Radiation-Induced Pleomorphic Dermal Sarcoma of the Chest Wall 25 Years After Breast Cancer Radiotherapy: A Case Report and Literature Review.

Radiation-induced sarcoma (RIS) is a rare but aggressive long-term complication of radiotherapy. It typically develops within previously irradiated tissues after a prolonged latency period and is associated with poor prognosis because of its locally invasive behavior and high recurrence rates. Breast cancer survivors who receive adjuvant radiotherapy remain at risk for secondary malignancies, including sarcomas arising within the radiation field. We report the case of a 78-year-old woman who developed a progressively enlarging chest wall mass 25 years after mastectomy and adjuvant radiotherapy for breast cancer. Initial clinical and radiological findings raised concern for local recurrence; however, histopathological examination with immunohistochemistry confirmed a high-grade pleomorphic dermal sarcoma arising within the previously irradiated field. The patient initially received gemcitabine and docetaxel chemotherapy, but follow-up fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) demonstrated disease progression. She subsequently underwent extensive chest wall resection with pulmonary resection and prosthetic reconstruction, followed by palliative radiotherapy for metastatic disease. This case highlights the importance of maintaining a high index of suspicion for RIS in patients presenting with new lesions decades after radiotherapy, as early biopsy with histopathological and immunohistochemical evaluation is essential for accurate diagnosis and appropriate management.