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 cm below costal margin. The most likely diagnosis is -

Acute myeloid leukemia is a heterogeneous disease characterised by infiltration of malignant myeloid cells into the blood,bone marrow & other tissues. It is characterised by anemia(producing pallor,lethargy,dyspnoea), bleeding manifestations(petechiae,bruises,bleeding from gums), pain & tenderness of bones, lymphadenopathy, splenomegaly, hepatomegaly, gum hyperophy, chloroma or granulocytic sarcoma, meningeal involvement causing raised intracranial pressure .Reference:Harsh mohan textbook of pathology sixth edition pg no 363.