Aggressive NK-cell leukemia: A rare entity with diagnostic and therapeutic challenge

Aggressive natural killer cell leukemia (ANKL) is a rare neoplasm of mature natural killer cells, with an extremely poor overall survival, which is almost always EBV related, with majority of cases reported in East Asia. Here we report the case of an ANKL presenting in a young Hispanic male with secondary hemophagocytosis. Aggressive clinical course, high EBV DNA levels and leukemic presentation, often with associated hemophagocytosis, should raise suspicion of an NK/T-cell neoplasm like ANKL. Due to significant diagnostic overlap with extranodal NK/T-cell lymphoma, nasal type (ENKL), accurate diagnostic classification is crucial due to differing treatment and prognosis. L-asparaginase including chemotherapy followed by allogeneic stem cell transplantation appears to slightly prolong overall survival, but relapse is almost inevitable. Clinical monitoring of EBV DNA levels shows good correlation with disease activity.