This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pathology
Hairy cell leukemia&; is a Neoplastic proliferation of : 
Select and explain. 
A. T. cells, B. B. cells, C. Myeloid cells, D. Macrophages
B: B. cells
Answer: B: B. cells 
Explanation: Hairy cell leukemia review : Presentation is with a triad of : Splenomegaly :often massive. However hepatomegaly is less common while lymphadenopathy is rare. Pancytopenia and thereby, resulting infections. Vasculitis like syndrome :Erythema nodosum and cutaneous nodules due to perivasculitis and PAN. Course : Hairy cell leukemia follows an indolent course. REF: ROBBINS pathology 10th edition