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: Medicine
CLL is differentiated from Mantle Cell Lymphoma by 
Select and explain. 
A. CD 5, B. CD 17, C. CD22, D. CD 23
D: CD 23
Answer: D: CD 23 
Explanation: Mantle cell lymphoma (MCL) and chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) share many morphologic and immunophenotypic features. In addition to histomorphologic examination, it is customary to use the absence of CD23 to differentiate MCL from CLL/SLL. ref - Harrisons internal medicine 20thediton pg764-767