Radiation recall pneumonitis induced by nivolumab in a patient with renal cell carcinoma

A radiation recall reaction in previously irradiated lungs is known as radiation recall pneumonitis. We encountered a rare case of radiation recall pneumonitis induced by nivolumab 9 months after palliative radiotherapy to the ribs. Case presentation The patient was a 69‐year‐old woman with renal cell carcinoma. She had received various drugs and palliative irradiation, which was followed by nivolumab treatment, for renal cell carcinoma. Three days after the initial nivolumab administration, she presented with respiratory symptoms. On the basis of chest computed tomography findings, she was diagnosed with nivolumab‐induced radiation recall pneumonitis and treated with prednisolone (1 mg/kg). The condition resolved rapidly, and chest computed tomography 4 months after nivolumab cessation revealed interval resolution of the lung consolidation and persistent tumor shrinkage. Conclusion Physicians should consider the risk of radiation recall pneumonitis during treatment with immune checkpoint inhibitors in patients who have received previous thoracic radiotherapy.