T-Cell Large Granular Lymphocytic Leukemia with Atypical Immunophenotypes: A Single Center Retrospective Analysis of 17 Cases

Abstract Purpose T-cell large granular lymphocytic leukemia (T-LGLL) is characterized by expansion of cytotoxic T cells expressing αβ T cell receptor (TCR), CD2, surface CD3, CD8, CD57 as well as cytotoxic molecules. Atypical immunophenotypes of T-LGLL, including γδ TCR and CD4, reported in a small subset, remains to be well-defined. Methods We retrospectively analyzed immunophotypes and clinicopathologic features of 96 T-LGLL cases. Results We found a total of 17 cases with atypical immunophenotypes including 9 TCRγδ + cases and 8 CD4+ TCRαβ + cases. Pure red cell aplasia was less common in atypical immunophenotypes patients compared to that of typical immunophenotypes [0/17 (0%) vs. 26/79 (32.9%), p=0.005]. STAT3 mutations were also less frequent in atypical immunophenotypes cases, although accompanied with marginal significance (p=0.086). Conclusion Patients with atypical immunophenotypes showed a similar survival outcome to that of typical T-LGLL immunophenotypes. Additional efforts were needed to better understand the pathogenesis of these rare atypical immunophenotypes T-LGLL cases.