<prompt> Hairy cell leukemia; is a Neoplastic proliferation of :T. cellsB. cellsMyeloid cellsMacrophages  <response>: 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 