenia, disseminated intravascular coagulation (DIC), and MOF during the early stages of illness, and a diagnosis of ANKL was made after a series of examinations. He had no opportunity to take chemotherapy due to the extremely short and aggressive disease course. To the best of our knowledge, this was the first case with ANKL reported from our hospital and the second case from Turkey.