CD 19 positive, CD22 positive, CD103 positive monoclonal B-cells with bright kappa positivity were found to comprise 60% of the peripheral blood lymphoid cells on flow cytometric analysis in a 55 year old man with massive splenomegaly and a total leucocyte count 3.3 x 109/L. Which one of the following is the most likely diagnosis -

Hairy cell leukaemia: Constitutes about 2% of all leukaemia. Male:female: :5:1,middle aged white males predominant , median age :55; Immunophenotype: typically express pan-Bcell markers CD19&CD20, surface Ig(usually IgG) & ceain relatively distinctive markers , such as CD11c,CD25 ,CD103 and annexin A1. Ref:Robbins pathologic basis of disease ,pg:603,604