What is renal malformation tumor? Renal malformation tumor is a benign tumor, also known as “smooth muscle angiolipoma” because it is composed of blood vessels, smooth muscle and fat. Larger malformation tumors may distort and displace the renal calyces in one or more places, affecting the drainage of urine, which may cause damage to the kidney function. In addition, because the tumor tissue is rich in blood vessels, it is prone to bleeding. Intratumor bleeding may cause severe pain, and if it ruptures toward the renal calyces, it can cause massive hematuria and endanger life. Some renal malformation tumors are very similar to renal cancer in morphological manifestations, so it is not easy to distinguish them, and surgical exploration is needed to make a clear diagnosis. Very few patients with renal malformation tumor may have tuberous sclerosis complex (TSC), which is an inherited familial disease. 80% of patients have butterfly sebaceous adenoma on the face, and other organs such as brain, eye, bone, heart and lung also have corresponding lesions. These patients have multiple diffuse tumors in both kidneys, with many large tumors that can easily affect kidney function, and require early and repeated surgical removal of kidney tumors to preserve normal kidney tissue as much as possible. Do I need to operate for renal malformation tumor? If the tumor is small and asymptomatic, it can be closely observed after ruling out the possibility of malignancy. However, because malignant tumors are rich in blood vessels and fragile, they may bleed easily, causing sudden and severe pain and hematuria, in which case emergency surgery is required to remove the bleeding tumor. Therefore, if the tumor is >100px in diameter, it can be surgically removed prophylactically. Malignant tumors with little fat content are difficult to differentiate from renal cancer and require surgical exploration for a definitive diagnosis. Patients with familially inherited renal malformation tumors require early surgery to preserve the renal unit, remove the tumor tissue, and protect the kidney function. What is epithelioid hemangiosmooth muscle lipoma? Epithelioid vascular smooth muscle lipoma is a rare subtype of vascular smooth muscle lipoma, accounting for approximately 1% of all vascular smooth muscle lipomas. Unlike common vascular smooth muscle lipoma, this tumor has vascular, smooth muscle and fat components as well as a proliferating epithelioid cell component. This particular component causes the malignant manifestation of the tumor, and the more the epithelioid cell component, the more aggressive the tumor is, and about 1/3 of them will develop lymph node or lung metastasis. Therefore, epithelioid vascular smooth muscle lipoma should be regarded as malignant tumor clinically, and there is a possibility of recurrence and metastasis after radical surgery, which should be followed up closely and should not be taken lightly.