Aggressive natural killer cell leukaemia: a rare and fatal disorder.

Natural killer (NK) cell neoplasms, which include extra-nodal NK/T-cell lymphoma (nasal and extra-nasal) and aggressive NK cell leukaemia, are generally rare, but they are more common in people of Oriental, Mexican and South American descent. These neoplasms are highly aggressive, and show a strong association with Epstein-Barr virus. Aggressive NK cell leukaemia affects younger patients, who present with poor general condition, fever, and disseminated disease; they often die within a short time from systemic disease or complications such as multi-organ failure. Aggressive NK cell leukaemia must be distinguished from T-cell large granular lymphocyte leukaemia and indolent NK cell lympho-proliferative disorder, both of which are indolent. We present a case of young Asian male with aggressive NK cell leukaemia who presented with a poor general condition and disseminated disease. The patient had a rapidly progressive disease and died within weeks of diagnosis.