Out of 58 MM patients treated with anti-PD-1 or anti-CTLA-4 ICI, 20 irAE of interest (colitis, pneumonitis, and thyroiditis) were observed on 18F-FDG PET/CT scans in 18 (31%) patients: the bowel N=6 (11%), lung N=5 (9%), and thyroid N=9 (16%). Here, CTLA4 is linked to Miyoshi myopathy.