[Effect of a simple kidney cyst on renal function]

INTRODUCTION

Renal cysts are a common disease that occurs at a rate of 7-10%. Currently there are no clinical recommendations for the treatment of patients with simple renal cysts. In the current literature there is some evidence that a simple renal cyst has negative effects on renal function. Decreased renal function occurs due to partial atrophy and loss of the renal parenchyma (in the "crater" area at the base of the cyst) caused by compression. Therefore, the efforts to analyze the effect of simple kidney cysts on kidney function and identify the characteristics of the cyst that affect renal function to determine the indications for surgical treatment remains a substantial task. The aim of the study was to analyze the effect of simple renal cysts on renal function, to investigate the relationship between cyst size, atrophied parenchyma volume, and renal function, and to determine indications for surgical treatment of simple renal cysts.

MATERIALS AND METHODS

We conducted a prospective cohort study. The study included 109 patients with simple renal cysts. Patients with a solitary cyst of the right or left renal kidney, grade I-II according to Bosniak classification, were included in the study. The estimated glomerular filtration rate (eGFR) of the patients was calculated using various formulas. A contrast CT scan of the urinary tract was also performed to determine the maximum size of the cyst, calculate the volume of the renal parenchyma, and the volume of the lost (atrophied) parenchyma. Patients underwent renal scintigraphy with calculation of total GFR and split renal function. We analyzed the symmetry of the function of both kidneys by comparing the GFR of the affected and healthy kidneys, analyzed the relationship between the presence of a kidney cyst and a decrease in GFR, between the maximum size of a renal cyst and a decrease in its function compared with that of a healthy kidney. We also analyzed the correspondence of total GFR values obtained in renal scintigraphy and GFR values calculated according to the formulas.

RESULTS

Data from 109 patients were available for analysis; the mean blood creatinine was 87.4 mol/L. The median maximum cyst size was 80 mm. The median baseline volume of the affected kidney parenchyma was 174 ml, the median volume of the lost parenchyma was 49 ml, and the median proportion of the lost parenchyma was 28%. The median total GFR was 77.07 ml/min. The median GFR of the healthy kidney was 45.49 mL/min, and the median GFR of the kidney affected by the cyst was 34.46 mL/min. The median difference in GFR of the healthy and affected kidney units was 11 mL/min and was statistically significant. Comparison of the eGFR values obtained by the formulas with the reference values of GFR obtained by scintigraphy showed that the Cockcroft-Gault formula with standardization on the body surface area calculated closest eGFR values to the reference ones. Correlation analysis revealed a statistically significant association between the proportion of lost parenchyma volume and the maximum cyst size: =0.37 with 95% CI [0.20; 0.52] (p-value = 0). A multivariate logistic regression model revealed that a statistically significant factor influencing the probability of a significant decrease in GFR was the percent of lost renal parenchyma volume (OR=1,13; =0).

CONCLUSIONS

Our study showed that growth of renal cysts associated with renal parenchyma atrophy and decrease of GFR of the affected kidney. An increase in the volume of atrophied parenchyma leads to the decrease in GFR of the affected kidney. The obtained data suggest that performing dynamic renal scintigraphy to assess the decrease in affected renal function and determine the indications for surgical treatment of renal cysts is a reasonable recommendation. According to the results of the study, the loss of 20% of the renal parenchyma can be considered an indication for renal scintigraphy. The Cockcroft-Gault formula with standardization on the body surface area allows to calculate closest GFR values to those obtained by scintigraphy and, therefore, can be recommended as the optimal formula for calculating eGFR in daily clinical practice.

Simple renal cyst as an independent risk factor for hypertension

A simple renal cyst (SRC) may increase the risk for hypertension. The authors examined the relationship between a SRC and hypertension in participants receiving physical examinations at Hebei Medical University. This study enrolled 66 883 participants who received physical examinations at our center from January 2012 to December 2017. Demographic data, medical history related to hypertension, hematological indexes, hypertension, and SRC subtype based on ultrasound examinations were examined. The relationship between SRC and hypertension was analyzed using univariate and multivariate logistic regression analysis in different models. Subgroup analysis and propensity score (PS) matching were also performed. Based on SRC subtype (unitary vs. multiple, small vs. large, unilateral vs. bilateral), a comprehensive scoring system was established to determine the effect of SRC load on hypertension. The results of univariate and multivariate analysis indicated that SRC was a risk factor for hypertension (P < .01). Subgroup and interaction analysis showed the homogeneity that SRC was an independent risk factor for hypertension in multiple subgroups (P > .05). A SRC remained an independent risk factor for hypertension after PS matching (P < .01). Based on a scoring system that considered different SRC subtypes, the risk for hypertension increased with renal cyst load (P < .01). In conclusions, a SRC was an independent risk factor for hypertension, and there was a positive correlation between SRC load and hypertension. The risk of hypertension increased gradually with the size, number, and location of a SRC. Careful follow‐up or excision should be considered for patients with SRCs.

The Presence of Simple Renal Cysts Is Associated With Increased Arterial Stiffness in Patients With Abdominal Aortic Aneurysm

Simple renal cysts (SRC) are associated with the development of abdominal aortic aneurysms (AAA). We hypothesized that patients with AAA and SRC have increased arterial stiffness (AS) compared with patients without SRC. Patients (n=223) with an infrarenal AAA undergoing pulse wave analysis were recruited. Brachial-ankle pulse wave velocity (PWV) was measured (automated oscillometric method) as an index of AS. Participants were categorized into those with increased AS and those with normal/borderline AS (threshold: 1800 cm/s); 134 patients (60.1%) had increased AS and 89 (39.9%) patients had normal/borderline AS. Multivariable analyses showed that age ≥75 years (odds ratio [OR], 2.83; 95% confidence interval [CI], 1.51-5.72; P=.002), systolic blood pressure ≥140 mmHg (OR, 5.05; 95% CI, 2.35-10.83; P<.001), hypertension (OR, 2.28; 95% CI, 1.08-4.79; P=.030), and presence of SRC (OR, 1.89; 95% CI, 1.03-3.46; P=.040) were independent risk factors for increased AS. The presence of SRC is an independent risk factor for increased AS in patients with an AAA. This association suggests that patients with SRC may have severe aortic wall degeneration and thus the presence of SRC may be pathologically linked to the development of AAA.

Development and external validation of a nomogram for predicting renal function based on preoperative data from in-hospital patients with simple renal cysts

Objective

To develop and validate a nomogram for predicting renal dysfunction in patients with simple renal cysts (SRCs).

Methods

We performed a multivariable logistic regression analysis of an in-hospital retrospective cohort of patients with SRCs in the Urology Department of the First Affiliated Hospital of Anhui Medical University. For prognostic model development, 386 patients with SRCs were enrolled from January 2016 to December 2018. External validation was performed in 46 patients with SRCs from January 2019 to April 2019. The primary outcome was renal dysfunction.

Results

Patients were divided into normal or abnormal estimated glomerular filtration rate groups (293 vs. 93) based on the cut-off value of 90 mL/minute/1.73 m². Logistical regression analysis determined that age, haemoglobin, globulin, and creatinine might be associated with renal dysfunction, and a novel nomogram was established. Calibration curves showed that the true prediction rate was 77.42%, and decision curve analysis revealed that the nomogram was more effective with threshold probabilities ranging from 0.1 to 0.8. The area under the curves were 0.829, 0.752, and 0.888 in the overall training, internal, and external validation cohorts, respectively.

Conclusions

We established a nomogram to predict the probability of developing renal dysfunction in patients with SRCs.

A Case Report of Calyceal Diverticulum: Differential Diagnosis for Organ-Preserving Operations

Calyceal diverticula and epidermal cysts are extremely rare kidney lesions with unknown etiology and pathogenesis. They have non-specific clinical and radiological picture. Despite the benign nature, sometimes these disorders mimic malignant tumors leading to unjustified nephrectomy. We present a clinical and morphological observation of a multicystic lesion in a 76-year-old patient's right kidney filled with keratinized masses and imitating a malignant solid tumor. The detailed gross, histological and immunohistochemical (desmin, cytokeratin 7, uroplakin and p63) analyses of the kidney tissue excluded the malignant nature of the lesion. The final differential diagnosis was between an epidermal cyst and calyceal diverticulum with pronounced squamous cell metaplasia of urothelium. The upper pole localization of the lesion, its connection with the pelvicalyceal system through the unobstructed isthmus, the presence of urothelial lining and smooth muscle cells in its wall let us diagnose a calyceal diverticulum type I. Knowledge of the key clinical and morphological features of epidermal cysts and diverticula of the pelvicalyceal system will help the practicing physicians suspect the benign nature of such lesions and perform organ-preserving operations.

Partial nephrectomy for a Bosniak IV cystic renal mass mimicking a simple renal cyst adjacent to a solid renal tumor

INTRODUCTION

Renal tumors are often associated with renal cysts. Meanwhile, in some cases there are challenging issues of how to diagnose renal cystic tumors and to decide surgical procedures.

CASE PRESENTATION

A 75-year-old man was referred to our department for a 21-mm tumor by his left kidney. Contrast-enhanced computed tomography showed an intense contrast uptake the tumor, which was adjacent to a 64-mm unilocular renal cyst with no contrasting effects. It was clinically diagnosed as renal cell carcinoma, stage T1aN0M0, and treated with robot-assisted partial nephrectomy, for both the solid tumor and the adjacent cyst. Pathological findings revealed a tumor cell clump within the cyst wall, concurrent with the renal cell carcinoma. The patient has remained free of disease at 1 year after surgery.

CONCLUSION

A partial nephrectomy that includes the entire cyst wall should be considered for renal tumor associated with unilocular renal cyst.

The association between simple renal cyst and aortic diseases: A systematic review and meta-analysis of observational studies

OBJECTIVE

The objective of this meta-analysis of observational studies was to evaluate the association between simple renal cysts (SRC) and presence of aortic pathology such as aortic aneurysms and dissection.

METHODS

We conducted searches in Ovid MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials from January 1960 to August 2019 to identify observational studies that examined the association between SRCs and any aortic diseases, including aortic aneurysms and dissection. Two reviewers independently extracted the data and assessed the risk of bias. The meta-analysis was performed by STATA 14.1.

RESULTS

In total, 11 observational studies with 19 719 participants were included in this meta-analysis. Compared to individuals without SRCs, patients with SRCs had higher odds of abdominal aortic aneurysm (AAA) (adjusted OR = 2.61, 95% CI 2.34-2.91, P < 0.001, I²   = 0%), ascending thoracic aortic aneurysm (TAA) (adjusted OR = 1.98, 95% CI 1.09-3.63, P = 0.03, I²   = 90.1%), descending TAA (adjusted OR = 3.44, 95% CI, 2.67-4.43, P < 0.001, I²   = 0%), type A aortic dissection (AD) (adjusted OR = 1.98, 95% CI 1.32-2.96, P = 0.001, I²   = 12.9%), and type B AD (adjusted OR = 2.55, 95% CI, 1.31-4.96, P = 0.006, I²   = 76.2%). There was a higher average in the sum of diameter of SRCs among AAA compared to patients without AAA (WMD = 19.80 mm, 95% CI 13.92-25.67, P < 0.001, I²   = 63.8%).

CONCLUSION

SRC is associated with higher odds of aortic diseases including AAA, ascending and descending TAA, type A and type B dissection even after adjusting for confounders.

A Comparative Study of Percutaneous Aspiration with Sclerotherapy and Laparoscopic Marsupialization for Symptomatic Simple Renal Cysts

Background: Percutaneous aspiration with sclerotherapy (PAS) and laparoscopic marsupialization (LM) are minimally invasive treatment modalities for renal cysts. We aimed to compare the efficacy and cost/effectiveness of LM and PAS for the treatment of simple symptomatic renal cysts. Methods: Data were prospectively collected from three health care institutions in which 80 patients with symptomatic simple renal cysts underwent a single session of PAS with 95% ethanol (PAS group, n = 40) or underwent LM under general anesthesia (LM group, n = 40) between March 2012 and May 2016. We compared the patient profile, duration of procedure, duration of hospital stay, radiological and symptomatic success rates, treatment costs, and incidence of complications between the two groups. Results: At the 6-month follow-up, the radiological success rate in the LM group was significantly greater than that in the PAS group (97.5% versus 60%; P < .001). The symptomatic success rate was comparable in the two groups (95% versus 90%; P = .675). The treatment failure rate did not significantly differ between the two groups (5.0% versus 17.5%, P = .154). The mean total cost in the PAS and LM groups was 1256 USD and 2343 USD, respectively (P = .001). No significant between-group difference was noted regarding the overall complication rate (P = .615). Conclusions: Both LM and PAS are effective and safe procedures for the treatment of symptomatic simple renal cysts. A single session of PAS seems to be a cost-effective method for the management of symptomatic simple renal cysts.

Endothelin-1 Level in Patients with Simple Renal Cyst

INTRODUCTION

Endothelin-1 (ET-1) is potent vasoconstrictive peptide and elevated ET-1 levels are associated with hypertension, endothelial dysfunction and atherosclerosis. Research on (ET-1) has demonstrated that elevated ET-1 levels in autosomal dominant polycystic kidney disease leads to systemic hypertension. The prevalence of simple renal cysts increases with age and the association with simple renal cyst and hypertension is not clear. The aim of this study was to investigate the ET-1 levels in patients with simple renal cyst and compare them with those in healthy adults.

MATERIALS AND METHODS

The study included patients that underwent laparoscopic renal cyst decortication in the Department of Urology and healthy controls. Serum and urinary ET-1 levels were measured before surgery and one month after it in the patients with simple renal cyst. Serum ET-1 levels were measured in healthy adult patients. Ambulatory blood pressure was measured in all patients. Glomerular filtration rate was measured according to the chronic kidney disease epidemiology collaboration formula.

RESULTS

Thirty-two patients were included in the present study. Of these, 16 patients with simple renal cyst were allocated into group 1 and 16 healthy patients - in group 2. There was no significant difference between systolic and diastolic blood pressure between the groups (.

CONCLUSIONS

The present study demonstrated that serum EL-1 level in patients with simple renal cyst was lower than that in healthy people. Further studies are needed to investigate the EL-1 levels in simple renal cyst patients.

Renal cell carcinoma originating in the free wall of simple renal cyst: Two unusual case reports with literature review

RATIONALE

Simple renal cyst (SRC) is a benign disease. However, rarely renal cell carcinoma (RCC) may be raised at the wall of a preexisting SRC. We herein describe 2 unusual cases of RCC arising from the outer surface of the free wall of the renal cyst.

PATIENT CONCERNS

A 75-year-old female and a male were admitted to our department because of an asymptomatic renal cystic mass. Although the case history, preoperative imaging, and intraoperative examination of the cyst were carefully evaluated, no concerns were raised with respect to the underlying malignancy.

DIAGNOSIS

RCC of the clear cell type was diagnosed based on the histology and pathological examination.

INTERVENTIONS

With an initial diagnosis of SRC, the retroperitoneal laparoscopic de-roofing of the SRC was performed in both of the patients. When the diagnoses were confirmed 7 days postoperative, both of them were readmitted to our department for a radical nephroureterectomy.

OUTCOMES

The postoperative course was uneventful and the two patients did not undergo further chemotherapy. They are currently well and have no clinical or radiological signs of recurrence.

LESSONS

Such cases remind us that seemingly benign renal cysts may harbor underlying neoplasia. Further evaluation and periodical follow-up are also recommended on the management of those seemingly benign renal cysts.

The efficacy of retroperitoneal laparoscopic deroofing of simple renal cyst with perirenal fat tissue wadding technique: A retrospective study

Treatment options for simple renal cyst (SRC) include open surgery, laparoscopy with decortication, or percutaneous aspiration with or without sclerotherapy. Though laparoscopic unroofing achieves better results than percutaneous sclerotherapy, the reported recurrence rate is still up to 19%. Thus, it is necessary to find methods to reduce the recurrence rate.To investigate whether the perirenal pedicled fat tissue wadding technique during retroperitoneal laproscopic deroofing (RLD) of SRC affects the incidence of recurrence.A retrospective analysis was carried out on clinical data of 254 patients with SRC treated by RLD in our hospital from 2008 to 2016. Among these patients,119 had a simple retroperitoneal deroofing (SRD) and 135 received a retroperitoneoscopic deroofing with wadding of the cyst using perirenal fat tissue (RDCW). The recurrence rate and variables, as well as perioperative complications, were compared. To further explore the potential variables influencing cyst recurrence rate, univariate and multivariate regression analyses were applied.A total of 251 patients were included in the analysis. The operation was successfully completed laparoscopically in all cases with no conversion to open surgery. No mortality or significant complication occurred in both groups. After a median follow-up of 38.67 months, we noted 41 recurrences. According to the univariate and multivariate regression analyses, patients managed with the wadding technique had superior recurrence-free survival (RFS), compared with patients in SRD group (log-rank P = .03 and P = .04, respectively). Moreover, patients with single renal cyst had a lower recurrence rate, compared with patients with multiple renal cysts (log-rank P < .01). Regarding the operation time, blood loss, and hospital stay, no statistically significant difference was found between 2 groups (P values .13, .30, and .75, respectively). However, less postoperative drainage and shorter postoperative interval until tube removal (P = .04) were observed in RDCW group.The perirenal pedicled fat tissue wadding technique can decrease the cyst recurrence rate and RCDW represents an effective and safe treatment option in the management of renal cysts.

Beware! A simple renal cyst could be a hydatid cyst

Kidney is one of the most common sites for the cyst formation in the body, and the management of simple cysts is required entirely for its symptoms and complications. Surgical decortication is an established treatment for a large and symptomatic simple renal cyst. On the other hand, hydatid cysts of the kidney are usually multiloculated complex or calcified cysts and are quite rare. Their surgical treatment also differs and requires complete excision with pericystectomy or partial/complete nephrectomy depending upon residual functional parenchyma, using extreme caution to avoid spillage, recurrence or development of severe anaphylactic shock. A simple cyst harboring a hydatid cyst is highly uncommon and quite dangerous; as if not diagnosed preoperatively, it can create huge trouble for both the patient and the operating surgeon which happened in the present case.

Renal cell carcinoma presenting as a simple renal cyst: A case report

Cases of renal cell carcinoma (RCC) presenting as a simple cyst are extremely rare. We herein report the case of a patient with RCC diagnosed as a simple renal cyst preoperatively. A 39-year-old female patient presented with abdominal pain for 3 months. Ultrasonography and contrast-enhanced computed tomography revealed a simple cyst in the left kidney. The patient underwent laparoscopic decortication of the renal cyst. Biochemical analysis of the cystic fluid revealed unusually low levels of potassium, sodium, calcium and glucose, and the histological examination of the floor of the cyst indicated malignancy. Laparoscopic nephrectomy was performed 20 days later and the pathological examination confirmed the diagnosis of RCC of the clear cell type. At the 2-year follow-up, the patient remained well and recurrence-free on imaging. The aim of the present study was to emphasize the importance of recognizing that RCC may occur in what appears to be a simple renal cyst based on imaging results. Biochemical analysis of the cystic fluid may help identify the presence of malignancy.

Simple Renal Cysts as Markers of Thoracic Aortic Disease

Background

Thoracic aortic aneurysm is usually a clinically silent disease; timely detection is largely dependent upon identification of clinical markers of thoracic aortic disease (TAD); (bicuspid aortic valve, intracranial aortic aneurysm, bovine aortic arch, or positive family history). Recently, an association of simple renal cysts (SRC) with abdominal aortic aneurysm and aortic dissection was established. The aim of our study was to evaluate the prevalence of SRC in patients with TAD in order to assess whether the presence of SRC can be used as a predictor of TAD.

Methods and Results

We evaluated the prevalence of SRC in 842 patients with TAD (64.0% males) treated at our institution from 2004 to 2013 and compared to a control group of patients (n=543; 56.2% males). Patients were divided into 4 groups: ascending aortic aneurysm (456; 54.2%); descending aortic aneurysm (86; 10.2%); type A aortic dissection (118; 14.0%); and type B aortic dissection (182; 21.6%). SRC were identified by abdominal computed tomography or magnetic resonance imaging of these patients. Prevalence of SRC is 37.5%, 57.0%, 44.1%, and 47.3% for patients with ascending aneurysm, descending aneurysm, type A dissection, and type B dissection, respectively. Prevalence of SRC in the control group was 15.3%. Prevalence of SRC was not significantly different between male and female aortic disease patients, despite reported general male predominance (2:1), which was also observed in our control group (1.7:1).

Conclusions

This study establishes an increased prevalence of SRC in patients with TAD. SRC can potentially be used as a marker for timely detection of patients at risk of TAD.

Current state and effectiveness of abdominal ultrasonography in complete medical screening

PURPOSE

The current state and effectiveness of abdominal ultrasonography (US) were investigated by reviewing statistical data for US of the kidney as part of complete medical screenings conducted at our institution between April 1994 and March 2004.

METHODS

Among 4339 individuals with US findings, computed tomography (CT) was performed on 129 individuals at our institution. Among these individuals, US findings and CT diagnoses were compared and analyzed.

RESULTS

US findings indicated renal tumors in 73 of the 129 subjects, and the breakdown of CT diagnoses for these 73 individuals was as follows: no lesion, n = 45 (61.6%); simple renal cyst, n = 13 (17.8%); complicated renal cyst, n = 5 (6.8%); suspected malignant tumor, n = 5 (6.8%); renal angiomyolipoma, n = 2 (2.7%); pelvic dilatation, n = 1 (1.4%); granuloma, n = 1 (1.4%); teratoma, n = 1 (1.4%). Magnetic resonance imaging (MRI) was performed on 4 of the 5 subjects with suspected malignant tumor, and surgery was performed in all 4 cases with suspected kidney cancer. Kidney cancer was histopathologically confirmed in 2 patients, resulting in a detection rate of 0.046% for kidney cancer by US as part of a complete medical screening. In the 2 patients with kidney cancer, differentiating cystic renal cell cancer from a renal cyst was not possible based on US findings alone in 1 patient, and no thorough examinations were performed in the 3 years leading up to surgery.

CONCLUSIONS

These results suggest that additional US and thorough examinations are necessary if a lesion cannot be confirmed as a simple renal cyst on initial US. Furthermore, to improve the skill levels of healthcare professionals who perform and interpret US, a feedback system should be established where data related to complete medical screenings are available to the personnel involved.