What is a kidney cyst? What are the types of kidney cysts? Kidney cyst is a cystic lesion on the surface or inside of the kidney that does not communicate with the outside world. According to the causes, there are two types of renal cysts: congenital and acquired. Congenital, also known as hereditary renal cysts, commonly include polycystic kidney, medullary sponge kidney and polycystic renal dysplasia. Acquired ones are simple renal cysts, parapelvic cysts and acquired cystic nephropathy, the latter is mostly seen in uremia and long-term dialysis patients. Simple renal cysts are the most common in the clinic. What causes renal cysts? The causes of congenital renal cysts are as follows: 1. Congenital dysplasia. Congenital dysplasia can produce a variety of diseases, the common ones are medullary sponge kidney, dysplastic polycystic kidney disease and so on. The gene of congenital dysplasia is usually not abnormal, so it is different from genetic inheritance or genetic mutation; 2. Hereditary factors. Commonly, there are polycystic kidneys, most of which are inherited through parental genes, which are divided into autosomal dominant inheritance and autosomal recessive inheritance, but there are also patients with polycystic kidneys who are neither inherited from their parents nor belong to the congenital dysplastic polycystic kidney disease but are the genetic mutations during the formation of the embryo. Such cases are more rare. Therefore, some patients with polycystic kidney can have no parental genetic history; 3. Various infections. Infections can cause abnormal changes in the body’s internal environment thus producing environmental conditions favorable to changes in cyst genes, which increase the activity of internal factors of cysts, and this can promote the generation and growth of cysts. The formation of acquired renal cysts is relatively simple, mainly due to the obstruction of renal tubules, local ischemia and congenital developmental disorders. Due to the obstruction of renal tubules, localized expansion forms simple renal cysts. What is the danger of renal cysts to human body? Smaller renal cysts cannot be felt by the human body when they are normal. Larger cysts (more than 5cm in diameter) will compress normal renal tissues, resulting in damage to renal function, requiring laparoscopic decortication surgery or puncture and aspiration of cystic fluid. There is also a part of cysts located next to the renal pelvis, which will cause fluid retention in the patient’s kidneys, resulting in back pain, lumbar distension and other uncomfortable feelings. When kidney cysts become infected, bleed, or rupture under external force, they will cause patients’ low back pain and jeopardize their health. So you need to pay attention to kidney cysts, especially the larger ones, and need to go to the hospital for regular review. What are the symptoms of kidney cyst? A simple kidney cyst usually has no symptoms. However, when the cysts are large, they may cause the following symptoms 1. Lumbar and abdominal discomfort or pain: the pain is characterized by vague pain, dull pain, fixed on one side or both sides, radiating to the lower part of the body and the back of the waist. If the cyst is combined with infection and bleeding, the patient will feel severe pain, and at the same time there is an increase in body temperature; 2, hematuria: it can be manifested as microscopic hematuria or carnal hematuria; 3, abdominal mass: sometimes the main reason for the patient’s visit to the clinic, 60~80% can touch the enlarged kidney, the larger the kidney, the worse the renal function; 4, proteinuria: generally not much, not more than 2 grams of urine in 24 hours, so it will not occur nephrotic syndrome; 5, hypertension: usually not much, not more than 2 g of urine, so there will be no nephrosis Hypertension: cysts compress the kidneys, causing renal ischemia, which increases renin secretion and causes hypertension; 6, hydronephrosis. If the cyst is parapelvic cyst will cause hydronephrosis, causing the patient’s waist swelling and pain. What are the general methods to detect and follow up renal cysts? The following tests can be done to diagnose renal cysts: 1. Urine examination . Urine routine is generally normal, if the cyst compresses the renal parenchyma or combined with intracapsular infection, a small number of red blood cells and white blood cells can appear in the urine; 2, ultrasound . Can understand the number of cysts, size, cyst wall, and can be identified with renal mass, for renal cysts the preferred method of examination. Typical ultrasound performance for the lesion area without echo, smooth cyst wall, clear boundary. When the cyst wall shows irregular echoes or limited echo enhancement, malignant changes should be guarded against. When secondary infection, the wall of the cyst is thickened, the lesion area has fine echoes, and the echoes are enhanced when there is hemorrhage in the cyst. When the imaging suggests that there are multiple cysts, it should be distinguished from polycystic cysts and polycystic kidneys; 3. Intravenous urography (IVU). It can show the degree of cyst compression of renal parenchyma, and can be distinguished from hydronephrosis; 4, renal CT examination. Valuable for those who cannot be identified by ultrasound. When cysts are accompanied by hemorrhage, infection, or malignancy, they show inhomogeneity and increased CT value. When CT shows the characteristics of cyst, cyst puncture can be unnecessary. To identify cysts and hydronephrosis, CT urography (CTU) can be done; 5. Magnetic resonance imaging (MRI). If you need to further check the nature of the cyst, you can also perform MRI enhanced examination of both kidneys.