Fluorine-18 fluorodeoxyglucose uptake in the retractile testis

A 51-year-old man with a palpable mass in his right inguinal region had fluorine-18 fluorodeoxyglucose (F-18 FDG) whole-body positron emission tomography (PET) in our cancer screening program. FDG accumulated in the mass, suggesting a metabolically active lesion that was likely malignant. A pelvic MRI and a urologist's palpation revealed that his inguinal mass was a retractile testis. Because a retractile testis is a benign process with no need for interventional therapy, it would be considered a false-positive finding on the cancer screening program using F-18 FDG PET.