The Value of Flow Cytometry Clonality in Large Granular Lymphocyte Leukemia

T-Large Granular Lymphocytic Leukemia with Hepatosplenic T-Cell Lymphoma? A Rare Case of Simultaneous Neoplastic T-Cell Clones Highlighted by Flow Cytometry and Review of Literature

Lymphoproliferative diseases are a heterogeneous set of malignant clonal proliferations of lymphocytes. Despite well-established diagnostic criteria, the diagnosis remains difficult due to their variety in clinical presentation and immunophenotypic profile. Lymphoid T-cell disorders are less common than B-cell entities, and the lack of a clear immunophenotypic characteristic makes their identification hard. Flow cytometry turned out to be a useful tool in diagnosing T-cell disorders and to resolve complicated cases, especially if the number of analyzable neoplastic cells is small. We present a case of a 55-year-old man with simultaneous lymphoproliferative neoplastic T-cell clones, one αβ and the other γδ, identified and characterized by flow cytometry (FC), exploiting the variable expression intensity of specific markers. However, the patient's rapid decline made it impossible to define a differential diagnosis in order to confirm the identity of the γδ clone, which remains uncertain. This case is added to the few other cases already documented in the literature, characterized by the co-existence of T-large granular lymphocytic leukemia (T-LGLL)-αβ and T-LGLL-γδ/Hepatosplenic T-cell lymphoma (HSTCL). Our case underlines the key role of sensitive diagnostic tools in the assessment of potential relationship between the diagnosis, prognosis, and treatment in the two pathologies.

Molecular Features and Diagnostic Challenges in Alpha/Beta T-Cell Large Granular Lymphocyte Leukemia

Large granular lymphocyte leukemia is a rare chronic lymphoproliferative disease of cytotoxic lymphocytes. The diagnosis, according to the WHO, is based on a persistent (>6 months) increase in the number of LGL cells in the peripheral blood without an identifiable cause. A further distinction is made between T-LGL and NK-LGL leukemia. The molecular sign of LGL leukemia is the mutation of STAT3 and other genes associated with the JAK/STAT pathway. The most common clinical features are neutropenia, anemia, and thrombocytopenia, and it is often associated with various autoimmune conditions. It usually has an indolent course. Due to the rarity of the disease, no specific treatment has yet been identified. Immunosuppressive therapy is used and may allow for disease control and long-term survival, but not eradication of the leukemic clone. Here, we discuss the clinical presentation, diagnostic challenges, pathophysiology, and different treatment options available for alpha/beta T-LGL leukemia, which is the most common disease (85%), in order to better understand and manage this often misunderstood disease.

T cell clonal expansion and STAT3 mutations: a characteristic feature of acquired chronic T cell-mediated pure red cell aplasia

Acquired chronic pure red cell aplasia (PRCA) develops idiopathically or in association with other medical conditions, including T cell large granular lymphocytic leukemia (T-LGLL) and thymoma. T cell dysregulation is considered a cardinal pathogenesis of PRCA, but genetic-phenotypic associations in T cell abnormalities are largely unclear. We evaluated an extended cohort of 90 patients with acquired PRCA, including 26 with idiopathic, 36 with T-LGLL-associated and 15 with thymoma-associated PRCA, for their T cell immuno-phenotypes, clonalities and STAT3 mutations. TCR repertoire skewing of CD8⁺ T cells was detected in 37.5% of idiopathic, 66.7% of T-LGLL-associated and 25% of thymoma-associated PRCA patients, and restriction to Vβ1 was most prominent (41%). Clonalities of TCRβ or γ chain and STAT3 mutational status were statistically associated (P = 0.0398), and they were detected in all three subtypes. The overall response rate to cyclosporin A was 73.9%, without significant difference by subtypes nor STAT3 mutational status. The T cell dysregulations, such as TCR repertoire skewing with predominant Vβ1 usage, clonality and STAT3 mutations, were frequently found across the subtypes, and the close associations between them suggest that these T cell derangements reflect a common pathophysiological mechanism among these PRCA subtypes.