Primary Ewing sarcoma of the breast in a male adolescent: A case report

Introduction: Ewing sarcoma predominantly affects children and adolescents. Breast Ewing sarcoma is exceptionally uncommon, with only 16 documented cases globally, just one being pediatric. Case presentation: A 14-year-old male was referred by a pediatrician for evaluation of a rapidly growing right breast mass over the course of 2 months. Diagnosis was confirmed via tumor tissue biopsy, immunohistochemistry (CD99+, NKX2.2+), and fluorescent in situ hybridization, which showed an EWSR1 break-apart on chromosome 22q12. Initial contrast-enhanced computed tomography of the chest revealed a huge tumor on the right breast with 2nd to 6th anterior rib involvement measuring 16.8x18.1x9.5 cm, and prominent right axillary lymph nodes. No distant metastasis was seen on positron emission tomography during metastatic work-up. The patient received neoadjuvant chemotherapy using vincristine, doxorubicin, and cyclophosphamide alternating with ifosfamide and etoposide over 12 weeks. The tumor size decreased significantly post-neoadjuvant chemotherapy, now measuring 3.9x12.2x6.5cm. After reassessment, the patient underwent wide excision of the right chest mass, en-bloc anterior 5th rib resection, right axillary lymph node dissection, with latissimus dorsi flap reconstruction with an uneventful perioperative course. He remained recurrence-free at the six-month follow-up. Conclusion: Although rare, Ewing sarcoma must be included in the differential diagnosis of rapidly growing breast masses in male adolescents.