Kidney cyst is a benign neoplasm, which is a fluid–filled cavity with a thin connective tissue membrane. Subjective symptoms of pathology are often absent, with the development of complications or an increase in the size of the formation, there are complaints of lower back pain, the presence of blood in the urine, fatigue, an increase in body temperature and blood pressure, which is not corrected by antihypertensive drugs. Diagnostics is performed using ultrasound of the kidneys, computed tomography, radioisotope studies of the functions of the excretory system. Treatment includes puncture aspiration of the contents, sclerotherapy of the cyst, laparoscopic excision.
ICD 10
N28.1 Kidney cyst acquired
Meaning
Kidney cyst is one of the most common conditions in urology. It is assumed that cystic changes of varying severity occur in almost a quarter of people over the age of 45 years. Men suffering from obesity, arterial hypertension, infectious diseases of the urinary system, and urolithiasis are especially predisposed to the development of pathology. Kidney disorders are detected only in a third of patients, in other cases there is an asymptomatic course. A separate type includes congenital varieties of cysts that are found in children.
Causes
Kidney cysts are a rather heterogeneous group of pathological conditions. The direct cause of the disease is considered to be disorders of the growth of epithelial and connective (interstitial) tissues caused by damage or inflammatory processes. The development of some cystic growths is explained by congenital anomalies of the urinary system or genetic features of the body. The main predisposing factors are:
- Kidney tissue damage. Inflammatory processes (glomerulo– or pyelonephritis), tuberculosis, ischemic lesions (infarction), tumors can provoke disorders of the development of epithelial tissue of the tubules of the nephron. As a result, a thin-walled cavity is formed mainly in the medulla of the kidneys.
- Age-related changes. The appearance of cysts in people over 45 years of age is explained by an increase in the load on the excretory system and the mechanism of “accumulation of disorders”. The latter arises as a result of insignificant in severity, but multiple pathological processes that enhance the influence of each other.
- Innate factors. Sometimes cysts are the result of violations of the intrauterine development of the rudiments of the kidneys. Such neoplasms are usually found in childhood, often have a multiple character. Mutations of some genes increase the predisposition to the formation of cystic cavities in the kidneys.
Systemic conditions (arterial hypertension, obesity, diabetes mellitus) contribute to the progression of the disease. They lead to a violation of blood supply and nutrition of the organs of the urinary system and, as a result, to the proliferation of connective tissue that is less demanding of oxygen access. Some types of pathology are caused not by the appearance and growth of cystic formation, but by a localized process of destruction of renal tissue (with abscess, carbuncle).
Pathogenesis
The development of the “true”, the most common kidney cyst occurs as a result of damage to the tubules of the nephron. Inflammatory or sclerotic process, organ injuries lead to the isolation of a fragment of the tubule from the rest of the initial parts of the urinary tract. Under certain conditions, there is no sclerosis of the isolated area, but a rapid proliferation of the tubular epithelium, resulting in a small (about 1-3 millimeters) bubble. It is filled with a liquid similar in composition to primary urine or filtered blood plasma.
With further cell division of connective and epithelial tissues, cyst growth occurs, sometimes reaching a size of 10-15 centimeters. Its growth is accompanied by compression of surrounding structures, sometimes it stimulates the development of secondary cystic growths. With a significant cyst size, the outflow of urine becomes difficult, blood vessels feeding the kidney are squeezed, nerve bundles are irritated. This causes a number of local and general symptoms – pain, fluctuations in blood pressure, intoxication of the body. Sometimes there is malignancy of epithelial cells of the walls of the neoplasm.
Classification
In modern urology, there are several options for classifying cystic bladders in the kidneys, based on their structure, localization, origin, and nature of the contents. Traditionally, this pathology includes conditions that are not actually a cyst – for example, dermoid tumors, abscesses in the kidneys, which have similar structural features, but a different etiology. The Bosniak classification, which considers cysts according to the risk of malignancy and includes the following options, has particularly high clinical significance:
- Category I. Simple single-chamber cysts with minimal risk of malignancy. Do not require treatment.
- Category II. Benign cysts with the presence of intracameral septa and microcalcinates, less than 3 cm in diameter. Subject to dynamic ultrasound control.
- IIF category. Cysts are benign, with a large number of thin-walled partitions, calcifications, ranging in size from 3 cm or more. They require observation, rarely malignate (about 5%).
- Category III.Cysts of complex structure with a high risk of malignant transformation (approximately 50%). They differ in an indistinct contour, thickened intracameral partitions with heterogeneous calcium deposits. Subject to prompt removal.
- Category IV. They have all the signs of malignancy: a lumpy contour, a pronounced liquid and tissue component, etc. They require immediate surgical treatment.
Localization of cystic cavities may vary – under the capsule of the organ (subcapsular), in the thickness of its tissues (intraparenchymatous), in the area of the gate or pelvis of the kidneys. The location, nature and size of the cyst are the main characteristics that influence the choice of treatment methods and prognosis of the disease.
Kidney cyst symptoms
Pathology often proceeds asymptomatically, due to the slow growth of the neoplasm – the kidney tissues have time to adapt to its presence without a noticeable loss of functionality. As the cyst grows, it begins to put pressure on the blood vessels and stimulate the juxtaglomerular apparatus. This is manifested by an increase and instability of the blood pressure level, which leads to headaches, palpitations, cardialgia. Local symptoms – pain in the lumbar region – develop with decompensation of kidney function or compression of nearby nerve trunks.
The large size of the kidney cyst contributes to the violation of urodynamics due to a decrease in the volume of the pelvis or partial compression of the ureter. At the same time, the symptoms are joined by a decrease in the amount of urine excreted, frequent urge to urinate, hematuria. The pain begins to radiate into the groin and genitals. The delay and violation of the formation of urine cause intoxication of the body, which is manifested by weakness, increased fatigue, sometimes by edema. The phenomena of renal insufficiency (fluid retention, the smell of ammonia from the mouth) occur in the case of bilateral kidney damage or the presence of only one organ.
A sharp increase in temperature, chills, fever, increased pain with a cyst in the kidney often indicate the addition of a secondary bacterial infection and suppuration of the neoplasm. Severe pain in the lumbar region, especially appearing suddenly, against the background of physical exertion, indicates the possibility of rupture of the cystic wall. The rupture may be accompanied by damage to blood vessels with the development of hemorrhage in the kidney and ischemia of its tissues. A sign of bleeding is sudden macrohematuria, in rare cases blood accumulates in the retroperitoneal space.
Complications
One of the most frequent complications of a kidney cyst is its infection with the development of suppuration, proceeding by the type of abscess or severe pyelonephritis. A significant role in the penetration of pathogenic microorganisms is played by urodynamic disorders – reflux and stagnation of urine. It is also possible to rupture the cyst with the outpouring of its contents into the cup-pelvic system or into the retroperitoneal space. It can be accompanied by renal bleeding, infection of the urinary tract or the occurrence of shock. In the long term, there is a risk of malignant degeneration of cystic formations.
Diagnostics
Detection of a kidney cyst is complicated due to a long period of asymptomatic pathology. As a result, the disease is often detected by accident. The first signs are non-specific changes in the general analysis of urine, an unexplained rise in blood pressure. With the help of various diagnostic techniques, a urologist can not only confirm the presence of a neoplasm, but also determine its type, size and localization, as well as assess the functional activity of the urinary system. For this purpose, the following studies are prescribed:
- Ultrasound of the kidneys. Ultrasound diagnostics is a common diagnostic technique used to detect cysts. They are defined as aechogenic structures. Sometimes partitions and calcifications are detected inside. Ultrasound Dopplerography (ultrasound of renal vessels) makes it possible to assess the effect of a cyst on the blood supply to the kidneys.
- CT of the kidneys. The method is used to clarify the diagnosis and differentiation of cysts with malignant tumors. Solitary formations during tomographic examination look like rounded objects with clear contours filled with liquid, multilocular varieties – like a multitude of chambers of various sizes. The introduction of intravenous contrast makes it possible to distinguish cysts from tumors, since the latter have the ability to accumulate radiopaque substance.
- Functional studies. The activity of the excretory system is studied by the method of dynamic scintigraphy. This study allows us to assess the glomerular filtration rate, additionally identify changes in the calyx-pelvic system and the initial parts of the urinary tract.
- Laboratory tests. With small cystic formations, the general urinalysis is unchanged. An increase in the size of the cyst can provoke a decrease in the volume of daily diuresis, the occurrence of nocturia, the appearance of blood impurities in the urine (hematuria) and protein (proteinuria).
Kidney cyst treatment
Mandatory surgical treatment is subject to cysts in the case of a progressive increase in their size during the year, causing pain, increased blood pressure, refractory to hypotensive therapy, as well as cysts of categories III and IV according to Bosniak. Usually, the elimination of cystic formation is performed by puncture and endoscopic techniques, which include:
- Percutaneous puncture aspiration. The essence of aspiration of a renal cyst is to insert a needle into the cystic cavity with further suction of the contents. As a result, the volume of the cyst decreases sharply, the neoplasm is sclerosed.
- Sclerotherapy of kidney cysts. The technique of renal cyst sclerotherapy is a modification of puncture aspiration. After removing the liquid contents, a solution of ethyl alcohol or iodide compounds is injected into the bubble cavity. Medications irritate the inner surface of the cystic membrane and activate the processes of sclerosis, which reduces the number of relapses.
- Surgical removal of a cyst. Radical excision of the kidney cyst consists in removing the neoplasm and suturing the remaining normal kidney tissue. It is used for large or multicameral cysts, ruptures of the shell, bleeding, severe suppuration. It is usually performed with the help of endoscopic instruments, in severe cases, open surgery may be prescribed.
In the presence of large cysts and significant damage to the kidneys, resection or nephrectomy is resorted to (subject to the normal functionality of the second organ). Auxiliary treatment includes symptomatic measures – taking painkillers, antihypertensive drugs (ACE inhibitors), antibiotics for infectious complications.
Prognosis and prevention
The prognosis of a kidney cyst depends on the nature of the neoplasm, its size and localization. In most cases, relatively small single-chamber cystic vesicles with slow growth are detected. Their presence is almost asymptomatic, characterized by favorable prospects. Treatment of such forms of pathology is not required, only periodic examination by a nephrologist is necessary for the timely detection of possible complications.
With multicameral cysts, the prognosis worsens, as the risk of malignancy and CRF increases. However, with the radical treatment of these types of pathology, relapses and complications are extremely rare. There is no specific prevention of kidney cysts, recommendations are reduced to timely treatment of inflammatory diseases of the urinary system, blood pressure monitoring and periodic medical examination by a urologist after reaching 40 years of age.