AGGRESSIVE ACUTE CD3(-) T-CELL LARGE GRANULAR LYMPHOCYTE LEUKEMIA WITH 2 STAGES OF MATURATION ARREST(), CD56()

In the majority of clonal expansions of CD3(+) large granular lymphocy tes (LGL), referred to as T-LGL leukemia, patients have a chronic dise ase, often manifested by severe neutropenia, rheumatoid arthritis, and mild to moderate splenomegaly. The characteristic leukemic phenotype is CD3(+), CD8(+), CD16(+), CD57(+) and CD56(-). Here we report an unu sual case of T-LGL (CD3cyt(+), CD3surface(-), CD16(+), CD56(-)) with c linicopathological features (acute presentation, large tumor mass, and systemic illness with highLGL counts at diagnosis) similar to those d escribed for patients with CD3-natural killer (NK)-LGL leukemia. Two d istinct stages of maturation arrest were observed: in the lymph node a bnormal cells were CD4+, CD8+ whereas the majority of circulating leuk emic cells expressed only CD8. TCR gamma (TCR gamma) gene configuratio n demonstrated that these originated from the same T cell clone, sugge sting a maturation process between the two populations, or preferentia l passage of CD8 single positive cells into the blood.