FDG PET or PET/CT in Evaluation of Renal Angiomyolipoma

Objective: Angiomyolipoma is the most common benign kidney tumor. However, literature describing FDG PET findings on renal angiomyolipoma (AML) is limited. This study reports the FDG PET and PET/CT findings of 21 cases of renal AML. Materials and Methods: The study reviews FDG PET and PET/CT images of 21 patients diagnosed with renal AML. The diagnosis is based on the classical appearance of an AML on CT scan with active surveillance for 6 months. The study is focused on the observation of clinical and radiographic features. Results: Six men and 15 women were included in our study. The mean age of the patients was 57.14 ${\pm}$ 9.67 years old. The mean diameter of 21 renal AML on CT scans was 1.76 ${\pm}$ 1.00 cm (Min: 0.6 cm; Max: 4.4 cm). CT scans illustrated renal masses typical of AMLs, and the corresponding FDG PET scans showed minimal FDG activities in the area of the tumors. None of the 21 AMLs showed a maximum standardized uptake value ($SUV_{max}$) greater than 1.98. No statistically significant correlation was present between $SUV_{max}$ and tumor size. Conclusion: Renal AMLs demonstrate very low to low uptake on FDG PET and PET/CT imaging in this study. When a fat-containing tumor in the kidney is found on a CT scan, it is critical to differentiate an AML from a malignant tumor including an RCC, liposarcoma, and Wilms tumor. This study suggests that FDG PET or PET/CT imaging is useful for differentiating a renal AML from a fat-containing malignant tumor.