Nivolumab-Associated Pulmonary and Bone Sarcoidosis in a Patient With Melanoma of Unknown Primary.

A 57-year-old man with stage IIIB malignant melanoma of unknown primary presented for pretherapy FDG PET/CT that demonstrated metastatic left cervical lymph node with no other site of involvement. Following left neck dissection, nivolumab was initiated. Follow-up FDG PET/CT 3 months after initiation of nivolumab demonstrated extensive radiotracer-avid chest lymphadenopathy and multiple bone lesions. Ultrasound-guided endobronchial biopsy of the mediastinal lymph nodes demonstrated sarcoidosis.