Non-EBV-Related Aggressive NK-Cell Leukemia: An Oncohematological Great Imitator.

Aggressive natural killer (NK)-cell leukemia (ANKL) is a very rare oncohematological disease among youngsters in Latin America. Its clinical picture imitates a variety of syndromes and diseases due to its pathophysiology. Its diagnosis is relatively simple due to the prominence of NK malignant cells in peripheral blood and its clinical aggressiveness. In certain circumstances though, the presence of blast NK cells and the natural course of the disease can be so modified by the treatment of one of the imitated diseases, especially when using steroids, that it becomes very difficult to diagnose early in its course. We present a case of a 16-year-old Mexican male who initiated symptoms imitating dengue to severe dengue for which he received steroids, apparently inducing a partial remission; he was then diagnosed as having community acquired pneumonia, then sepsis, septic shock w/disseminated intravascular coagulation, primary hemophagocytic syndrome, severe hepatitis, lupus and finally hyper IgE. It was not until 1 day before dying of hemorrhagic shock, a month after initiating symptoms, when the (re)emergence of blast NK cells in peripheral blood allowed the correct diagnosis to be made. Knowledge of ANKL pathophysiology may raise awareness of this multifaceted malignancy and may open up possibilities for its therapy. Gained knowledge can also be used for guiding NK cell evident aggressiveness against other malignancies.