“T-cell prolymphocytic leukemia (T-PLL), a heterogeneous disease exemplified by two cases and the important role of cytogenetics: a multidisciplinary approach”

T-cell prolymphocytic leukemia (T-PLL) is a rare mature T-cell lymphoproliferative disorder, which suppresses the immune system through multifactorial processes, thus predisposing the affected patient to a variety of infections, and possibly death [1-3]. Common cytogenetic abnormalities in T-PLL usually include 14q11.2, chromosome 8 rearrangements, 11q abnormalities leading to the deletion of the ATM and MLL genes, and abnormalities on 12p, 5q, 6q and 13q [3-8]. The presence of a combination of these fairly unique structural genetic abnormalities makes chromosome analysis very crucial and extremely helpful to get an accurate and definitive diagnosis of T-PLL as it supplements the immunophenotypic and morphological data. Herein, we present two distinct and diagnostic challenging cases of T-PLL that emphasize the heterogeneity of this disease but showed cytogenetic aberrations that helped to confirm the diagnosis of T-PLL. In addition, we stress the importance of a multidisciplinary approach using the morphologic analysis, flow cytometry, cytogenetic and FISH to accurately diagnose this disease.CASE #1 is an 84 year old male who presented for routine check-up and was found to have an elevated white cell count (WBC) of 22.3×10E3/uL. Peripheral blood (PB) smear showed lymphocytosis that appeared small to intermediate in size with mildly abundant cytoplasm, round to ovoid nuclear contours, and inconspicuous nucleoli. Some showed cytoplasmic blebs (Figure 1A). Flow cytometry of the PB revealed that these atypical lymphocytes were of mature phenotype lacking TdT expression and were positive for alpha-beta T-cell receptor. In addition, the neoplastic T-cells showed bright expression of CD8 and moderate uniform expression of CD52 but no significant loss of pan T-cell antigens was noted (Figures 2A, 2C).A bone marrow (BM) biopsy revealed an inconspicuous infiltrate of atypical lymphocytes that were highlighted by a TCL1 immunostain and a diagnosis of 10% involvement of the ma