We present here a new case of the hematological malignancy in a-5-years-old boy.  
The main clinical sign was pancytopenia.  
The punction of the sternum followed by biopsy was performed.  
On cytological smear, blasts with large nuclei (without prominent nucleoli) and scanty cytoplasm were seen.  
The biopsy specimen was not appropriate since it mainly contained a bone structures with very few areas of bone marrow elements. Nevertheless, we also noticed the presence of large blast cells with large, oval nuclei and prominent, centrally located nucleoli and moderately abundant cytoplasm.  
Special stainings: PAS (negative)  
IHQ: CD34 (positive), MPO (positive), CD10 (negative), CD79a (negative), CD45RA (negative), CD3 (negative), TdT (not available at the moment).  
Differential diagnosis: Acute lymphoblastic or myelogenous leukemia?  
Our preliminary diagnosis: Acute myelogenous leukemia (AML).  
Please, give your opinions.