Granuloma-forming interstitial pneumonia induced by nivolumab: a possible immune-related adverse event of the lung.

Nivolumab, a monoclonal antibody targeting the PD-1, has recently been used as a standard treatment for lung cancer, melanoma and renal cell carcinoma. We herein report the case of a patient undergoing treatment for non-small cell lung cancer (NSCLC) who developed interstitial pneumonia which featured nivolumab-induced granuloma formation. An 82-year-old male patient with NSCLC was initially treated with radiation therapy and chemotherapy. Five years later, however, he developed metastatic carcinoma in a hilar lymph node accompanied by ground glass opacity (GGO), suggesting tumor cell invasion. Treatment with nivolumab was initiated. At 21 days after the first dose of nivolumab, he complained of cough and dyspnea. Chest computed tomography scans demonstrated tumor progression and newly formed GGO in the area surrounding the primary tumor. Fibrosing active alveolitis with granuloma formation and organizing pneumonia findings were observed in the pathological examination of a transbronchial lung biopsy (TBLB) specimen. No malignant cells were found in TBLB. A bacteriological analysis of cultures, a PCR, and special staining did not reveal any infections. The patient's pneumonitis improved after treatment with systemic corticosteroids. Granuloma-forming interstitial pneumonia may be a feature of nivolumab-associated pneumonitis.