Cystic kidney disease

　　First, the cause of the disease

　　The cause of polycystic kidney disease is gene deletion, with adult polycystic kidney often being caused by gene deletion on chromosome 16, occasionally by gene deletion on chromosome 4, which is an autosomal dominant inheritance with an penetrance of 100%. Therefore, a chromosomal deletion in one parent will give the child a 50% chance of inheriting the disease. Infantile polycystic kidney is an autosomal recessive inheritance, and both parents must have the gene mutation for their children to develop the disease, with an incidence rate of 25%.

　　Evidence of the disease's genetic relationship includes reports by Buck et al. of a family of 8 siblings, 6 of whom had renal cysts, and their father and uncle also died of uremia; the next generation had 5 people with kidney disease; Brasck et al. reported that polycystic kidney was found in 4 generations of a family; Reason et al. reported identical twins suffering from the disease; Crawford reported that 17 out of 40 people in a family had polycystic kidney.

　　The disease is 70% to 90% bilateral, in the 62 cases reported by Lejars, only 3 were unilateral; Oickinson reported that the ratio of unilateral to bilateral is 1:26. Gross examination shows that the volume of polycystic kidney is 2 to 3 times larger than that of a normal kidney. There have been reports of a bilateral polycystic kidney weighing up to 14436g, and Schacht reported a cystic kidney weighing 7248g. The external appearance of polycystic kidney is often irregular cystic nodules, and the cross-section shows numerous cysts of different sizes in a honeycomb-like pattern.

　　The cysts of infantile (PotterⅠtype) polycystic kidney are needle-sized, with very little renal tissue between the cysts. When the cysts enlarge, the renal parenchyma atrophies due to compression, leading to underdevelopment of the medulla and cortex. The cysts contain yellowish-brown mucoid, purulent, or bloody fluid, and the cysts are not connected with the renal pelvis; in the adult type, the cysts are rich in normal renal tissue and can connect with the renal pelvis (the adult type is PotterⅢtype). Kasper et al. reported PotterⅡtype polycystic kidney, most of which are in the left kidney, generally without clinical symptoms, and may also have renal pelvis ureteral obstruction or atresia. In other two types, the renal pelvis and ureter are often narrowed due to compression but not blocked; interlobular artery branches also show significant signs of compression. The cyst wall is composed of cuboidal epithelial cells with secretory function, and there are many small arteries below them. These vessels can cause hematuria due to increased pressure and rupture.

　　2. Simple renal cyst disease (simplecystickidneydisease) is a common clinical disease, the incidence increases in people over 50 years old, and the etiology is unknown.

　　3. Nephromegaly is related to autosomal recessive hereditary disease or autosomal dominant hereditary disease, and there are also other unknown factors.

　　Two, Pathogenesis

　　1. Polycystic kidney disease: The pathogenesis of this disease is unclear. Hildebrand et al. believe that polycystic kidney disease may originate from the expansion of Bowman's capsule or from the expansion of renal collecting tubules, and it is due to the obstruction of communication between the glomeruli, renal collecting tubules, and Wolffian ducts developed from the metanephric blastema; Bialestack proposed that some cysts are abnormally enlarged renal units called macroureners. Some cysts are also believed to have excretory function; Bricker et al. conducted chemical analysis of the fluid in the cysts, proving that the components contained are similar to urine; Norris et al. believe that it is due to many temporary metanephric units that cannot atrophy normally, some renal units develop local narrowing and segmentation, thus forming cysts of different sizes; Hepler et al. believe that the abnormal distribution of renal blood circulation causes renal parenchymal degeneration; Hidd-brant believes that the secretory part (originating from the renal tubules and some glomeruli of the renal tissue) and the excretory part (originating from the ureteric bud, renal pelvis, etc.) lose contact with each other during the developmental period, the secretory part becomes a blind end, and its secretions cannot be excreted, so multiple cysts are formed; others believe that mechanical factors such as local inflammation during fetal development cause fibrous obstruction of the excretory duct, or due to the obstruction of casts and insoluble calcium salts, causing the urine to flow poorly and leading to the enlargement of renal tubules. There are also two other explanations that can account for some clinical phenomena:

　　(1) Lambert conducted detailed studies on the kidneys of infants and adults with cystic kidneys through continuous renal sectioning, indicating that the cysts of polycystic kidneys have three morphological types and origins: ① glomerular cysts; ② tubular cysts; ③ excretory duct cysts. The cyst wall is lined with cuboidal or flat cells, the interstitium is rich in fibrous connective tissue, both the medulla and cortex are underdeveloped, and most of the normal renal units have disappeared; he found that all the cysts in the cystic kidneys of infants that are connected to the straight tubules of the kidney do not communicate with the functional convoluted tubules, and renal units with cysts have no function; while in the case of adult renal disease, in addition to the above types of cysts, some cysts grow from functional renal tubules and renal pelvis, the normal renal tissue between the cysts is extremely abundant, and there is functional activity, so there may be no clinical symptoms in the early stage, even when the adjacent renal tissue is compressed and atrophied, it can still maintain function until the cysts continue to grow, causing compressive renal atrophy, leading to renal function decline and death. Only the etiology still does not have an appropriate explanation.

　　（2）Dammin认为腺系统在正常胚胎发育时都有过多的腺管上皮细胞形成，而在继续发育期，腺管上皮细胞一般都会退化、消化和消失，而退化的初期是完成上皮管的分节，若分节孤立而不退缩，则囊肿形成，即肾囊肿中肾小管近端形成的分节状扩张，它仍与肾小球之滤液相通，这与以往认为后肾胚叶与输尿管胎芽不能连接的学说相反，且能解释多囊肾可以有肝、脾、胰、甚至卵巢、子宫、膀胱的多发性囊肿病的现象。

　　(2) Dammin believes that there are excessive tubular epithelial cells formed in the adenoid system during normal embryonic development, and during the period of continued development, the tubular epithelial cells generally regress, digest, and disappear. The initial stage of regression is to complete the segmentation of the epithelial tubes. If the segmentation is isolated and does not retreat, cyst formation occurs, that is, the segmented expansion formed near the renal tubules in the renal cysts still communicates with the filtrate of the glomerulus. This is contrary to the previous theory that the metanephric primordium and the ureteric bud cannot connect, and can explain the phenomenon that polycystic kidney disease can have multiple cystic diseases in the liver, spleen, pancreas, even ovaries, uterus, and bladder.

　　2. Simple renal cyst: The pathogenesis may be postnatally formed renal tubular diverticula.

　　Cystic kidney disease is prone to what kind of complications

　　1. Main complications of polycystic kidney disease

　　1. Kidney stones: The pain in the lumbar region of this disease is usually dull, and when it is accompanied by colic pain and gross hematuria, it indicates the complication of kidney stones.

　　2. Other organ multiple cysts: About half of the ADPKD patients discovered in middle age have polycystic liver, and about 70% after the age of 60. It is generally believed that its development is slower and about 10 years later than that of polycystic kidney disease. The cysts are formed by the dilatation of the atretic bile ducts. In addition, the pancreas and ovaries may also have cysts, and the incidence rate of colonic diverticula is also relatively high.

　　3. Cerebral基底动脉环血管瘤: 10% to 40% of patients with this angioma are commonly found due to angioma rupture, cerebral hemorrhage, and further examination. In addition, aortic aneurysm of the chest aorta and valvular heart disease (such as valve insufficiency and prolapse) are also relatively common. In infantile polycystic kidney disease, portal hypertension and pulmonary alveolar hypoplasia may be accompanied.

　　4. Hypertension or recurrent urinary tract infections and other complications.

　　2. Complications of solitary cystic kidney

　　Mainly due to the compression of the renal artery by the cysts located at the renal hilum, which can cause an increase in plasma renin and lead to hypertension; or cause renal pelvis obstruction and secondary infection.

　　3. Complications of medullary cystic kidney disease

　　1. Medullary sponge kidney (Medullary Sponge Kidney) mainly has complications such as kidney stones and kidney infections.

　　1. Clinical manifestations of polycystic kidney disease

　　The size and shape of the kidneys are normal or slightly larger in childhood, and with the increase of age, the number and size of the cysts gradually increase and enlarge. In most cases, symptoms appear when the kidney volume increases to a considerable extent at the age of 40 to 50, mainly manifested as bilateral renal enlargement, renal pain, hematuria, and hypertension.

　　1. Renal enlargement:The renal lesions on both sides progress asymmetrically, with varying sizes. In the late stage, the two kidneys can occupy the entire abdominal cavity. The renal surface is covered with many cysts, making the renal shape irregular, uneven, and relatively hard.

　　2. Renal pain area:It is an important symptom, often presenting as a sense of pressure or dull pain in the lumbar and back area, but can also be severe pain. Sometimes it can be abdominal pain. The pain can be exacerbated by physical activity, prolonged walking, prolonged sitting, etc., and can be relieved after lying down. Renal hemorrhage, stone movement, or infection can also be the cause of sudden severe pain.

　　3. Hematuria:About half of the patients present with microscopic hematuria, and there may be paroxysmal gross hematuria, which is caused by the rupture of blood vessels in the cyst wall. When bleeding is severe, blood clots passing through the ureter can cause colic pain. Hematuria is often accompanied by leukocyteuria and proteinuria, with a small amount of protein, generally not exceeding 1.0g/d. Pyuria is marked when there is renal infection, hematuria worsens, and there are back pain and fever.

　　4. Hypertension:It is a common manifestation of ADPKD. Before the serum creatinine level increases, about half of the patients develop hypertension, which is related to the compression of surrounding tissues by cysts, activating the renin-angiotensin-aldosterone system. In the past 10 years, Graham PC, Torre V, and Chapman AB have all confirmed that the normal tissue within the kidney, the adjacent stroma near the cysts, and the renal epithelial cells of the cysts have an increased number of renin granules and increased renin secretion, which are closely related to the growth of cysts and the occurrence of hypertension. In other words, patients with hypertension have faster cyst growth, which can directly affect the prognosis.

　　5. Renal insufficiency:Renal insufficiency will eventually occur in this disease, and individual cases may present with renal failure in adolescence. Generally, renal function decline is rare before the age of 40, about half of patients still maintain renal function at the age of 70, but the process to renal failure is greatly shortened in patients with hypertension. There are also individual patients who can maintain renal function at the age of 80.

　　6. Polycystic liver:About half of ADPKD patients discovered in middle age have polycystic liver, and about 70% after the age of 60. It is generally believed that its development is slower and about 10 years later than polycystic kidneys. The cysts are formed by the dilatation of the biliary ducts of the labyrinth. In addition, cysts can also occur in the pancreas and ovaries, and the incidence of colonic diverticula is relatively high.

　　7. Cerebral basilar artery ring hemangioma:About 10% to 40% of patients with this disease have hemangiomas. Hemangiomas are often discovered due to rupture, followed by cerebral hemorrhage. In addition, thoracic aortic aneurysms and valvular heart disease (such as incomplete valve closure and prolapse) are also relatively common.

　　Adult polycystic kidney disease (ADPKD) usually presents symptoms in early adulthood, often with hematuria, hypertension, or renal insufficiency. Larger polycystic kidneys can be detected through abdominal palpation. Renal function often deteriorates slowly, hypertension, obstruction, or pyelonephritis are important factors accelerating renal function damage. Autosomal recessive inheritance type (infantile type) polycystic kidney disease occurs in infancy and is relatively rare clinically. Most patients die in infancy, and a few mild cases can survive into adulthood.

　　The degree of anemia in this disease is often milder than that caused by other reasons leading to uremia, as renal cysts generally produce erythropoietin.

　　Second, simple kidney cyst

　　The disease often manifests in adulthood, generally without clinical symptoms, does not affect renal function, and occasionally patients seek medical attention due to hematuria. The vast majority of patients are discovered incidentally during B-ultrasound or CT scans. Urinalysis is normal, hematuria is rare, and if it occurs, there are three possible causes:

　　1, Concurrent malignant tumors;

　　2, Urinary tract infection caused;

　　3, Cyst rupture, often accompanied by renal area pain.

　　Large cysts can also cause pain or discomfort in the renal area. Large cysts (greater than 5 cm in diameter) can compress the surrounding normal renal tissue, reduce local blood flow, increase renin secretion, and cause hypertension, but renal function tests are generally within the normal range.

　　For this disease, the main task of clinical physicians is to differentiate it from other types of renal cystic diseases, especially to exclude cystic tumors. Whether simple renal cysts can cause hematuria is controversial. Some scholars believe that the hematuria in patients with this disease may be caused by other accompanying diseases. In a few patients with simple renal cysts, high-renin hypertension may be caused by the cyst located at the renal hilum.

　　The clinical manifestations of renal medullary cystic disease are as follows

　　1, Medullary sponge kidney:This disease is present at birth but asymptomatic. Urinalysis and renal function are normal. The clinical manifestations are mainly caused by complications, such as kidney stones and kidney infections. Therefore, it is often due to acute colic, hematuria, urinary tract irritation symptoms, pyuria, etc. The disease is found during further examination. In patients with extensive cystic lesions, there may be a decline in urine concentration and acidification function, increased urinary calcium excretion, good prognosis, and rare occurrence of renal failure.

　　In the past, most patients were diagnosed by IVP because half of the patients have kidney stones. An array of radiating stones in the papillary area is found in the abdominal X-ray film. The contrast medium enters the cystic cavity of the papilla, forming a rose-like pattern. The renal calyces are often enlarged and wide, and the renal shape is normal or slightly enlarged.

　　2, Juvenile renal medullary cystic disease:Most cases of this disease begin in childhood or adolescence. Clinically, the characteristic early manifestation is the decline in urine concentration function before renal failure, with symptoms such as thirst, polydipsia, polyuria, and enuresis. The urine may have no abnormalities except for hyponatremia. Growth and development may be delayed, accompanied by anemia, poor renal sodium conservation function, frequent occurrence of hyponatremia and insufficient blood volume, increased urinary calcium excretion, leading to hypocalcemia and tetany. It can also lead to hyperparathyroidism and renal osteodystrophy. The disease gradually develops to renal failure over 5 to 10 years after onset.

　　This type is a common cause of end-stage renal disease in children and adolescents, and may be a group of associated diseases. In addition to renal lesions, patients or family members may have pigmentary retinopathy, cataracts, macular degeneration, myopia, or nystagmus, etc.; adult onset medullary cystic disease is an autosomal dominant inheritance, with similar renal pathological changes in all four types, characterized by tubular atrophy, interstitial fibrosis, glomerulosclerosis, and small interstitial cysts.

　　For patients with cystic kidney disease, since there is no effective treatment, the main preventive goal is to prevent kidney complications and maintain renal function. Patients with this disease should avoid close contact activities, especially collisions and compressions, to prevent the rupture of cysts.

　　Patients with this disease are prone to hypertension, urinary tract infections, and urinary system stones, especially women. If pyelonephritis or cyst infection is induced, the pain in the renal area will worsen with marked fever, hematuria, and pyuria. In severe cases, it can lead to urinary sepsis. Therefore, it is necessary to actively treat symptoms and provide supportive care, control hypertension, prevent urinary tract infections, and prevent complications such as kidney stones, in order to extend the normal survival period of the patient as much as possible.

　　Other cystic kidney diseases:

　　1. Acquired cystic kidney disease:It is not a congenital hereditary disease but a secondary renal cystic disease occurring in patients with chronic renal failure, commonly seen in dialysis patients.

　　In 1997, Dunnill and others found renal cysts (previously without cysts) in patients undergoing maintenance hemodialysis. The occurrence of cysts is not related to age, but closely related to the duration of dialysis. The incidence rate increases with the course of chronic renal failure, with most patients developing acquired renal cystic disease after 5 years of dialysis. The incidence rate in patients with less than 3 years of dialysis is 44%, for those dialyzing for 3 years or more is 75%, and for those dialyzing for more than 8 years is 92%. These cysts can develop into cancer, so regular CT scans should be performed for long-term dialysis patients.

　　The formation mechanism of renal cysts in this disease may be obstruction caused by compensatory hyperplasia of glomeruli and tubules of residual renal units. The patient's kidneys may increase or decrease in size. Cysts are mostly located in the renal cortex, but can also be in the medulla.

　　If there are no symptoms, no special treatment is needed. If the cyst is infected or bleeding, there may be lumbar pain and hematuria. Antibacterial treatment should be strengthened during infection, and hemodialysis should be carried out during bleeding. Heparin should be reduced or not used. If severe bleeding does not stop or there is a change in cancer, nephrectomy should be performed.

　　2. Solitary polycystic renal cyst:This disease is found in polycystic large cysts in a single kidney, also known as benign cystic nephroma (benign cystic nephroma) and papillary cystadenoma. It usually occurs in a unilateral kidney, with large cysts. B-ultrasound can make the diagnosis. It should be differentiated from Wilms' tumor or neuroblastoma commonly seen in pediatrics that occur in a single kidney. The best treatment is partial nephrectomy.

　　3. Zellweger syndrome, also known as brain, liver, and kidney syndrome:It is an autosomal recessive genetic disease. Low muscle tone in newborns is an outstanding feature, with absence of suckling reflex and patellar reflex, prominent forehead, large fontanelle, fatty eyelids, widened palpebral fissure slanting upward, glaucoma, cataracts, corneal opacity, nystagmus, low nasal bridge, liver enlargement, liver dysfunction, small cysts in the renal cortex, proteinuria. Developmental and mental disorders are common, and most die before 6 months of age, with no effective treatment.

　　4. Tuberculosis Sclerosis, also known as Boumeville disease:It is an autosomal dominant genetic disease, with 80% of patients having sporadic cases. The clinical features include sebaceous adenomas, intellectual disability, and epilepsy. Malformations can occur in various internal organs, with more than 3/4 of cases having renal malformations and cysts. We encountered a 27-year-old female patient with a history of epilepsy since childhood. She was admitted due to acute abdominal pain. During surgery, both kidneys were found to be enlarged, with the right kidney being 3 to 4 times larger than normal, with two pigeon egg-sized cysts on the surface. After a comprehensive examination, there were brown sesame seed-like rash on both sides of the nostrils, shark skin spots on the sacrum, hypopigmented spots on the left forearm and right lower leg. IVP showed enlargement of the renal pelvis and calyces with arched pressure marks. Blood red blood cell count was 1.21×10^12/L, hemoglobin 36g/L, creatinine 903.7μmol/L, and proteinuria.

　　This condition is mainly treated symptomatically to control epilepsy seizures and intellectual development. Tumors causing symptoms should be considered for removal, as should cysts.

　　5, Von Hippel-Lindau syndrome:Also known as familial retinal and intracranial cavernous angioma, it is an autosomal dominant inheritance. This tumor can also be cystic, such as in the kidneys, pancreas, and adrenal glands, which can produce cysts. Clinically, it is characterized by increased intracranial pressure and symptoms of the cerebellum. The retina can show red or yellow spherical masses, hemorrhage, and exudation. It usually occurs between the ages of 30 and 40. This is a benign tumor and can be removed by surgery. Cyst aspiration is prone to recurrence. Retinal lesions can be treated with thermotherapy, radionuclide, cryotherapy, or laser treatment.

　　6, Asphyxiating thoracic dysplasia:Also known as Jeune syndrome, it is mainly characterized by narrow chest and short limbs with polydactyly in newborns, with fixed chest, leading to dyspnea and cyanosis. Another non-lethal type is characterized by renal damage, leading to chronic renal failure in the end. Renal lesions are chronic nephritis with cysts. This disease is autosomal recessive inheritance, and half of the children die of pneumonia and asphyxia in childhood. Survivors can consider surgical reconstruction of the chest. Later treatment mainly focuses on chronic nephritis and renal failure.

　　7, Senior-Loken syndrome is also known as familial renal retinal dystrophy:Reported by Senior-Loken in 1961, renal lesions resemble cystic medullary disease with retinal pigmentary degeneration. It is an autosomal recessive genetic disease, and the cysts are mainly located at the junction of the renal cortex and medulla and in the medulla. There is renal interstitial fibrosis and infiltration of inflammatory cells, eventually leading to end-stage renal atrophy. Early symptoms include polydipsia, polyuria, and nocturia, and later symptoms include azotemia and severe anemia, accompanied by hypertension and edema. Diagnosis is easy based on renal damage and characteristics of fundus (retinal degeneration). Electroretinography or electrooculography is valuable for early diagnosis. There is no specific treatment for this disease.

　　8, Parotid, ear, and kidney syndrome is abbreviated as BOR syndrome:It is an autosomal dominant genetic disease. There are symmetrical fistulas or small nodules in front of the sternocleidomastoid muscles on both sides. The auricles are thick and cup-shaped, with exostoses in front of the ear, accompanied by various hearing impairments, and bilateral polycystic kidneys with other urinary tract malformations. This disease can only be treated symptomatically, and plastic surgery can correct ear deformities and anterior neck fistulas. Hearing aids can be used for hearing impairments.

　　9, Ehlers-Danlos syndrome is a group of genetic connective tissue diseases:There are more than 10 types, and renal damage is seen in type Ⅸ. In childhood, there are excessive stretching, relaxation, ptosis, and mild skeletal abnormalities of the skin. Bladder diverticula, hydronephrosis, and renal cysts, as well as significantly reduced serum copper and ceruloplasmin, decreased lysyl oxidase in fibroblasts of the skin, can make an accurate diagnosis. This type is X-linked recessive inheritance. There is no specific treatment, skin cracks should be carefully sutured, and the retention time of the suture should be extended. Joint dislocation can be corrected by surgery. Urinary tract infections should be treated promptly with antibacterial drugs.

　　In addition, kidney cysts are often found in conditions such as Oro-Facio-Digital Syndrome type I (Oro-Facio-Digital Syndrome I), 18-Trisome Syndrome (18-Trisome Syndrome, Edward Syndrome), and Meckel Syndrome, as well as in renal B-ultrasound or CT examinations. Since these genetic diseases often involve multiple malformations, diagnosis is not difficult, and there is no specific treatment. However, differentiation should be made in renal cystic diseases.

　　10, Multicystic renal agenesis:It is a common complete renal agenesis, a common congenital disease in children, characterized by congenital renal malformation with cyst formation, often occurring unilaterally. There is no family history of the disease. Clinically, it is one of the common causes of neonatal abdominal masses. Ultrasound and CT examinations show that the affected kidney has an abnormal shape, with irregular cysts of varying sizes, and the contralateral kidney may compensate for enlargement.

　　The disease is commonly known as multicystic kidney disease (Mmulticystic Kidney Disease), and this term is easily confused with Polycystic Kidney Disease in Chinese, so it is now rarely used.

　　The disease is the most common cystic disease in infants, and abdominal masses are present at birth. Most cases are unilateral lesions, where the kidneys are replaced by cysts of varying sizes, losing their normal shape. The affected kidney can be large or small, but it is non-functional, often with ureteral obstruction and compensatory hypertrophy of the contralateral kidney. The cyst wall may not be translucent. In addition to the kidneys, other malformations may also be present.

　　There is no specific treatment for the disease, and the prognosis is good after unilateral lesion nephrectomy. Bilateral lesions are often unable to survive and die early.

　　11, Hereditary neurofibromatosis:The disease is also known as Von Hippel-Lindau syndrome, an autosomal dominant genetic disorder characterized by multiple organ cysts and tumors.

　　12, Pyelocaliceal cyst:The disease is also known as pyelogenic cyst (pyelogenic cyst) or pelvis diverticulum (pelvic diverticulum), which may be a congenital disease. Larger cysts can cause lumbar pain and pyelonephritis due to compression and obstruction, with symptoms recurring. Stones may be visible within the cyst.

　　13, Pericalyceal lymphovascular dilation:The disease is also known as peripelvic cyst (parapelvic cyst), which is formed by the expansion of lymphatic vessels around the pelvis and renal calyces. Most cases are asymptomatic, and a few may complicate with obstruction, infection, and calculus.

　　14, Perirenal pseudocyst:The disease is a pseudocyst found within the renal fascia, caused by renal cyst rupture and some surgical conditions.

　　15, Tumorous renal cyst/carcinoma:It is rare in the general population, but it can be seen in a few patients with renal cysts found during dialysis treatment, of whom 4% are tumorous renal cysts.

　　The disease occurs in adulthood, with about 70% of patients being male.

　　The etiology of the disease may be related to genetic abnormalities. In renal cystic diseases with genetic abnormalities, such as tuberous sclerosis and hereditary neurofibromatosis, the incidence of tumorous renal cysts is higher than that of other renal cystic diseases.

　　The pathogenesis is due to the rapid growth of renal tumors, which can lead to ischemia and cystic transformation in the center. Some tumorous renal cysts have thin walls and appear cystic, possibly originating from the original simple (benign) cysts that have undergone malignant transformation.

　　Tumorous renal cysts manifest as hematuria, accompanied or not accompanied by lumbar pain, and palpable masses in the lateral abdomen. Ultrasound examination can usually differentiate simple renal cysts from tumorous renal cysts. When B-ultrasound cannot clearly differentiate between simple and tumorous renal cysts, CT, MRI, and fine needle aspiration of the cyst are required.

　　In a small number of dialysis treatment patients with this disease, when renal cysts and hematuria are found, this disease should be suspected. The diagnosis can be confirmed by combining the results of laboratory tests, ultrasound examination, CT, MRI, and fine needle aspiration of the cyst.

　　The treatment of this disease is partial or total nephrectomy.

　　First, polycystic kidney disease

　　1. Pathophysiological changes of polycystic kidney disease:This disease usually affects both kidneys, and it is rare for only one side to be affected. The weight of a normal adult kidney is about 150g. In asymptomatic adult polycystic kidney disease patients, the average weight of a single polycystic kidney is 256g; in symptomatic adult polycystic kidney disease patients, the average weight of a single polycystic kidney is 465g. In adult polycystic kidney disease, the kidneys are commonly弥漫性 cysts, regardless of the distribution of the renal cortex and medulla, they are filled with cysts of different sizes, resembling a cluster of grapes. The cyst wall epithelial cells have localized hyperplasia, forming polypoid, abnormal hyperplasia of extracellular matrix, and cyst formation due to the dilatation of the proximal tubules. The components of the cyst fluid are similar to plasma; the cysts formed by distal tubules have lower sodium and chloride content, while the concentration of urea and creatinine is higher. In patients with symptomatic polycystic kidney disease, with the increase of age, the number of cysts increases, the cyst cavity becomes larger, reaching 2-3cm in diameter, and the long diameter of the kidney in the later stage can reach 20-30cm. The whole kidney is almost occupied by cysts, and it is common for cysts with a diameter of more than 3cm to contain bloody fluid or blood clots.

　　The cross-section of polycystic kidney shows that cysts are uniformly distributed in the cortex and medulla, and the renal pelvis and calyces are often significantly deformed. In severe cases, almost no obvious residual renal tissue can be seen, but in patients with mild symptoms, this disease is often confused with multiple simple cysts (such as simple renal cysts, solitary multilocular cysts).

　　Microscopic observation shows that normal renal tissue is compressed by adjacent cysts, and secondary glomerulosclerosis, tubular atrophy, and interstitial fibrosis occur on the basis of vascular sclerosis or pyelonephritis. It is difficult to identify the tissue source of the cyst, unless the cyst maintains the normal position of the original tissue and the morphological characteristics of the epithelium. Cysts originating from the renal capsule sometimes contain deformed loop-like glomerular vascular丛; cysts originating from the deep collecting system are usually thin-walled; cysts occurring in the subcapsular collecting system have thicker walls and are often surrounded by dense fibrous connective tissue. Specific plant agglutinin binding test can help identify the tissue source of the cyst as proximal tubules, collecting tubes, or others.

　　2. Imaging examination:Including X-ray abdominal plain film examination, CT and MRI examination, contrast examination [intravenous pyelography (IVP), ureteropyelography, radionuclide renal imaging] as routine examination methods, this disease can be detected by pyelography (if the kidney lacks excretion function, then retrograde imaging is required) examination, early stage can find the renal pelvis end半月状畸形 caused by the pressure of the renal pelvis due to the cyst; in the late stage, the renal pelvis and calyces extend, the calyces become wider, and the boundaries are obvious. Other examinations such as abdominal X-ray plain film show significant changes in the size of the kidneys on both sides, and there are cystic or calcified shadows.

　　CT and MRI are generally not used as initial examination methods because they involve a large amount of radiation and are expensive. However, their advantages are that they can display the different densities of tissues, provide detailed anatomical structure information, CT can better clarify the location and nature of the lesions, and is a helpful examination method. It is replacing the traumatic retrograde and antegrade pyelography. MRI is like CT and can more clearly display the density of various tissues, clarify the causes of obstruction and the nature of the lesions.

　　3. Ultrasound examination:Ultrasound examination is very effective in diagnosing dilated renal pelvis and calyces. It is the preferred examination method for diagnosing renal cystic changes and hydronephrosis. As this is a non-invasive examination, it has high sensitivity for diagnosing renal cystic changes and is also suitable for the examination of polycystic kidneys. Ultrasound examination can detect increased kidney volume, cysts, and significant deformation of the renal pelvis and calyces. In addition, ultrasound can be used for the screening of this disease.

　　Second, simple kidney cyst

　　1. Pathological examination:They can be seen in unilateral or bilateral kidneys, and the cysts can be single or multiple, but generally not more than 5 in each patient. The cysts can be located in the renal cortex or medulla, not communicating with the renal pelvis, with thin walls, clear boundaries, and yellowish transparent fluid inside the cyst. There are no red blood cells or white blood cells, and calcification may occur in the cyst wall.

　　2. Ultrasound examination:It shows that simple kidney cysts are liquid dark areas, which can be solitary or multiple, and can be unilateral or bilateral.

　　3. CT, MRI examination and fine needle aspiration examination:The CT and MRI manifestations of tumor cystic kidney are different from those of simple kidney cysts. Tumor cystic kidneys often have thick walls, irregular cyst walls, echo areas within the cystic tumor, no echo enhancement on the posterior wall, and the interface between the cyst and renal parenchyma is not smooth, the boundary is not clear enough. After intravenous injection of contrast agent, enhancement shadows may appear. The fluid in the tumor cystic kidney is hemorrhagic or black, and tumor cells, lactate dehydrogenase, and cholesterol levels are increased.

　　Third, medullary cystic disease

　　1. Imaging examination:Routine examination methods include X-ray abdominal flat film examination, CT and MRI examination, contrast examination (venous pyelography, ureteral pyelography, radionuclide renal imaging), etc. This disease can be detected by renal pelvis imaging (if the kidney lacks excretion function, then retrograde imaging is required). Early stages may show crescent-shaped deformities at the ends of the renal calyces due to compression by cysts. In the late stage, the renal pelvis and calyces extend, the renal calyces widen, and the boundaries are distinct. Other examinations, such as abdominal X-ray flat film, can show significant changes in the size of the kidneys on both sides, and there are cystic or calcified shadows.

　　CT and MRI are generally not used as initial examination methods, but their advantages are that they can better clarify the location and nature of the lesions, and can more clearly display the density of various tissues, clarify the causes of obstruction and the nature of the lesions, and are beneficial for excluding urinary tumors and other lesions.

　　2. Ultrasound examination:Changes in kidney volume, deformation of renal pelvis and calyces, and thick cyst walls or varying degrees of calcification and obstruction can be found.

　　The occurrence of cystic kidney disease is closely related to daily life. Unhealthy dietary habits can cause various kidney diseases, and the occurrence of cystic kidney disease is one of them. Regarding the occurrence and development of cystic kidney disease, the impact of dietary conditions can be divided into the following points:

　　1. Irregular diet:If one is too hungry, it will lead to insufficient nutrition; if one is too full, it is easy to injure the digestion and absorption function of the spleen and stomach, and cause obstacles in the circulation of Qi and blood; if one eats too much rich and greasy food, it is easy to generate internal heat.

　　2. Unhygienic diet:Mild cases can lead to gastrointestinal diseases, while severe cases can cause poisoning and even threaten life.

　　3. Dietary preferences:If one eats too much cold and cool foods, it is easy to injure the spleen and stomach Yang; if one eats too much spicy and warm foods, it can cause heat in the gastrointestinal tract; in addition, if one has a preference for the five flavors, it is easy to injure the internal organs over time.

　　The effects of these dietary habits on the body are evident. They also directly or indirectly affect the changes and development of cystic diseases. For cystic diseases, in clinical practice, we especially emphasize the following aspects: spicy and stimulating foods such as chili, alcohol, smoking (including passive smoking), chocolate, coffee, sea fish, shrimp, crabs, etc. 'Stimulants'; salty foods, especially preserved foods; contaminated foods such as unhygienic foods, rotten and deteriorated foods, leftover meals and dishes; grilled foods; in addition, animal high-protein, high-fat, and greasy foods, i.e., the aforementioned 'rich and greasy' foods should also be restricted, and soybeans and soy products should be restricted, especially for patients with renal insufficiency who need to pay more attention.

　　First, treatment

　　1. Treatment of polycystic kidney disease:There is no specific treatment for this disease, mainly to control blood pressure and infection to effectively delay the progression of renal failure. Symptomatic treatment is given to cases that are not suitable for surgery, and the treatment of renal insufficiency patients is the same as that for chronic renal failure. Renal colic attacks can be treated with various analgesics, and antibiotics are used for concurrent infections. It is also possible to adopt a combination of traditional Chinese and Western medicine to treat this disease, and clinical observations have shown good efficacy, providing a treatment approach for cases that are not suitable for surgery. Common measures for symptomatic and supportive treatment include:

　　(1) Antihypertensive treatment: Good control of hypertension can improve the prognosis of patients. Currently, angiotensin-converting enzyme inhibitors (ACEIs) should be the first choice. Captopril, Enalapril, Cilazapril, Benazepril, and Perindopril commonly used in China are mainly excreted by the kidneys, although the latter two are partially cleared by the liver and gallbladder. When the GFR is less than 30ml/min, the dosage should be reduced. Fosinopril is cleared by both the liver and kidneys, and when the renal clearance rate decreases, the liver clearance rate increases, maintaining the total clearance rate relatively stable. Clinical evidence shows that various degrees of renal insufficiency do not require dose adjustment. The short-acting first-generation product Captopril, although it has many side effects, acts quickly and the sublingual administration takes about 10 minutes to start lowering blood pressure. ACEIs can inhibit the activation of angiotensin II by multiple growth factors, and whether it can inhibit the growth of cysts still needs further research and observation.

　　Other antihypertensive drugs such as calcium channel blockers, beta-blockers, and vasodilators can be used, or combined with ACE inhibitors.

　　(2) Prevention and treatment of urinary tract infections and kidney stones: Effective antibiotics should be selected and actively administered for anti-infection treatment, the main purpose of which is to treat complicated acute pyelonephritis, and a few for prophylactic use. Patients with this disease are prone to urinary tract infections, especially women. If pyelonephritis or cyst infection is induced, the pain in the renal area will worsen with fever, and hematuria and pyuria will be obvious. In severe cases, it can lead to urinary tract sepsis. Therefore, it is necessary to treat actively. Antibiotics should be selected that can easily enter the cyst cavity, such as macrolide antibiotics, sulfamethoxazole/trimethoprim (SMZ-TMP), and quinolones, which are easy to enter the cyst cavities of the proximal and distal tubules. For cysts in the proximal tubules, penicillin and cephalosporin classes are often selected.

　　According to statistics, the incidence of kidney stones and renal calcification in this disease is about 20%, and a decrease in urinary citrate may be a cause of increased stone formation. Stones can cause urinary tract obstruction, renal colic, hematuria, and worsen renal function damage, and are also an important factor in recurrent infections. Drinking plenty of water, frequent urination, and alkalinizing urine are important measures for preventing stones and calcification.

　　(3) Treatment of intracystic hemorrhage: Larger kidney stones or obstructions can cause hematuria, and surgical treatment should be considered. Persistent gross hematuria or massive hemorrhage can be treated with aprotinin or desmopressin acetate. Renal artery embolization may be considered if necessary. Aprotinin intravenous or intracystic injection is the most effective for intracystic hemorrhage in polycystic kidneys. In the absence of aprotinin, thrombin (Ligustrin) intravenous or intramuscular injection and hemostatic drugs acting on the vascular wall can be used. Intravenous infusion of a large amount of protamine sulfate is also effective.

　　(4) Surgical treatment: Once symptoms appear in this disease, the lesions are often in the late stage, and surgical treatment should be considered. It is not suitable for surgical treatment for patients with purulent cysts or massive hemorrhage. Some people use deep cyst decapitation decompression surgery, which is effective for treating adult polycystic kidney disease. It can be considered for renal perinephric abscess, subarachnoid aneurysm hemorrhage, or giant kidneys.

　　(5) Renal replacement therapy: Currently, the sufficiency and individualization of modern dialysis technology have made the prognosis of patients with polycystic kidney disease quite good internationally. With the promotion and popularization of modern dialysis technologies such as HDF and Biofiltration in China, an increasing number of patients with polycystic kidney disease are expected to survive for a long time.

　　(6) Cyst decompression surgery: For patients with large cysts and severe hypertension, renal insufficiency, or continuous pain in the renal area, cyst decompression surgery can be considered. Cyst puncture and decompression can be guided by B-ultrasound. After fluid decompression, tetracycline solution (5% 5-20ml) or sclerosing agents such as 50% glucose solution, 70% alcohol, or 80% glycerin can be injected. The shrinkage or closure of the cyst can reduce the pressure on the renal tissue, improve renal ischemia, and can relieve pain in some patients, as well as improve hypertension or renal function.

　　2. Treatment of Simple Renal Cyst:Generally, there are not many renal cysts, the cyst cavity is not large, the kidney function is normal, and treatment is usually not necessary. Regular复查B-ultrasound is necessary. If pyelonephritis occurs, it should be considered that the cyst may be infected. Quinolones such as ofloxacin (fluoroquinolone) 0.3-0.4g, twice a day, or sulfamethoxazole/trimethoprim (SMZ-TMP) 1.0g, twice a day, for a total of 10-14 days as one course of treatment. Anti-inflammatory analgesics can be used for renal area pain. If the cyst is located at the renal hilum and compresses the renal artery or causes renal pelvis obstruction, and hypertension and a large cyst (diameter < 5cm) with symptoms, consider puncture aspiration of the cyst fluid to eliminate hypertension and obstruction. After each puncture aspiration, 2-5ml of anhydrous alcohol should be injected according to the size of the cyst to gradually reduce the size of the cyst. Generally, multiple puncture aspirations and injections of anhydrous alcohol are needed to make the cyst tend to close. Patients often experience a decrease in blood pressure after aspiration of the cyst fluid to reduce pressure or after cystectomy. In cases with poor efficacy, surgical treatment may be necessary if necessary.

　　3. Treatment of Cystic Disease of the Renal Medulla:There is no specific treatment for this disease. Correcting electrolyte balance, especially supplementing sodium to correct hyponatremia and hypovolemia, can improve kidney function and delay the progression of renal failure.

　　If there are no symptoms and complications, no treatment is needed. If there is urinary tract infection, it should be treated with regular antibacterial therapy for pyelonephritis. Patients with concurrent stones should drink more water, keeping daily urine volume above 2000ml, and try to use stone expulsion and stone-dissolving drugs. Thiazide diuretics should be added for those with hypercalciuria. If the lesion is localized to a part of one kidney, nephrectomy of the affected kidney or the lesion site may be considered.

　　Second, Prognosis:

　　1. Polycystic Kidney Disease:The patient's kidney function often shows progressive decline, and without antihypertensive treatment, patients in the same family enter end-stage renal failure (ESRF) at similar ages. However, in 30% of polycystic kidney disease families, they may not enter ESRF until 80 to 90 years old. This indicates that the prognosis of the disease is inconsistent. If active treatment is received, the prognosis can be significantly improved.

　　2. Simple Renal Cyst:Generally, there are no clinical symptoms, which does not affect kidney function, so the prognosis is good, and it does not affect the patient's lifespan.

　　3. Cystic Disease of the Renal Medulla:If patients with the disease receive active treatment, the prognosis can be significantly improved.