Natural Killer Cell Lymphoma: A Case with Classification Dilemma.

Non-Hodgkins lymphoma of the Natural Killer (NK) cell type is rare. World Health Organisation recognises 3 NK-cell phenotypic entities; extranodal NK/T cell lymphoma, nasal type (ENK/TL); aggressive NK cell leukaemia (ANKL); and chronic lymphoproliferative disorders of NK cells (CLPD-NK) which is classified as a provisional entity. Though specific clinical, morphological and immunophenotypic criteria have been laid down to diagnose these conditions there may however, be considerable variations in the clinical presentation making diagnosis difficult. We present a case with contrasting clinical and haematopathological findings posing difficulty in its diagnosis and classification, and despite the aggressive presentation showing favourable response to treatment.