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
[{'content': 'Hairy cell leukemia&; is a Neoplastic proliferation of : \nSelect and explain. \nA. T. cells, B. B. cells, C. Myeloid cells, D. Macrophages', 'role': 'user'}, {'content': 'Answer: B \nExplanation: 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', 'role': 'assistant'}]