A 12 yrs old girl complains of pain persisting in her leg for several weeks with a low grade fever.A radiograph reveals a mass in the diaphyseal region of the left femur with overlying cortical erosion and soft tissue extension.A biopsy of the lesion shows numerous small round cells,rich in PAS positive diastase sensitive granules.The most likely histological diagnosis is:

A 12 yrs old girl complains of pain persisting in her leg for several

1.	A 12 yrs old girl complains of pain persisting in her leg for several weeks with a low grade fever.A radiograph reveals a mass in the diaphyseal region of the left femur with overlying cortical erosion and soft tissue extension.A biopsy of the lesion shows numerous small round cells,rich in PAS positive diastase sensitive granules.The most likely histological diagnosis is:
A.	Osteogenic sarcoma
B.	Osteoblastoma
C.	Ewing's sarcoma
D.	Chondroblastoma
Answer» D. Chondroblastoma