DISCUSSION
The radiograph revealed a residual root from the wisdom tooth. Also visible was a large radiolucency with diffuse noncorticated borders located in the ramus of the mandible just proximal to the area of the impacted third molar. The remainder of the tooth was removed, and a simultaneous biopsy of what appeared to be a solid mass lesion was performed. Pathologic examination yielded a diagnosis of Ewing's sarcoma. A thorough evaluation determined that there were no metastases; the cancer most likely represented a second primary lesion, not metastatic disease from the previous leg sarcoma.
Ewing's sarcoma is the third most common bone tumor (incidence of 10%-15%) next to osteosarcoma (45%) and chondrosarcoma (20%-25%).1 Approximately 225 new cases of Ewing's sarcoma are diagnosed each year in North America.2 The tumor usually occurs during the second and third decade of life and has a slight predilection for men. Whites are more frequently affected than Asians or blacks.3
The Ewing's sarcoma family of tumors includes Ewing's sarcoma of the bone, extraosseus Ewing's sarcoma, primitive neuroectodermal tumors (PNETs), and Askin tumors (PNETs of the chest wall).3 These tumors are often referred to as small round blue cell tumors because by light microscopy, they consist of small round cells that contain regular round nuclei, which stain blue and occupy almost the entire cell; a scant amount of cytoplasm; and tightly packed chromatin.1 The classic cytogenetic abnormality associated with Ewing's sarcoma as well as with other PNETs is the reciprocal translocation between chromosomes 11 and 22.1 Identification of this chromosomal rearrangement is valuable in distinguishing Ewing's sarcoma from other small round cell tumors.3
Ewing's sarcoma tends to occur in the diaphyses of long bones as well as in the flat bones of the body, but any bone may be affected. The most common sites are the lower extremity (45%), pelvis (20%), upper extremity (13%), axial skeleton and ribs (13%), and face (2%).3
The presenting complaint is usually local bone pain, tenderness, and a palpable mass. As with this case, pain may also be accompanied by paresthesias. The duration of symptoms prior to a definitive diagnosis can be weeks to months, with a median interval of 3 to 9 months.2 Often when adolescents present with bone pain, the symptoms are attributed to growth spurts or minor sports injuries, which can add to delay of a definitive diagnosis.2
No currently available blood, serum, or urine test can specifically identify Ewing's sarcoma. However, nonspecific signs of inflammation may be noted, such as elevated ESR, moderate anemia, or leukocytosis. An elevated lactate dehydrogenase level correlates with severity of the tumor.2 On plain radiographs, the lesion appears radiolucent and lytic, classically causing layered periosteal calcifications, or socalled onion skinning.1 When reviewing radiographic films, the PA should focus not only on the area of concern but also look at the entire film. The tendency is to gravitate toward the injured area, but as this case demonstrates, unexpected pathologies may be found. In this case, the area of radiolucency in the ramus of the mandible was visible in the panoramic radiograph and, on closer review, can also be seen on the initial cervical spine film (see Figure 2). MRI best defines the extent of the lesion. As with other sarcomas, biopsy is the definitive diagnostic test. Although the diagnosis can be made by fine needle aspiration or by core needle biopsy, the best means of sampling is by open biopsy.2 In addition to imaging the primary site of the lesion, chest radiography, CT of the chest, and bone scanning should be performed to evaluate for metastatic disease. Primary metastasis in lungs, bone, and bone marrow is detected in about 25% of patients.2
Treatment of Ewing's sarcoma is with multivalent chemotherapy, radiation, and surgical resection. Approximately two-thirds of patients survive diseasefree. The prognosis is poor in patients with a large tumor size, pelvic lesions, or presence of metastatic disease and in those who have a poor response to chemotherapy.2 Our patient underwent full surgical excision of his tumor and partial resection of the jaw bone followed by chemotherapy. Facial reconstruction using a vascularized fibula free flap was performed at the time of the initial surgery. Currently the patient is doing well and is disease-free. JAAPA
Denise Rizzolo is an assistant professor at the Seton Hall University PA program, South Orange, New Jersey, and works at the Care Station in Springfield, New Jersey. Andrea Medel is a student in the Seton Hall University PA program. Thomas Chiodo is an oral maxillofacial surgeon in Somerville, New Jersey, and a clinical assistant professor at the University of Medicine and Dentistry, New Jersey, Newark. The authors have indicated no relationships to disclose relating to the content of this article.
Julie Vajnar, PA-C, RT, department editor
REFERENCES
1. Patel SR, Benjamin RS. Soft tissue and bone sarcomas and bone metastases. In: Fauci AS, Braunwald E, Kasper DL, et al, eds. Harrison's Online. Based on: Harrison's Principles of Internal Medicine. 17th ed. New York, NY: McGraw-Hill; 2008. http://www.accessmedicine.com/content.aspx?aID=2866942. Accessed April 6, 2009.
2. Bernstein M, Kovar H, Paulussen M, et al. Ewing's sarcoma family of tumors: current management. Oncologist. 2006;11(5):503-519.
3. Burchill SA. Ewing's sarcoma: diagnostic, prognostic, and therapeutic implications of molecular abnormalities. J Clin Pathol. 2003;56(2):96-102.