<prompt> An elderly male presents with anemia and fatigue. OE splenomegaly-2 cm palpable below costal margin. Hemogram showed Pancytopenia. Which is the most common etiology?Hairy cell leukemiaCMLThalassemiaFollicular lymphoma  <response>: Ans. a Hairy cell leukemiaRef: R 9thpg 603-604In the given scenario an elderly male presents with Anemia, Splenomegaly Pancytopenia.Discussing the options one by one:Hairy cell Leukemia: Chronic B-cell leukemia characterized by hairy cells, pancytopenia and splenomegaly QCML: Massive splenomegaly with Basophilic Leukocytosis seenThalassemia: Jaundice, severe anemia requiring transfusion, hepatosplenomegaly with leukoerythroblastosis, usually presents in childhoodFollicular lymphoma: Lymphadenopathy - Leukocytosis 