Ewing sarcoma; clavicle; chemotherapy; cancer in infants
Ewing sarcoma is the second most common childhood bone cancer [1]. Any bone can be affected, but it occurs more often in the femur and pelvis. Numerous series have been published, with the age at diagnosis ranging from 5 months to 83 years, most commonly 10-15 years. There is a 3:2 male predominance, and 95% of Ewing sarcomas occur in white patients [2,3]. Our experience with a Vietnamese female with Ewing sarcoma of the right clavicle is of interest given the patient's age and race and location of the tumor. S.N. presented at 10 months of age with a palpable mass over the right clavicle noted by her parents 1 month prior to presentation. Physical examination revealed a 4 Γ 3 cm palpable mass over the middle section of the right clavicle that was nontender to palpation. It was firm and fixed to the underlying bone. No sign of infection was noted. The patient had full shoulder range of motion (ROM), with normal strength and sensation in the right upper extremity.
Laboratory investigation revealed a white blood cell count of 11.6 K/l. Plain radiographs demonstrated a lesion in the diaphysis of the clavicle extending to within 1 cm of the acromial and sternal ends. There was a sunburst appearance to the lesion, with extensive periosteal reaction (Fig. 1). A bone scan showed increased uptake in the diaphysis of the right clavicle but no other areas of abnormal uptake in the skeleton. Magnetic resonance imaging (MRI) documented a soft tissue mass surrounding the right clavicle as well as marrow involvement by the lesion involving nearly the entire clavicle.
The differential diagnosis included Ewing sarcoma and osteosarcoma. A needle biopsy revealed small round blue cells consistent with Ewing sarcoma. Plain chest radiographs and a chest computed tomography (CT) scan were negative for metastases. A bone marrow examination was normal.
The patient was treated with chemotherapy comprising vincristine (2 mg/M 2 ), doxarubicin (40 mg/M 2 over 24 hr), and cyclophosphamide (10 mg/kg/day for 3 days). She received a total of three courses over 4 months, and the mass clinically decreased in size by 70%. The patient