Temporal Increase in FDG Uptake in Renal Oncocytoma on Serial FDG PET/CT

Renal oncocytoma is a benign tumor characterized by eosinophilic granular cytoplasm reflecting abundant mitochondria. Although it is benign, it is often difficult to differentiate from malignant tumors, particularly renal cell carcinoma. In this case report, we present a pathologically confirmed case of renal oncocytoma demonstrating a temporal increase in FDG uptake. An 80-year-old woman underwent bilateral mastectomy and chemotherapy for breast cancer and was subsequently followed with serial respiratory-gated 18 F-fluorodeoxyglucose (FDG) PET/CT examinations. The most recent FDG PET/CT demonstrated a 2.2-cm renal nodule with intense FDG uptake. Thus, this case further illustrates the dynamic metabolic behavior of this benign tumor.