Flow Cytometry in Mature T- and NK-cell Neoplasms: A Retrospective Descriptive Study from a Tertiary Care Cancer Centre in Kerala, India

for continuous variables and frequencies and percentages for categorical variables were obtained. The Kaplan-Meier method for survival plots was used. Results: Mature T- and NK-cell neoplasms constituted 83 cases. The median age of patients was 56 years. The majority of patients were males (n=49). Adult T-cell Leukaemia/Lymphoma (ATLL) (n=50) constituted the most common subtype, followed by Mycosis fungoides/Sezary syndrome (MF/SS) (n=14), T-cell Large Granular Lymphocytic Leukaemia (T-LGLL) (n=7), T-cell Prolymphocytic Leukaemia (T-PLL) (n=4), Aggressive NK-cell Leukaemia (ANKL) (n=3), Hepatosplenic T-cell Lymphoma (HSTL) (n=3), and Anaplastic Large Cell Lymphoma (ALCL) (n=2). OS and PFS at three years were 22.3% and 16.6%, respectively. Conclusion: Mature T- and NK-cell neoplasms presenting as leukaemia is rare. ATLL was the most common subtype of MTNKN. Flower cells, Sezary cells, and prolymphocytes are useful morphological clues for diagnosis. Immunophenotyping by flow cytometry, along with clinicopathologic correlation, is crucial for the diagnosis and subclassification of MTNKN. All subtypes except T-LGLL show inferior PFS and OS.