Megacalicosis is an enlargement of the kidney cups with a defect in the development of the malpighian pyramids, not associated with obstruction. Pathology is attributed to congenital diseases of the cup-medullary system of the kidney. Symptoms appear with the development of complications, including pain in the lumbar region, fever with chills, discomfort with frequent urination. Diagnosis is based on imaging studies: excretory urography, ultrasound of the kidneys, CT and MSCT with contrast. Changes in the analyses are nonspecific and indicate the severity of inflammation, renal function does not suffer. Treatment in the absence of manifestations is not required, when complications are added, the tactics are determined individually.
ICD 10
Q63.8 Other specified congenital anomalies of the kidney
Meaning
Megacalicosis (synonym “megacalix”) in practical urology is more often detected sporadically. With this condition, which occurs as a result of a violation of the processes of embryogenesis, men face 2-6 times more often. Symptoms are associated with the development of complications and manifest in adulthood. Megacalicosis was first described by the Spanish urologist A. Pugwert in 1963. Kidney damage is more often unilateral, in a number of observations megacalix is combined with other abnormalities of the development of the urinary system, and with genetic pathologies – with other extragenital malformations. Often, the generalized form of the anomaly is mistaken for an intrarenal form of hydronephrosis or genitourinary tuberculosis.
Causes
As a result of dysembriogenesis, due to improper formation of the ureteral-renal tube, the connection of the terminal part of the upper urinary tract and nephrogenic blastema is disrupted. Pathology of kidney structures during fetal development can occur at any stage, but why this happens, there is no clear answer. Predisposing factors include:
- Negative exogenous effects. Ionizing radiation, contact with toxic substances, uncontrolled administration of drugs with teratogenic effects on the fetus are considered as potential triggers for intrauterine malformations. It has been proven that alcohol abuse, chronic nicotine intoxication, taking narcotic and psychotropic substances in a pregnant woman can have a negative impact on the formation of the child’s internal organs.
- Genetic mutations. Megacalicosis is one of the manifestations of a rare genetic Schinzel-Gideon syndrome inherited by an autosomal recessive type. In addition to pathologically altered cups and an increase in their number, macrocephaly, multiple stigmas, mental retardation are characteristic of him. Similar changes in the kidneys can occur in Down and Edwards syndromes.
Pathogenesis
The kidney is a paired organ that includes parenchymal tissue, a system for collecting and excreting urine. The parenchyma consists of an external cortical substance and an internal cerebral one. The structures of the cortical layer are the renal glomeruli together with the Shumlyansky–Bowman capsule, the cerebral – tubules. The tubules form pyramids that end in a renal papilla communicating with small cups. The small renal cups (normally 6-12 of them) merge into a large renal cup (2-4), and then into the renal pelvis.
Tubular dilation (dysplasia, hypoplasia) is the basis of cup-medullary kidney abnormality. With megacalicosis, it is local (single), i.e. it occurs in one Malpighian pyramid. If several pyramids are involved in the process, we are talking about multiple megacalicosis (megapolicalicosis). Tubule extensions accompanying tubular dysplasia predispose to precipitation of calcium salts, which leads to intraparenchymal nephrolithiasis.
With megacalicosis, the size of the cups is increased several times, papillae are absent, pyramids are hypoplasized. The underdevelopment of the pyramids leads to the immersion of the cups in the medulla of the kidney. Normally, the papilla protrudes into the cup, but with this structural anomaly, it is either not there, or it is modified. The size of the kidney is normal, given the absence of an obstacle to the outflow of urine and the compensatory development of muscle fibers. The functional ability of the kidneys is not impaired or slightly slowed down.
Classification
Megacalicosis is included in the classification of anomalies of the kidney structure, in particular, it is referred to cup-medullary pathologies. The process can be ipsilateral and bilateral, complicated or without complications. Megacalicosis is sometimes present in combination with defects of other organs and systems, in this case the anomaly is called combined. According to the classification , there are:
- Dysembrioplasia of the malpighian pyramids. This anomaly is represented by the expansion of the collective tubules, their dilation with the formation of a large number of pseudocysts (another name is spongy kidney), medullary hypoplasia (local megacalicosis and generalized megapolicalicosis).
- Dysembrioplasia of the calyx. The anomaly includes calyx dystopia, an increase in their number. An atypical location in the cortical layer of the parenchyma may be in one calyx or in several (single and multiple dystopia). Ectopia of the calyx and the underdeveloped pyramid is always diagnosed from one side. Synonyms: cup diverticulum, hydrocalicosis, etc.
Symptoms
In most cases, there are no clinical manifestations with uncomplicated course. Symptoms develop with secondary infection, which is especially typical for patients with combined anomalies of the kidney structure, and include pain (aching, dull or acute) in the projection of the kidney on the affected side, an increase in temperature reaction, dysuric disorders. Of the common signs, patients are concerned about weakness, headache and bone and joint pain, and loss of appetite.
Predisposition to stone formation due to increased calcification can be clinically expressed by the periodic release of microliths with urine, cuts with frequent urination, discomfort after urination. If concretions of significant size (from 0.4 mm and above) are formed, with their independent discharge and obstruction, classical renal colic develops: acute pain in the lower back with irradiation to the lower urinary tract, nausea, frequent urge to urinate.
Complications
If megacalicosis occurs in isolation in one kidney, complications are rarely recorded. Under the influence of favorable factors (immunosuppression of any genesis) or with a combination of several renal abnormalities, an inflammatory process (pyelonephritis) develops, which takes a chronic course. Prolonged persistence of pathogenic and conditionally pathogenic flora can be complicated by impaired renal function and the addition of chronic renal failure as a result of the gradual death of nephrons.
The tendency to stone formation can lead to the development of urolithiasis, up to staghorn calculus. Compensatory capabilities of the calyx muscles are lost, and urine begins to stagnate. Secondary infection with stone formation in the absence of timely urological care often leads to the addition of acute purulent calculous pyelonephritis, the formation of a kidney carbuncle or the appearance of multiple aposema. Nephrectomy is performed to normalize the patient’s condition and prevent urosepsis.
Diagnostics
There are no pathognomonic complaints that make it possible to suspect megacalicosis. Pathology is detected accidentally when pyelonephritis, urolithiasis is suspected more often during ultrasound scanning of the kidneys and often has a similar visual picture with tuberculosis, multiple cysts, hydronephrotic transformation. An error in the diagnosis often causes unjustified surgery, for example, plastic surgery of the pelvic-ureteral segment, after which a number of complications are added. The tactics of examination of a patient diagnosed with megacalicosis include:
- Instrumental diagnostics. The first–line imaging study – ultrasound of the kidneys – locates large round-shaped cups with a normal pelvis, their number can reach 20-25. On urograms after excretory urography performed, there is a similar picture: several spherical shadows are visible in place of the malpighian pyramids, there is no renal dysfunction. Megacalicosis is also confirmed by magnetic resonance imaging and MSCT of the kidneys with contrast.
- Laboratory tests. General blood and urine tests may show an inflammatory process accompanying megacalicosis. Its severity is indicated by accelerated ESR, a shift of the leukocyte formula to the left. In the general analysis of urine, leukocyturia, hematuria, crystalluria are detected, which helps in the diagnosis of complications. The presence of bacteria in the urine, even with a normal number of white blood cells, is an indication for a culture study.
Differential diagnosis is carried out with urogenital tuberculosis, kidney cysts, hydronephrotic transformation. Papillary necrosis with X-ray examination methods has a similar picture with tubulomedullary dysplasia. With pyelonephritis, the cups are moderately expanded, rounded, and their necks are narrowed.
Treatment
The asymptomatic course of the anomaly does not require therapy. If concomitant pathology is detected (exacerbation of pyelonephritis, nephrolithiasis with impaired passage of urine), hospitalization in a urological or nephrological hospital is possible. The tactics of managing a patient with megacalicosis are as follows:
- Treatment of complications. Prescribe antibiotics, uroseptics, taking into account sensitivity, litholytic drugs for dissolving microliths. The patient is recommended to adhere to a diet with the exception of spicy, salty dishes, extractive broths. The elimination of pathogens is facilitated by an enhanced drinking regime, therefore, herbal preparations, decoctions of diuretic herbs are used for greater diuresis.
- Dynamic observation. Patients with megacalicosis are registered with a nephrologist, take tests 2 times a year (OAM, UAC, urea and creatinine), undergo ultrasound of the kidneys. According to the results of the examination, the doctor can send for inpatient treatment: conservative with exacerbation of concomitant pyelonephritis or operative – to remove the concretion from the kidney. Planned intervention is more often performed by minimally invasive methods – CT (contact ureterolithotripsy), remote nephrolithotripsy, etc.
Prognosis and prevention
The prognosis for life is favorable, since uncomplicated megacalicosis does not lead to impaired kidney function. The outcome of the combined pathology depends on the severity of the concomitant disease, the timeliness and adequacy of therapy, the state of the immune status. Preventive measures to prevent megacalicosis have not been developed, but it has been proven that the frequency of birth defects in children is higher if the mother abused alcohol, drugs or was exposed to any teratogenic effects during gestation. All patients with detected megacalicosis should be regularly monitored by specialized specialists for the prevention of complications and their treatment.