Marginal zone lymphoma (MZL) is usually considered not avid for FDG. We report a case of a 57-year-old man with an MZL suspected for transformation. FDG-PET/CT showed a diffuse atypical involvement of subcutaneous fat, without sign suggestive for a transformation. No cutaneous involvement was clinically evident. A random subcutaneous biopsy was performed and showed the presence of MZL.