CD4 positive/CD8 negative/CD56 positive T cell large granular lymphocyte proliferations; clonal disorders of uncertain significance

Background Clonal expansions of CD4 positive T large granular lymphocytes with or without co-expression of CD8 are extremely uncommon. These typically display an indolent clinical course and are said to be associated with other solid malignancies. We present the clinicopathologic features and immunophenotypic analyses of two rare cases of CD4 positive T large granular lymphocyte proliferation with expression of natural killer cell associated antigen CD56. Both had high positive anti cytomegalovirus (CMV) IgG titres and persistent lymphocytosis with a relatively benign course at 15 and 13 months of follow up, respectively.