Abstract
BACKGROUND: Imaging with 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) and (11)C-methionine (MET)-PET can delineate primary and metastatic brain tumors. Lesion size affects the sensitivity of both scans and histopathological features can also influence FDG-PET, but the effects on MET-PET have not been elucidated. CASE DESCRIPTION: We report an unusual case of metastatic brain tumors without accumulation of FDG or MET, contrasting with high FDG uptake in the primary lung lesion. The brain lesions were identified as adenocarcinoma with a more mucus-rich background, contributing to the indistinct accumulation of both FDG and MET. CONCLUSION: Histopathological characteristics can affect both MET and FDG accumulation, leading to findings contradicting those of the primary lesion.