Renal cyst is a general term for the presence of cystic masses of varying sizes in the kidney that do not communicate with the outside world. Common renal cysts can be divided into adult-type polycystic kidney, simple renal cysts and acquired renal cysts. Symptoms: Most renal cysts are asymptomatic. Physical examination is mostly normal, and occasionally a mass can be palpated or percussed in the kidney area. If the cyst becomes infected, there may be pressure pain in the 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 waist 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 tip, 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 occur. 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, and the enlarged kidney can be palpated in 60% to 80% of patients. 4.Proteinuria: usually the amount is not much, not more than 2g in 24 hours urine. mostly nephrotic syndrome will not occur. 5.Hypertension: due to the cyst compressing the kidney, it causes 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. Examination and diagnosis of urine analysis is mostly normal. Microscopic hematuria is rare. Renal function tests are also normal, unless the cyst is multiple or bilateral (rare). Even if there is extensive destruction of the surface of one kidney, the contralateral kidney may maintain normal total renal function due to compensatory hypertrophy. x-ray examination often shows a part of the kidney shadow that is enlarged or a mass compressed on it in abdominal plain radiographs. Sometimes streaks of calcification can be seen at the edges of the mass. The diagnosis is confirmed by excretory urography, which shows an increased density of blood vessels in the renal parenchyma on a film taken 1 to 2 minutes after the intravenous push of contrast, but not in the part of the space occupied by the cyst, because there are no blood vessels in it. Serial urographic views show the presence of a mass. The cyst is often surrounded by one or several calyces or pelvises that become widened, flattened or even the lumen disappears due to depression or curvature. ct scan is the most accurate in identifying renal cysts from tumors. The density of cystic fluid approximates water, while the density of tumor is similar to that of normal kidney parenchyma. After intravenous contrast injection, the renal parenchyma becomes denser while the cyst remains unaffected; the cyst wall is clearly demarcated from the renal parenchyma while the tumor is not; the cyst wall is thin while the tumor is not. In many ways, differentiating between cysts and tumors CT is superior to puncture aspiration judgment. Renal ultrasonography accounts for a large proportion of the non-invasive diagnostic techniques taken to identify renal cysts and parenchymal masses. Diagnostic points 1. The disease is usually asymptomatic in the early stage and is often detected during physical examination ultrasound. 2.Cystic masses can occasionally be found in the lumbar abdomen during physical examination. 3.B ultrasound can often make a clear diagnosis, and further examination can be used when malignant changes are suspected as listed. Simple renal cyst treatment is the most common among renal cystic diseases. They are mostly unilateral and single, rarely unilateral and multiple, and bilateral occurrence is rare. When the cyst is small (<4cm in diameter), it can be left untreated for the time being and observed regularly. When the cyst is >4cm, ultrasound-guided puncture and drainage or sclerotherapy can be considered. Laparoscopic cystectomy can be considered for huge cysts >8 cm.