Potential false-positive FDG PET imaging caused by subcutaneous radiotracer infiltration.

Whole-body fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) scanning has been useful in the management of a variety of malignancies with high accuracy. However, numerous nonmalignant lesions can also result in increased FDG accumulation and consequently may cause potential false-positive interpretation if the causes are not recognized. A single focus of FDG accumulation in the axilla can often easily be attributed to tracer infiltration when the injection was on the same side. However, multiple foci of FDG uptake can be similar to malignant lesions. A case is presented in which the follow-up study clarified the nature of multifocal increased FDG uptake in the axilla.