Erythema Nodosum-Like Panniculitis as a False-Positive 18F-FDG PET/CT in Advanced Melanoma Treated With Dabrafenib and Trametinib.

We present a 35-year-old woman with left axillary mass. Histopathological analysis revealed metastatic infiltration for BRAF-mutant melanoma. F-FDG PET/CT showed bilateral axillary lymphadenopathy as well as bone and subcutaneous metastases. Dabrafenib (a BRAF inhibitor) and trametinib (a MEK inhibitor) combined therapy was started with a complete metabolic response established by 2 consecutive PET/CT scans. A follow-up PET/CT showed FDG uptake in several subcutaneous nodules in both distal legs, suggesting metastases. Painless cutaneous lesions were observed on physical examination, and biopsy revealed erythema nodosum-like panniculitis.