This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Pathology
[{'content': '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 - \nSelect and explain. \nA. Splenic lymphoma with villous lymphocytes, B. Mantle cell lymphoma, C. B-cell prolymphocytic leukemia, D. Hairy cell leukemia', 'role': 'user'}, {'content': 'Answer: D \nExplanation: 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', 'role': 'assistant'}]