Clinical, Morphologic, Immunophenotypic, and Molecular Cytogenetic Assessment of CD4–/CD8– γδ T-Cell Large Granular Lymphocytic Leukemia

γδ T-cell large granular lymphocytic (T-LGL) leukemia of the CD4–/CD8– subtype is rare, and data are limited in the literature. This study evaluated the clinical, morphologic, immunophenotypic, and molecular cytogenetic features of 7 cases of CD4–/CD8– γδ T-LGL leukemia. Although this variant shares several clinical and morphologic features with the more common T-LGL leukemias, the incidences of autoimmune hemolytic anemia and pure red cell aplasia are higher. Another striking feature observed in our study was the lack of increased large granular lymphocytes in the peripheral blood in the majority of cases despite prominent bone marrow or splenic involvement. CD4–/CD8– γδ T-LGL leukemia also displays an immunophenotype and pattern of splenic involvement overlapping with hepatosplenic T-cell lymphoma. Clinically, this variant of T-LGL leukemia shows an overall indolent course, but treatment is often required in the initial stages of the disease. Awareness of these features is important for early recognition and accurate diagnosis of patients with CD4–/CD8– γδ T-LGL leukemia.