Flow cytometric immunophenotypic profiles of mature gamma delta T-cell malignancies involving peripheral blood and bone marrow

Background: In this study we compared clinical findings with flow cytometric immunophenotypic results in a series of patients with aggressive and indolent gamma delta T-cell malignancies with peripheral blood and/or bone marrow involvement. Methods: Gamma delta T-cell malignancies were detected based on flow cytometric demonstration of an abnormal T-cell population staining positive with T-cell receptor gamma delta and confirmed by morphologic and clinical reviews. Clinical data were obtained through chart review and discussion with the patients' physicians. Results: Blood or bone marrow involvement was present in all patients. Hepatosplenic and cutaneous gamma delta T-cell lymphomas had an aggressive clinical course, whereas the gamma delta T-cell large granular lymphocyte (LGL) leukemias had an indolent course. Expressions of CD5, CD8, CD16, and CD57 differed in gamma delta T-cell LGL leukemia compared with hepatosplenic and cutaneous gamma delta T-cell lymphomas. Conclusions: Gamma delta T-cell malignancies have a poor prognosis with the exception of gamma delta T-cell LGL leukemia (indolent process). Because CD57 expression is specific for gamma delta T-cell LGL leukemias, expression of this antigen may be associated with a more indolent clinical course. Because cutaneous gamma delta T-cell lymphoma can present with peripheral blood involvement, flow cytometric evaluation of peripheral blood is important in staging these patients.