The majority of renal cysts are asymptomatic. Physical examination is mostly normal, occasionally a mass can be palpated or percussed in the kidney area. If the cyst is infected, there may be pressure pain in the abdomen. If the cyst is large, a mass may appear in the lumbar abdomen. Some patients may have the following symptoms due to the cyst itself and the increased pressure inside the cyst, infection, etc.: 1. Discomfort or pain in the lumbar and abdomen: the cause is due to the enlargement and expansion of the kidney, which increases the tension of the kidney envelope and strains the kidney tissues, or causes pressure on the neighboring organs. In addition, polycystic kidneys cause the kidneys to contain a lot of water, become heavy, and drop and pull, which also cause pain in the lower back. The pain is characterized by vague and dull pain, fixed on one or both sides, radiating to the lower part and low back. If there is intracapsular hemorrhage or secondary infection, the pain will suddenly increase. If combined with stones or blood clots blocking the urinary tract after bleeding, renal colic may appear. 2.Hematuria: It can be manifested as microscopic hematuria or meatus hematuria. The attack is periodic. Back pain often increases during the attack, and can be triggered or aggravated by strenuous exercise, trauma and infection. The reason for bleeding is that there are many arteries under the wall of the capsule, and due to increased pressure or combined infection, the blood vessels of the capsule wall rupture and bleed due to excessive strain. 3, abdominal mass: Sometimes it is the main reason for patients to visit the clinic. 60% to 80% of patients can palpate the enlarged kidney. Generally speaking, the larger the kidney, the worse the kidney function. 4.Proteinuria: generally the amount is not much, not more than 2g in 24 hours urine. more will not occur nephrotic syndrome. 5.Hypertension: solid cyst compresses the kidney, causing renal ischemia, which increases renin secretion and causes hypertension. When the kidney function is normal, more than 50% of patients have hypertension, and the incidence of hypertension is higher when the kidney function is decreasing. 6.Decreased renal function: due to cyst occupancy and compression, normal renal tissue is significantly reduced and renal function is progressively decreased. Kidney cysts are generally divided into three categories: adult type kidney cyst is a congenital genetic disease, the kidney parenchyma is filled with several round cysts of different sizes that are not connected to the outside world, the cysts contain liquid, small ones are invisible to the naked eye, and large ones can be several centimeters, so it is called polycystic kidney. The symptoms are increased nocturia, back pain and high blood pressure. Urinalysis with hematuria and small amount of proteinuria often develops slowly into chronic renal failure. There are 10% of people with kidney stones and 30% of people with polycystic liver. Experienced doctors can confirm the diagnosis with the help of ultrasound and intravenous pyelogram. Simple renal cyst may be a congenital anomaly, which is unilateral or bilateral kidney and has one or several cystic cavities of varying sizes that are round and not connected to the outside world, mostly unilateral, so it is called simple renal cyst. Its incidence can increase with age, and 50% of people over 50 years old who do ultrasound can find such cysts. The diagnosis can be confirmed with the help of ultrasound and CT. The unique characteristics of simple renal cyst: Simple renal cyst is the most common kind of cystic kidney disease in clinic, unlike polycystic cyst, the disease is not inherited but formed later in life, in the past it was thought that it was caused by local ischemia, in recent years the study thought that it might be developed by renal tubular diverticulum. The incidence of simple renal cysts increases with age as the distal tubules and collections and diverticula increase. The incidence increases with age, mainly in adults, and about half of people over 50 years of age have at least one cyst. The cysts can be one-sided or two-sided, with one or a few cysts in each kidney. The cysts are usually isolated and spherical in shape and can change the shape of the kidney if located superficially in the renal cortex or can be located deep in the cortex or medulla, with a diameter of 0.5 to 1M or 3 to 8M. The cyst wall is thin and transparent and contains straw yellow fluid, which is more viscous. The cyst is not connected to the renal pelvis and the wall is lined with a single layer of flattened epithelial cells. The disease is usually asymptomatic and is often discovered inadvertently for other purposes or during physical examination. Occasionally, hematuria and localized pain, calyx obstruction and secondary infection may occur. Individuals develop hypertension due to compression of adjacent blood vessels by the cyst, resulting in local ischemia and increased renin, at which point aspiration of the cystic fluid or removal of the cyst is followed by a reduction in blood pressure to normal, occasionally leading to erythrocytosis. The disease does not lead to renal hypofunction. The natural changes in simple renal cysts are slow. Acquired renal cysts, which occur mainly as a result of uremia or after dialysis treatment. It is not related to age, but to the duration of hemodialysis. The kidney originally does not have renal cysts, and according to the literature, most patients who have been on dialysis for more than 3 years will develop cysts. It has at least 4 cysts in one kidney, mostly 2 to 3 centimeters in diameter. Some cysts can become infected or even cancerous, and B ultrasound or CT examination can confirm the diagnosis.