A highly aggressive small, round, undifferentiated, blue cell tumor that is often is metastatic at the time of diagnosis (15-30% of the time). They are frequently large (approximately 5 to 10 cm) at the time of clinical diagnosis.
Most commonly seen in young population, about 90% of cases are seen in patients between 5 and 30 years of age. A young Caucasian male with localized pain, swelling, fever, weight loss, anemia, and leukocytosis would be consistent with Ewing’s sarcoma.
The primary malignancy can occur in any bone but most commonly in the lower skeleton with the proximal metadiaphyseal femur and pelvis the most common sites. Malignant lesions commonly involve the spine and skull.
Radiographic features are typically aggressive. Poorly marginated bone destruction and soft tissue mass are the most common findings. Other aggressive features include periostitis (onion peel and hair-on-end patterns can be seen) and cortical erosion.
Radiographic evaluation is usually by conventional radiography, CT, MR, and Bone Scintigraphy (Technecium-labelled diphosphonates and Gallium).
Differential diagnosis after radiographic evaluation often includes osteosarcoma , lymphoma (typically older age group and absence of soft tissue mass), metastatic neuroblastoma (typically younger age group), PNET (not distinguishable by Radiologic findings, must be differentiated histologically), and infection. Biopsy must then be performed.
Treatment can include chemotherapy, radiation therapy as well as surgery. Recurrence at the original site is relatively common. When metastases occur, the lungs and bones are commonly involved.
Reference(s): Orthopedic Radiology. Adam Greenspan, 3rd Ed., 2000, pp. 690-694.
Diagnosis of Bone and Joint Disorders. Donald Resnick and G. Niwayama, 2nd Ed., 1988, pp. 3845-3855.
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