This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Splenomegaly is least likely associated with aEUR' 
Select and explain. 
A. CML, B. Polycythemia ruba vera, C. Idiopathic myelofibrosis, D. Primary thrombocytosis
D: Primary thrombocytosis
Answer: D: Primary thrombocytosis 
Explanation: Primary thrombocytosis The question is about the differential diagnosis of myeloprohferative syndrome. - Myeloproliferative disorders are characterized by splenomegaly except for essential thrombocytosis. In Essential thrombocytosis - "Physical examination is generally unremarkable except occasionally for mild splenomegaly. Massive splenomegaly is more indicative of another myeloproliferative disorder in paicular polvcythetnia vera, idiopathic mvelofibrosis and chronic myeloid leukemia".