Aggressive natural killer cell leukemia presenting with hemophagocytic lymphohistiocytosis.

Aggressive natural killer cell leukemia (ANKL) is a very rare condition and when reported occurs almost exclusively in adults. We report a pediatric case of ANKL that presented with hemophagocytic syndrome, preceding the onset of leukemia by 12 weeks. Clinical and laboratory findings are discussed, along with morphology, immunophenotyping and cytogenetics, as well as the association with Epstein-Barr virus (EBV). This case is noteworthy for the expression of CD8 on the malignant cells, the cytogenetic findings that include abnormalities of chromosomes 6 and 7, as well as the age of the patient.