T-cell large granular lymphocytic leukemia is a rare form of leukemia, caused by clonal proliferation of cytotoxic T-cells, characterized by modest lymphocytosis and cytopenias of other lineage with hepatosplenomegaly and relatively rare lymph nodal involvement. Involvement of other organs is extremely rare. It is predominantly an indolent disease and most of patients remain asymptomatic for a long period. We present a rare case of aggressive form (CD56 positive) of large granular lymphocytic leukemia with atypical presentations mimicking pleural malignancy on F-FDG PET/CT.