Melanoma Metastases to Palatine Tonsils Obscured by Physiological FDG Uptake on PET/CT

Melanoma metastases to tonsils are rare. Tonsil metastasis has a poor prognosis where tonsils do not have afferent lymphatics, so any metastasis to the tonsil suggests hematogenous dissemination. Positron emission tomography (PET) using F-18 fluoro-2-deoxy-glucose has gained wide acceptance in patients with malignant melanoma in particular in patients with clinical suspicion of systemic metastatic spread. We report a case with a history of a cutaneous melanoma in the right supraclavicular region 12 years ago who underwent PET/CT for follow-up. This case clarifies how a malignant process can occasionally escape detection by PET/CT when placed in a region with high physiological metabolic activity like the tonsils.