Proliferations of T-cell large granular lymphocytes (T-LGL) are a rare and heterogeneous disease entity characterized by a chronic course, cytopenias and circulating cytotoxic T lymphocytes. We present the results of a single institution retrospective review of the clinical presentation of T-LGL proliferations. A total of 23 patients evaluated for cytopenias were identified as having T-LGL by flow cytometry, ten male and thirteen female, with a median age of 67 years at diagnosis. Twelve patients had a prior malignancy (non-Hodgkins lymphoma=4, MDS/AML=4, breast cancer=2, squamous cell cancer (SCC) of the skin =2, lung SCC=1, vocal cord SCC=1, uterine cancer=1) and five patients had a history of autoimmune disease (rheumatoid arthritis=2, vasculitis=1, polyarthritis=1, Wegener’s granulomatosis=1), while seven patients had no previous history of autoimmune disease or malignancy. Four patients with prior malignancy had active disease and this led to death in three. Of the twelve patients informative for T-cell receptor gene rearrangements, clonal populations were found in eight. All patients who had cytopenias requiring treatment were initially treated with cyclosporine monotherapy, with the further addition of growth factors if necessary.

Multiparameter flow cytometric analysis of blood or bone marrow aspirates revealed that patients with a prior history of systemic malignancy had the common immunophenotype of CD3+(h), CD8+(h), CD2+, CD5+, CD7(h), CD56(h), CD57+, CD38+, CD16−. In contrast, patients who did not have a prior history of malignancy were CD3+, CD8+, CD2+, CD5+, CD7+, CD56+/−, CD57+, CD38+/(h), CD16+/− (h=heterogeneous). Thus patients with a prior malignancy had more heterogeneous expression of the T-cell markers CD3, CD8 and CD7 and were less likely to express CD16. We conclude that prior malignancy is more common in patients with T-LGL proliferations than previously recognized, may be twice as frequent as autoimmune disease in association with T-LGL and may have a distinct immunophenotype. Our data suggest that malignant cells may induce proliferations of T-LGL.

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