Clinicopathologic features of aggressive natural killer cell leukemia

Abstract

To study the clinicopathologic features of aggressive natural killer cell leukemia (ANKL). The clinical and pathologic features were analyzed in 10 patients with ANKL. The complete blood count, peripheral blood smears, bone marrow aspirates and bone marrow biopsies were studied. Immunophenotypic analysis was carried out by flow cytometry and immunohistochemistry. T-cell receptor (TCR) γ gene rearrangement was studied by PCR method. The most frequent hematologic abnormalities observed were anemia (7 cases) and thrombocytopenia (9 cases). Large granular lymphocytes were found on peripheral blood smears of 6 patients. In bone marrow aspirates, lymphocytosis (> 20.0%) was demonstrated in 8 cases and large granular lymphocytes in 6 cases. Bone marrow biopsies revealed various degrees of neoplastic infiltration, as follows: mild (5 cases), moderate (3 cases) and severe (2 cases). The neoplastic cells were mainly interstitial in distribution in 8 cases and diffuse in 2 cases. Hemophagocytosis was observed in 4 cases. Flow cytometry showed CD2+ sCD3- CD4- CD56+ CD57- in all cases, CD7+ in 9 cases, CD16+ in 5 cases, CD8+ in 4 cases and CD5+ in 1 case. Immunohistochemistry performed in 8 cases showed the following results: cCD3+ in 4 cases, CD56+ in 6 cases, TIA-1+ in 6 cases, granzyme B+ in 4 cases and perforin+ in 2 cases. PCR study revealed germline TCRγ gene configuration in all cases. ANKL is a highly aggressive NK cell-derived lymphoid neoplasm. Comprehensive morphologic, immunophenotypic and molecular analysis are essential in arriving at a correct diagnosis. ANKL needs to be distinguished from other types of NK-cell and T-cell lymphomas.