This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anemia and RBC Disorders, Subject name: Medicine
Splenomegaly is a feature of all except: 
Select and explain. 
A. Aplastic anemia, B. CML, C. Thalessemia, D. Hypersplenism
A: Aplastic anemia
Answer: A: Aplastic anemia 
Explanation: Ans: A (Aplastic anemia) Ref: Harrison's 18th edn, pg 467Explanation:Aplastic anemia is pancytopenia w ith hypocellular bone marrow. It does not produce any organomegaly.Causes of massive splenomegaly :CMLMyelofibrosisHairy cell leukemiaChronic malariaKala azarExtrahepatic portal vein thrombosisOther causes:Acute malariaTyphoidInfectious mononucleosisInfective endocarditisLeptospirosisTuberculosisViral hepatitisHIVSLERheumatoid arthritisHIVHemolytic anemiaMechanisms of Splenomegaly:Hypertrophy/hyperplasia related to specific splenic function: RES hyperplasia in hereditary- spherocytosis, thalassemia; immune hyperplasia as in infectious mononucleosis. SLEPassive congestion: As in portal hypertensionInfiltrative diseases: Lymphomas, Myelopro-liferative disorders