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 αß 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)-αß 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.

Atypical Mature T-Cell Neoplasms: The Relevance of the Role of Flow Cytometry.

Lymphoproliferative disorders are a heterogeneous group of malignant clonal proliferations of lymphocytes whose diagnosis remains challenging, despite diagnostic criteria are now well established, due to their heterogeneity in clinical presentation and immunophenotypic profile. Lymphoid T-cell disorders are more rarely seen than B-cell entities and more difficult to diagnose for the absence of a specific immunophenotypic signature. Flow cytometry is a useful tool in diagnosing T-cell lymphoproliferative disorders since it is not only able to better characterize T-cell neoplasms but also to resolve some very complicated cases, in particular those in which a small size population of neoplastic cells is available for the analysis. Here, we report three patients with mature T-cell neoplasms with atypical clinical and biological features in which analysis of peripheral blood and bone marrow specimens by means of multicolor flow cytometry was very useful to identify and characterize three rare T-cell lymphoproliferative disorders, such as angioimmunoblastic T-cell lymphoma, peripheral T-cell lymphoma not otherwise specified and T-cell prolymphocytic leukemia. The aim of this case series report is not only to describe three rare cases of lymphoproliferative neoplasms but also to raise awareness that a fast, highly sensitive, and reproducible procedure, such as flow cytometry immunophenotyping, can have a determinant diagnostic role in these patients.