Radiation-induced osteosarcoma of the chest wall after treatment for unresectable thymoma

Secondary osteosarcoma is a rare complication of radiation therapy for a primary tumor. Here we report a unique presentation of radiation-induced osteosarcoma of the chest wall after radiation treatment for thymoma. This patient underwent multiple imaging studies, including magnetic resonance imaging and computed tomography with cinematic rendering. Diagnosis of osteosarcoma was confirmed through imaging features and histology. Several surgical procedures were performed to evaluate and attempt resection of the tumor, but ultimately the tumor location and involvement prevented adequate resection and chemotherapy was initiated. This case highlights the importance of identifying clear cumulative dose thresholds for radiation therapy and rare complications of radiotherapy.