Background: Radiation-induced sarcoma (RIS) has a 10-year incidence of 0.2-0.27% and a poor prognosis. In particular, radiation-induced fibrosarcoma has been rarer, and its incidence is 2.6-3.7% of RIS.
Case presentation: A 43-year-old woman with pT1N1M0 breast cancer underwent breast-conserving surgery, chemotherapy, radiation therapy eight years ago, and continued hormonal therapy. She complained of a hard mass palpated in her right axillary breast. Although we suspected local recurrence, core needle biopsy revealed atypical spindled tumor cells without mammary or epithelial markers. A diagnosis of fibrosarcoma was made via tumorectomy. She underwent additional enlarged surgery.
Conclusions: We report a rare case of fibrosarcoma after breast-conserving surgery and radiation therapy. Fibrosarcoma after radiation therapy for breast cancer has been reported in 30 cases, including the present case. The dead and alive cases were not significantly different in terms of age, primary breast cancer, radiation dose, and following months. Patients with breast masses after radiation therapy should be suspected local recurrence and RIS.