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
All of the following NHL involve the white pulp of spleen Except 
Select and explain. 
A. Hairy cell leukemia, B. Burkitt lymphoma, C. Follicular lymphoma, D. Mantle cell lymphoma
A: Hairy cell leukemia
Answer: A: Hairy cell leukemia 
Explanation: Hairy cell leukemia is a rare, slow-growing cancer of the blood in which your bone marrow makes too many B cells (lymphocytes), a type of white blood cell that fights infection. These excess B cells are abnormal and look "hairy" under a microscope.