|Patient: 6 year old male|
|History: 6 year old boy with a history of Stage IV-S neuroblastoma. He has been disease free for approximately 5 years. Presented in March with a chest wall lump - biopsy diagnostic for Ewing's sarcoma.|
|Diagnosis: Ewing Sarcoma|
|Discussion: Ewing sarcoma is a highly malignant primary bone tumor. The tumor is derived from red bone marrow. Most frequently, it is observed in children and adolescents aged 4-15 years and rarely develops in adults older than 30 years. Ewing sarcoma accounts for approximately 5% of biopsy-analyzed bone tumors and approximately one third of primary bone tumors. Ewing sarcoma is the second most common malignant bone tumor in young patients, and it is the most lethal bone tumor. Males are affected more frequently than females, with a ratio of approximately 1.5:1. Ewing sarcoma occurs in African Americans and Asians. An association exists between Ewing sarcoma and primitive peripheral neuroectodermal tumor. |
Most frequently, the tumor is diagnosed as a monostotic lesion in the metaphysis or diaphysis of the long bones of the extremities. The tumor also may occur, although less frequently, in the pelvic area, ribs, and scapulae. In fact, any bone may be involved. Typically, the periosteal reaction and new bone formation with an onionskin appearance may suggest the diagnosis of Ewing sarcoma. The radiographic appearance of Ewing sarcoma may vary highly from a lytic one to a dominantly sclerotic one.
The most important and earliest symptom is pain, which initially is intermittent but becomes intense. The pain may radiate to the limbs, particularly with tumors in the vertebral or pelvic region. Neurologic signs such as nerve root signs and cord compression are present in one half of patients with involvement of the axial skeleton. Rarely, a patient may have a pathologic fracture. Occasionally, the clinical picture may be similar to that of acute or chronic osteomyelitis and include remittent fever, mild anemia, leukocytosis, and an elevated sedimentation rate. Increased serum lactic dehydrogenase levels and weight loss also may be observed. Symptoms usually last a few weeks to a few months. Eventually, most patients have a large palpable mass, which rapidly grows, with a tense and tender local swelling.
No single morphologic or functional imaging method provides findings for a specific diagnosis of Ewing sarcoma, but the results do contribute to tumor staging. Therefore, obtaining a histologic specimen of the lesion in all patients is essential in planning therapy. Because the clinical symptoms are nonspecific and because they frequently suggest osteomyelitis, an initial conventional radiographic and/or MRI examination is performed. These may reveal the classic signs of Ewing sarcoma. Although plain radiographs may show typical signs of Ewing sarcoma, MRI provides more accurate information about tumor size. MRI is superior to CT in delineating the extent of the neoplasms and their relation to the surrounding structures.
Both long and flat bones are affected because no bone is immune to tumor development. In the long bones, the tumor is almost always metaphyseal or diaphyseal. Most commonly, radiographs show a long, permeative lytic lesion in the metadiaphysis and diaphysis of the bone with a prominent soft tissue mass extending from the bone.
Sclerotic lesions are less common but may occur in approximately 25% of cases. Plain radiographs of the long bones may show a lesion with poorly defined margins that is destroying the bone. The lesion may invade the cortical bone, although Ewing sarcoma may also traverse the Haversian system and cause a large soft-tissue mass outside the bone despite the absence of cortical destruction. This phenomenon is noted in approximately one half of patients with Ewing sarcoma. A periosteal reaction usually is present, and it often has an onionskin or sunburst pattern, which indicates an aggressive process. In some patients, Codman triangles may be present at the margins of the lesion. These result from the elevation of the periosteum and central destruction of the periosteal reaction caused by the tumor. In rare cases, a lesion is not visible on plain radiographs.
CT helps in defining bone destruction. Tumor size can be evaluated with contrast-enhanced CT, which may be used in follow-up evaluation during chemotherapy. However, the preferred method in staging and following up Ewing sarcoma still is MRI.
MRI is essential to elucidate soft-tissue involvement because the tumor has low signal intensity on T1-weighted images compared with the normal high signal intensity of the bone marrow. On T2-weighted images, the tumor is hyperintense compared with muscle. After treatment, osteosarcomas and Ewing sarcomas may have the reduced signal intensity of bone marrow, which may be isointense with muscle. They may also have a well-defined margin. However, the changes in signal intensity reflect changes in the bone marrow structure and nonspecific changes such as fibrosis. The change in signal intensity is helpful in noting a therapeutic effect, but it sometimes causes difficulties in detecting residual tumor tissue.
Treatment of Ewing sarcoma has evolved so that patients can now expect 60%–80% survival when presenting as a nonmetastatic, nonrecurrent disease. Management consists of two major components: systemic chemotherapy and local control. These two components are carried out in three phases: (1) induction chemotherapy, the goal of which is to achieve rapid initial cytoreduction and facilitate local control, (2) local control using surgery, radiation therapy, or both, usually after 10–12 weeks of induction chemotherapy, and (3) continuation therapy, which consists of chemotherapeutic regimens similar to those used for induction.
|References: Hoffer, FA. "Primary Skeletal Neoplasms: Osteosarcoma and Ewing Sarcoma." Topics in Magnetic Resonance Imaging. 2002 Aug; Vol. 13 (4), pp. 231-9.|
Kennedy, JG. "Ewing Sarcoma: Current Concepts in Diagnosis and Treatment." Current Opinion in Pediatrics. 2003 Feb; Vol. 15 (1), pp. 53-7.
Khoury, JD. "Ewing Sarcoma Family of Tumors." Advances in Anatomic Pathology. 2005 Jul; Vol. 12 (4), pp. 212-20.
Strauss, Ludwig G, MD. "Ewing Sarcoma." www.emedicine.com. February 16, 2007.
Andrew Knerl, Medical Student, Creighton University, Omaha, NE.
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Case Number: 4351760Last Updated: 03-27-2007 The reader is fully responsible for confirming the accuracy of this content.
The reader is fully responsible for confirming the accuracy of this content.