AGGRESSIVE NATURAL-KILLER-CELL LYMPHOMA LEUKEMIA - A RECENTLY RECOGNIZED CLINICOPATHOLOGICAL ENTITY

We report a comprehensive study of a case of aggressive natural killer cell lymphoma/leukemia, which is characterized by young male predomin ance, rapidly progressive clinical course, and presence of lymphadenop athy, hepatosplenomegaly, and bone marrow involvement. The leukemic ph ase is frequently preceded by pancytopenia. The diagnostic clues are t he detection of cytoplasmic granules in tumor cells on Wright-Giemsa-s tained tissue imprints or smears and a selective loss of T-cell antige ns. Immunophenotyping is decisive in making the final diagnosis by sho wing positive natural killer cell markers (CD 16, CD56, and/or CD57), CD2, CD11c, and Ia, but negative CD3, T-cell receptor heterodimers, te rminal deoxynucleotidyl transferase, and B-cell markers. Genotyping al ways shows germline configuration in both immunoglobulin and T-cell re ceptor genes. The unique feature in this case is its presentation as a testicular lymphoma, which has not been previously reported. Polymera se chain reaction was performed in this case but failed to detect huma n T-cell leukemia virus type I/II provirus. It is important to recogni ze this new entity as it is a highly aggressive disease with a rapidly progressive clinical course and fails to respond to any chemotherapeu tic regimen available.