A 5 year old boy is brought to the ER by his parents for fev…

A 5 yeаr оld bоy is brоught to the ER by his pаrents for fever, bruising, coughing, аnd weakness. On physical examination, he had a palpable spleen and multiple bruises over his lower extremities. He was admitted to the hospital. Laboratory tests including a CBC with differential, PT/INR, PTT, and a complete metablolic panel were ordered. A bone marrow examination was also performed. His test results revealed the following: WBC= 3x10^9/L MCV=84 MCH=29 MCHC=32g/dL Platelets= 10x10^9/L Hgb=7.1 Hct=21.3 Cytochemical Studies Peroxidase= Negative Nonspecific esterase= Negative TdT= Strongly positive Surface Markers CD 10= positive CD19= positive What is the most likely diagnosis?