Metabolic Imaging of Advanced Basal Cell Carcinoma Treated with Sonidegib: A Retrospective Case Series Study.

Background : Positron emission tomography/computed tomography (PET/CT) with 18 F-fluorodeoxyglucose ( 18 F-FDG) is a firmly established tool in oncology and is gaining importance in dermato-oncology. However, its use in advanced basal cell carcinoma (BCC) is limited, with only a few case reports and a single study focused on vismodegib. This study evaluates the role of 18 F-FDG PET/CT in advanced BCC treated with sonidegib. Methods : We retrospectively assessed the clinical data of patients with advanced BCC who underwent 18 F-FDG PET/CT between January 2022 and January 2024. Inclusion criteria included histologically confirmed BCC, FDG-avid lesions on baseline PET/CT, and a minimum follow-up of 6 months. Metabolic response was assessed using the PET Response Criteria in Solid Tumors (PERCIST). Results : Four patients with advanced BCC treated with sonidegib were included, presenting with a total of 10 hypermetabolic lesions at baseline PET/CT. The mean interval between baseline and follow-up scans was 8.7 ± 1.6 months. According to PERCIST, two patients achieved a complete metabolic response (CMR), while the other two had stable metabolic disease (SMD). Low baseline-standardized uptake values (i.e., SUVmax, SUVmean) and reduced total lesion glycolysis (TLG) were associated with CMR. No relapses were observed during follow-up. Conclusions : This study suggests that 18 F-FDG PET/CT may help identify advanced BCC patients who are likely to benefit from sonidegib treatment. Further research is needed to fully explore the potential of PET/CT in this specific clinical context.