Ipilimumab-Induced Immunomediated Adverse Events Possible Pitfalls in 18F-FDG PET/CT Interpretation

A 42-year-old woman underwent resection of a high-risk melanoma of the right thigh. Adjuvant treatment with ipilimumab was then started within a phase III randomised, double-blind clinical trial. F-18-FDG PET/CT scan showed intense uptake in mediastinal hilar lymph nodes, bilaterally, and in rectus abdominis muscle. Biopsy at the abdominal wall revealed a chronic granulomatous inflammation. After oral steroid treatment, all the areas of abnormal tracer uptake disappeared. Ipilimumab can induce inflammatory immunomediated reactions that should be taken into account to avoid misinterpretation.