A 5 year old child presents with history of fever off and-on for past 2 weeks and petechial spots all over the body and increasing pallor for past 1 month. Examination reveals splenomegaly of 2 ems below costal margin. The most likely diagnosis is -
Acute leukemia
Idiopathic thrombocytopenic purpura
Hypersplenism
Aplastic anemia