1.Renal cysts: Typical renal cysts are easily distinguished from renal cancer from imaging examination, but when there is bleeding or infection inside the cyst, they are often easily misdiagnosed as tumors. And some renal clear cell carcinomas are internally homogeneous and very weakly hypoechoic, which are easily misdiagnosed as renal cysts during physical examination screening. For benign renal cysts with irregular wall thickening and high central density, it is difficult to identify them by applying any of the above examination methods alone, and often requires comprehensive analysis and judgment, and if necessary, puncture biopsy is feasible. Renal misshapen tumor: also known as renal vascular smooth muscle lipoma, is a relatively common benign tumor of kidney, which has characteristic performance on ultrasound and CT images, and can be easily distinguished from renal cell carcinoma clinically. The typical malignant tumor shows a moderately strong echogenic area in the mass on ultrasound due to the presence of fatty components, and the CT shows an area with negative CT value in the mass, which remains negative after enhancement scan. The CT value increased after enhancement scan, but it was not as obvious as normal kidney tissue. Angiography showed that the kidney itself was vasoconstricted after epinephrine injection, but the tumor vasculature was not, and the tumor vascular characteristics were more obvious. However, sometimes atypical renal malformation tumors with little fatty component are encountered, and it is difficult to distinguish them from renal cancer in this case. In addition, nuclear magnetic scan is also a good method to diagnose malignant tumor. In clinical practice, it is often necessary to combine ultrasound, CT and MRI scans to make a clear diagnosis for malignant tumors with little fat content. 3. Renal lymphoma: Renal lymphoma is rare but not uncommon. Lymphoma of the kidney lacks imaging features and presents as multiple nodular or diffusely moistened kidneys, increasing the kidney’s shape and involving more retroperitoneal lymph nodes. 4.Yellow granuloma of the kidney: It is a rare special type of severe chronic renal parenchymal infection with two morphological manifestations: one is diffuse, with enlarged kidney volume, morphological disorder and disorganized internal structure, which is not easily confused with tumor; the other is focal, with limited substantial nodular echogenicity in the kidney, which lacks specificity and is sometimes difficult to distinguish from tumor, but this part of patients usually have infection However, these patients usually have symptoms of infection, painful masses in the kidney area, and a large number of white blood cells or pus cells in the urine, so the differential diagnosis is not difficult with careful observation. 5.Inflammatory pseudotumor of kidney: The clinical manifestations of this disease are mainly lumbar pain, low fever and hematuria, and sometimes a mass can be found in the lumbar region, or it can be found during physical examination without any symptoms. It is less common clinically, and the correct diagnosis rate of IVP, ultrasound, CT and other imaging examinations is low. The following conditions are worth noting: the mass has irregular border, incomplete envelope and irregular morphology; there are inflammatory images around the mass and adjacent kidney or there are hematomas and effusions around the kidney, suggesting the possibility of non-malignant tumor. For those who are suspected to have inflammatory pseudotumor of kidney, urine culture should be routinely done, antibiotic treatment can be tried, and changes in condition can be observed, and surgery can be avoided for those whose symptoms improve. For those who cannot avoid surgery, preoperative multi-point renal aspiration biopsy should be performed under ultrasound guidance as much as possible. Intraoperatively, a rapid frozen pathological section should be performed before deciding whether to perform nephrectomy, which is the basis for the final clear diagnosis to avoid unnecessary nephrectomy.