Laboratory findings in CD4(+) large granular lymphocytoses.

Large granular lymphocytic (LGL) leukemia is an uncommon disorder of mature T or natural killer (NK) cells. Most T-LGL proliferations are CD3(+)/CD8(+), although rare CD4(+) clonal T-LGL expansions have been reported. We report the clinicopathologic features of eight patients with aberrant CD4(+), cytotoxic T-cell lymphocytoses. Median follow-up was 29 months (range 8-100), during which all were alive without requirement for therapy. Four of eight patients had an additional malignancy; none had a history of rheumatoid arthritis, lymphadenopathy or hepatosplenomegaly. Morphologic expansions of granulated lymphocytes were evident in 6/8. All had immunophenotypically aberrant populations of CD4(+) T cells with uniform, moderate or bright CD56. Seven of eight expressed CD57, and four were CD8(partial dim +). Abnormal levels of expression of two or more T-cell antigens were seen in all cases. All tested cases were Tgamma PCR positive. Our results support that CD4(+) T-LGL lymphocytosis is a clonal disorder with clinicopathologic characteristics distinct from the more common CD8(+) variant.