A 44-year-old woman with a history of colon cancer underwent an F-18 fluorodeoxyglucose positron emission tomography (FDG PET) scan to evaluate for recurrence. Intense focal FDG uptake in the caudate lobe was noted, which corresponded to a 1.5-cm lesion on computed tomography. The patient was thought to have a solitary liver metastasis and underwent partial hepatectomy. The FDG-avid lesion was diagnosed as reactive lymphoid hyperplasia of the liver. Although it is a rare lesion, reactive lymphoid hyperplasia of the liver is an important source of false-positive results on FDG PET because it has been associated with carcinomas, in particular colon carcinoma.