A bone tumor‐like chest wall mass lesion with pathological rib fractures observed 13 years after lung stereotactic body radiotherapy: A case report

Abstract Although stereotactic body radiotherapy (SBRT) is a curative treatment option for stage I non‐small cell lung cancer (NSCLC), limited data are available regarding chest wall (CW) toxicities during an extended follow‐up of over 10 years. We report an unusual case of a bone tumor‐like CW mass lesion with pathological rib fractures observed 13 years after SBRT for peripheral lung cancer. Despite the initial suspicion of radiation‐induced sarcoma, a subsequent incisional biopsy revealed no evidence of malignancy, and a definitive diagnosis of osteonecrosis was made. Thus, long‐term observation of over 10 years is required to identify late chronic complications following SBRT.