Angiomyolipoma is a benign tumor consisting of abnormal vessels, smooth muscles, and fatty tissue. Renal cell carcinoma is an insidious neoplasm accounting for approximately 2% of global cancer diagnoses. Due to similar diagnostic features, the differentiation between the two types is sometimes difficult. We hereby present the case of a 60-year-old patient with no clinical symptoms and a focal lesion in the parenchymal layer of the left kidney incidentally detected on ultrasound examination. The putative diagnosis was angiomyolipoma, which was then confirmed by another ultrasound and computed tomography examinations. However, a further radiologic consultation revealed another probable diagnosis – renal cell carcinoma. Contrast-enhanced ultrasound was conducted, and the enhancement pattern was suggestive of cancer. To sum up, a thorough imaging examination plays an important role in the diagnostic work-up of neoplastic lesions in the kidney. Even then, however, the radiological image of the lesion may be misleading, so differential diagnosis is important for making a proper diagnosis.