For hyperechoic kidneys, the most likely cause is a tumor, and another possibility is a complex cyst. The incidence of renal tumors is actually low. The most common benign renal tumor in adults is renal malformation tumor, the technical term for this is called renal vascular smooth muscle lipoma. This is the most common benign tumor in adults, and it is mostly hyperechoic on ultrasound. However, the literature reports that about 20-30% of malignant tumors do not appear hyperechoic and appear hypoechoic or isoechoic. The most common malignancy in adults is renal cell carcinoma, also known as nephrocalcinoma, which mostly presents as hypoechoic. It has also been reported in the literature that 20%-30% of kidney cancers will exhibit hyperechoic echogenicity similar to that of malignant tumors. So there is an overlap of 20%-30% between benign and malignant tumors. In this case, if only plain ultrasonography is not enough, ultrasonography or enhanced CT is needed to assist in the diagnosis. In addition, complex cysts, that is, cysts with combined bleeding or infection, may also appear hypoechoic. In this case, to identify it clearly, further enhanced imaging is also needed, among which ultrasonography or enhanced CT is best.