Radiation-induced angiosarcoma-An unusual cause of recurrent pleural effusion.

Although rare, radiotherapy can induce secondary malignancies, such as radiation-induced angiosarcoma (RIAS), which is associated with a poor prognosis. Early detection is crucial for improving outcomes. The modified Cahan criteria are instrumental in diagnosing RIAS, which is ultimately confirmed through histological examination. We present a case of a middle-aged woman who developed RIAS after undergoing radiotherapy post-surgery and adjuvant chemotherapy for right-sided breast cancer. The patient presented with a rapidly reaccumulating right-sided pleural effusion, and RIAS was confirmed through pleural biopsy and aspirate. This case report highlights the pathway for establishing a diagnosis of RIAS and the need for early detection through clinical examination and surveillance imaging for patients following radiotherapy.