Ewing sarcoma is a malignant, small round cell bone tumor, presenting predominantly in children and adolescents. Ewing sarcoma may develop in every bone; diaphyses of long bones, ribs and flat bones are the main locations. Local and systemic clinical symptoms are nonspecific - pain, swelling, fever or ill-being.
The aim of the study was to assess the role of radiography, computed tomography and magnetic resonance imaging in the analysis of bone lesions in children and young adults with Ewing sarcoma.
Twenty-seven patients, aged between 1 year and 10 months, and 17 years and 2 months, with histologically verified Ewing sarcoma of the bone, referred to the Radiological Department of University Hospital No 6., John Paul II Upper Silesian Centre for Child Health Katowice, in the period from 1996 to 2007, were included in the study.Plain radiography was performed in every child, CT in 20 and MRI in 12 individuals. Tumour location, extension of the tumour, soft tissue mass, and periosteal reaction were taken into consideration in the evaluation of the lesion. In some cases, pathological features of the MRI and CT were compared. The prevalence of some radiological features was compared to the literature data.
The most common site of tumor was: ribs (6 children), femoral bone (6 children), pelvis (4 children) and tibia (3 children). In 2 children, a primary tumor was diagnosed in the spine (multifocal in 1 child).
X-rays revealed: periosteal reaction in 17 children (63%), soft tissue involvement in 19 children (70%), permeative component in 16 children (59%), and sclerotic component in 5 children (19%). In 10 children (37%), periosteal reaction was not detected. The examination revealed: soft tissue calcifications in 7 cases (26%), a well-delineated focus of destruction within bones in 3 children (11%), cortical thickening in 4 children (15%), cortical destruction in 4 children (15%), saucerisation in 3 children (11%), bone expansion in 3 children (11%), pathological fracture in 2 children (7%), cystic component in 1 child (4%), and vertebra plana in 1 child (4%).Reaction of tumors after i.v. contrast administration, shown on CT, was visible in 16 children – it was useful for a better description of the tumor and extension of the mass within the soft tissue. All MRI examinations (12 children) showed a heterogenous mass with ill-defined borders and a violated cortex. Low signal intensity of the tumor in a T1-weighted image and high signal intensity in a T2-weighted image was shown as well.
Heterogenous enhancement of signal intensity on T1-weighted images could be observed after i.v. contrast administration.
MRI examinations showed: tumor in an adjacent soft tissue in 11 children, and involvement of the epiphyseal plate or of the joint cavity in 6 children.
X-ray and MRI are essential in diagnostics. CT examination is more useful to estimate periosteal reactions and destruction of bone and marrow cavity, especially in flat bones. However, to recognise a malignancy, it is necessary to perform a histopathological examination. In doubtful cases, the examination has to be verified as well.