Abstract：Objective: To describe the difference of the clinical symptoms and radiologic features between Ewing sarcoma(ES) and peripheral primitive neuroectodermal tumors(pPNETs) of bone, and to benefit from the differential diagnosis and treatment. Materials and Methods: We retrospectively reviewed 18 cases of ES and 10 cases of pPNETs all were confirmed pathologically. Radiologic and clinical studies were reviewed by two musculoskeletal radiologists. In ES, radiographs(n=18), CT(n=12), MRI(n=9) were performed. In pPNETs, radiographs(n=10), CT(n=7), MRI(n=10) were performed too. The evaluation included clinical presentation,lesion location and size,bone erosion/destruction,periosteal reaction, soft tissue involvement and intrinsic characteristic findings on CT and MRI. Results: Patients’ average age was 18.5 years (range 10～28) and 24.4 years(range 8～86) in ES and pPNETs respectively. For the ES, the lesion locations included femur(n=6), humerus(n=4), clavicle(n=2), tibia(n=1), fibula(n=1), ulna(n=1), ilium(n=1), sacrum(n=1) and acetabulum(n=1); Radiographs(n=18) showed lytic lesion(7/18), with irregular sclerosis and matrix mineralization(11/18), soft tissue mass(10/18), periosteal reaction(10/18), eccentric(6/18), scalloping of cortex(3/18); CT(n=12) showed lytic lesion(4/12), lesion with irregular sclerosis and matrix mineralization(8/12), soft tissue mass(10/12), periosteal reaction(6/12); On MRI(n=9), T1WI showed isointensity(8/9) and slightly hyperintensity(1/9), T2WI and STIR images showed heterogeneous hyperintensity(9/9), soft tissue mass(8/9), the size ranged from 2cm×3cm to 3cm×10cm. For the pPNETs, the lesion locations included ilium(n=3), humerus(n=2), corpus vertebrae(n=1), arcus vertebrae(n=1), scapula(n=1), sacrum(n=1), sphenoid(n=1); Radiographs(n=10) showed lytic lesion(8/10), with irregular sclerosis and dilation(1/10), and normal(1/10), soft tissue mass(7/10), periosteal reaction(0/10). CT(n=7) showed lytic lesion(6/7), lytic lesion with irregular sclerosis and dilation (1/7), soft mass(7/7), speculate calcification(2/7), periosteal reaction(0/10); On MRI(n=10), T1WI showed isointensity(9/10) and slightly hyperintensity(1/10), T2WI and STIR images showed heterogeneous hyperintensity (8/10), uniform hyperintensity(2/10), soft tissue mass(10/10), the size ranged from 2.5cm×4cm to 7.5cm×13.5cm. Conclusion: The clinical and radiologic features of ES and pPNETs were different, compared with pPNETs, the patients with ES were younger, the commoner locations were long tubular bones, radiography and CT showed periosteal reaction and matrix mineralization, MRI showed the similar intensity but with smaller soft tissue mass, these features were helpful in differential diagnosis if combining with pathology.
2006, Vol. 17 
