Retrograde vs. antegrade flexible nephroscopy for detection of residual fragments following PNL: a prospective study with computerized tomography control

ABSTRACT Introduction: The main aim of stone surgery is to establish stone free status. Performing flexible nephroscopy is an effective tool in this manner. The aim of this study was to evaluate the role of retrograde flexible nephroscopy for detection of residual fragments following percutaneous nephrolithotomy (PNL) in comparison with antegrade approach. Materials and Methods: Data of 137 patients underwent ECIRS was collected prospectively. In all cases following stone clearance, collecting system was checked for residual fragments. First antegrade than retrograde flexible nephroscopy was performed and success rates to reach all calices and detection of residual fragments were noted. All patients underwent CT and success rate of antegrade and retrograde approaches were compared. PPV and NPV of retrograde approach to detect residual fragments were calculated. Results: Antegrade and retrograde nephroscopy successfully accessed all of the calices in 101 (73.7%) and 130 (94.9%) patients respectively (p<0.0001). Residual fragments were observed in 18 (13.1%) patients following antegrade flexible nephroscopy. Retrograde approach identified residual stones in 17 more cases. These cases were treated with flexible nephroscopy or secondary percutaneous tract. Postoperative CT revealed residual stones in 10 (7.3%) patients. PPV and NPV of retrograde flexible nephroscopy were 83.3% and 96.2%. Conclusions: Flexible nephroscopy effectively detects residual fragments following PNL. Retrograde approach was more successful than antegrade approach to reach all calices. We recommend performing retrograde flexible nephroscopy following PNL especially in complex cases as it has the potential to increase SFR, decrease the need for second look surgery and unnecessary postoperative imaging.

Divertículo calicial y su diagnóstico incidental / Calyceal diverticulum and its incidental diagnosis

Introducción: El divérticulo calicial se detecta en 0,21 a 0.60 por ciento de los urogramas excretores. Objetivos: Describir una paciente con diagnóstico incidental de esta anomalía y su seguimiento durante 11 años. Presentación del caso: Durante la realización de un urograma excretor para el estudio de una hidronefrosis en una niña de siete años de edad, se detectó un divertículo calicial en el riñón contralateral y después de 11 años de seguimiento ultrasonográfico no se ha demostrado modificación ni complicación del divertículo. Conclusiones: El divertículo calicial es una anomalía congénita que puede mantenerse sin complicaciones durante años por lo que debe tratarse conservadoramente(AU)

ABSTRACT Introduction: Calyceal diverticulum is detected in 0,21 percent to 0.60 percent of excretory urogram. Objectives: To describe a patient with an incidental diagnosis of this anomaly and her follow up during 11 years. Case presentation: During the performance of an excretory urogram for studying a hydronefrosis in a seven years old girl, a calyceal diverticulum was detected in the contralateral kidney; and after 11 years of ultrasonographic follow-up there has been no modifications or complication related with the diverticulum. Conclusions: Calycial diverticulum is a congenital anomaly that can last years without presenting complications. That is why it must be treated conservatively(AU)

Skin to calyx distance is not a predictive factor for miniaturized percutaneous nephrolithotomy outcomes

ABSTRACT Objective To evaluate the predictive value of the distance from skin to calyx (SCD) on the outcome and complication rates of patients undergoing mPNL. Materials and Methods Patient's charts, who had undergone mPNL between June 2012 and June 2015, were analyzed retrospectively. Patients who had a preoperative computerized tomography (CT) were enrolled into the study. Two separateurologists evaluated the CT scans and calculated the SCD defined as the distance between the skin and surface/lateral edge of the calyx, which was the preferred site of entry for percutaneous access. The average value of the two measurements was included inthe final analysis to avoid bias. The mean SCD was 75mm. According to the median SCD value, patients were divided into two groups: group 1 (SCD ≤75) and group 2 (SCD >75). Results A total of 140 patients and 130 patients were enrolled in groups 1 and 2, respectively. The mean operation time and the mean fluoroscopy time was significantly longer in group 2 (p:0.004 vs. p:0.021). The rate of blood transfusion was significantly higher in group 1 (6 patients). None of patientsin group 2required blood transfusion (p:0.017). Stone-free status after a single session of mPNL was 67.1% in group 1 and 75.4% in group 2 (p:0.112). After additional procedures, stone-free rates increased to 84.3% and 85.4% in group 1 and group 2, respectively (p:0.802). Conclusion Our study demonstrated that longer SCD was not a predictive factor for stone-free rates after mPNL. However, SCD over 75mm was associated with longer operation time and fluoroscopy time with lower rates of transfusion.

Analysis of the Skin to Calyceal Distance (SCD) to the upper pole calyx among Filipino patients: A guide to upper pole access Percutaneous Nephrolithotomy (PCNL)

OBJECTIVE: Precise entry to the upper posterior calyx is key to a successful and safe upper pole access PCNL. The surgeon's knowledge of the average skin to calyceal distance can serve as a guide to avoid inadvertent injury to both the kidney and collateral organs during the percutaneous puncture.METHODS: The authors analyzed the radiologic images of 84 patients who underwent unenhanced 64-slice helical CT scan (Toshiba®). Skin-to-calyceal distance (SCD) to the upper posterior calyx were measured using the Vitrea® software inherent to the CT scan.RESULTS: The mean SCDs is non-hydronephrotic kidneys were 54.9 ± 13.7 mm and 61.4 ± 12.5 mm on the right and left, respectively while in hydronephrotic kidneys, the mean SCDs were 60.3 ± 11.8 mm and 58.6 ± 13.1 mm on the right and left, respectively. There was no statistically significant difference between the right and left upper pole SCD in both groups (p = 0.84).CONCLUSION: The mean SCD to the upper posterior calyx among Filipino adults is about 6.0 cm. By limiting the depth of the initial puncture to within the distance, the endourologist may avoid overshooting the targeted calyx, thus avoiding undue injury to the kidney or intraabdominal structures.

Comparative analysis on the efficacy and safety profile of upper calyceal versus lower calyceal access in the percutaneous nephrolithotomy (PCNL): A retrospective cross-sectional study

INTRODUCTION: The goal of PCNL is to achieve a high stone-free rate while minimizing complications. Its success results from an interplay of patient, stone and renal anatomical characteristics, the access site and the level of surgical expertise. Data comparing upper versus lower calyceal PCNL as regard to efficacy and safety are limited.OBJECTIVE: To compare the clinical efficacy and safety outcomes of upper versus lower calyceal access in patients who underwent PCNL at St. Luke's Medical Center.METHODS: A retrospective chart review was done on patients who underwent PCNL at SLMC from January 2010-January 2015. The patients were classified based on the renal access site: Group 1 (upper calyceal) and Group 2 (lower calyceal). The stones were classified according to Guy Stone score and complications were summarized using the modified Clavien classification.RESULTS: A total pf 91 patients underwent PCNL during the study period. Of these, only 84 patients were analyzed. Seven were excluded due to lack or incomplete postoperative imaging on follow up. Forty-one were included in Group 1, while 43 were included in Group 2. According to the Guy Stone score, the stones in Group 1 were 21(IV), 6(III), 7(II) and 6(I) while in Group 2, 18(IV), 5(III), 8(II), 12(I) (p-value=0.52) with a mean stone volume of 38.2± 44.24cm3 and 28.0± 31.04cm3 in Groups 1 and 2 respectively (p-value= 0.23). Success rate was 80.5% and 83.7% for Groups 1 and 2 (p-value=0.70), respectively and mean stone clearance rates of 98.5% and 95.8% (p-value=0.13),respectively. The mean operative time was 181.0±82.26 and 169.5±52.12mins for Groups 1 and 2 (p-value=0.451),respectively. A total of 36 complications (13 from Group 1 and 23 from Group 2) were evaluated. Fever (Grade 1) occurred in 10 (24%) and 17(39%) for Groups 1 and 2, respectively. Blood transfusion (Grade 2) was observed in 4(9%) patients and 3(7%) in Groups 1 and 2, respectively. Two patients (5%) in Group 2 required postoperative double-J sent insertion due to ureteral stone migration (Grade 3). There was no significant difference noted among the groups as regards complication rates (p-value=0.097) and length of hospital stay (p-value=0.687). There was no mortality in either group.CONCLUSION: Based on our experience, both upper and lower calyceal access PCNL achieve equivalent efficacy and comparable safety profile in the treatment of complex renal stones.

The clinical safety and efficacy of upper pole access percutaneous nephrolithotomy (uPPCNL) for inferior pole stones

@#<p style="text-align: justify;"><strong>OBJECTIVE:</strong> Traditionally, percutaneous nephrolithotomy (PCNL) for a lower pole stones are directly removed through an inferior polar access. The authors preferentially treated inferior pole calculi with an upper polar access and evaluated the clinical outcomes.<br /><strong>METHODS:</strong> Between January 2010 and April 2016, 32 patients with inferior calyceal stones were treated uPPCNL. All stones were diagnosed using an unenhanced CT scan. The efficacy (stone-free rate) was determined by comparing the preoperative and postoperative imaging. Clinical safety was assessed based on intraoperative parameters pertaining to operative time, blood loss, urinary extravasation, calyceal injury, pelvic perforation and other untoward events. These complications were summarized using the Clavien-Dindo grading system.<br /><strong>RESULTS:</strong> The male to female ratio is 1.1:1. All stones included in the study were pure inferior calyceal in location. The average stone size was 1.65±0.84cm (Range:0.6-4.4) with a mean durility of 936±298HU (Range: 350-1500). Stone-free rate was 96.8% (31/32) after a single session of PCNL. The mean operative time was 97±43 minutes (Range:40-230). According to the Clavien-Dindo classification, 26(81.3%) had no complication, 5 (15.6%) had Grade 1 (fever), and 1 (3.1%) had Grade 2.<br /><strong>CONCLUSION:</strong> uPPCNL is effective and safe for patients with inferior calyceal stones and confers the following advantages 1) shorter skin-to-calyceal distance 2) straight line to the UPJ and inferior pole 3) a panoramic view of the collecting system 4) less stone migration 5) minimal torque of the nephroscope. This minimally invasive procedure achieves a high stone clearance rate with acceptably low complication rates.</p>

Analysis of the Skin to Calyceal Distance (SCD) to the upper pole calyx among Filipino patients: A guide to upper pole access Percutaneous Nephrolithotomy (PCNL)

@#<p style="text-align: justify;"><strong>OBJECTIVE:</strong> Precise entry to the upper posterior calyx is key to a successful and safe upper pole access PCNL. The surgeon's knowledge of the average skin to calyceal distance can serve as a guide to avoid inadvertent injury to both the kidney and collateral organs during the percutaneous puncture.<br /><strong>METHODS:</strong> The authors analyzed the radiologic images of 84 patients who underwent unenhanced 64-slice helical CT scan (Toshiba®). Skin-to-calyceal distance (SCD) to the upper posterior calyx were measured using the Vitrea® software inherent to the CT scan.<br /><strong>RESULTS:</strong> The mean SCDs is non-hydronephrotic kidneys were 54.9 ± 13.7 mm and 61.4 ± 12.5 mm on the right and left, respectively while in hydronephrotic kidneys, the mean SCDs were 60.3 ± 11.8 mm and 58.6 ± 13.1 mm on the right and left, respectively. There was no statistically significant difference between the right and left upper pole SCD in both groups (p = 0.84).<br /><strong>CONCLUSION:</strong> The mean SCD to the upper posterior calyx among Filipino adults is about 6.0 cm. By limiting the depth of the initial puncture to within the distance, the endourologist may avoid overshooting the targeted calyx, thus avoiding undue injury to the kidney or intraabdominal structures.</p>

Comparative analysis of the efficacy and safety profile of upper calyceal versus lower calyceal access in the percutaneous nephrolithotomy (PCNL): A retrospective cross-sectional study

@#<p style="text-align: justify;"><strong>INTRODUCTION:</strong> The goal of PCNL is to achieve a high stone-free rate while minimizing complications. Its success results from an interplay of patient, stone and renal anatomical characteristics, the access site and the level of surgical expertise. Data comparing upper versus lower calyceal PCNL as regard to efficacy and safety are limited.<br /><strong>OBJECTIVE:</strong> To compare the clinical efficacy and safety outcomes of upper versus lower calyceal access in patients who underwent PCNL at St. Luke's Medical Center.<br /><strong>METHODS:</strong> A retrospective chart review was done on patients who underwent PCNL at SLMC from January 2010-January 2015. The patients were classified based on the renal access site: Group 1 (upper calyceal) and Group 2 (lower calyceal). The stones were classified according to Guy Stone score and complications were summarized using the modified Clavien classification.<br /><strong>RESULTS:</strong> A total pf 91 patients underwent PCNL during the study period. Of these, only 84 patients were analyzed. Seven were excluded due to lack or incomplete postoperative imaging on follow up. Forty-one were included in Group 1, while 43 were included in Group 2. According to the Guy Stone score, the stones in Group 1 were 21(IV), 6(III), 7(II) and 6(I) while in Group 2, 18(IV), 5(III), 8(II), 12(I) (p-value=0.52) with a mean stone volume of 38.2± 44.24cm3 and 28.0± 31.04cm3 in Groups 1 and 2 respectively (p-value= 0.23). Success rate was 80.5% and 83.7% for Groups 1 and 2 (p-value=0.70), respectively and mean stone clearance rates of 98.5% and 95.8% (p-value=0.13),respectively. The mean operative time was 181.0±82.26 and 169.5±52.12mins for Groups 1 and 2 (p-value=0.451),respectively. A total of 36 complications (13 from Group 1 and 23 from Group 2) were evaluated. Fever (Grade 1) occurred in 10 (24%) and 17(39%) for Groups 1 and 2, respectively. Blood transfusion (Grade 2) was observed in 4(9%) patients and 3(7%) in Groups 1 and 2, respectively. Two patients (5%) in Group 2 required postoperative double-J sent insertion due to ureteral stone migration (Grade 3). There was no significant difference noted among the groups as regards complication rates (p-value=0.097) and length of hospital stay (p-value=0.687). There was no mortality in either group.<br /><strong>CONCLUSION:</strong> Based on our experience, both upper and lower calyceal access PCNL achieve equivalent efficacy and comparable safety profile in the treatment of complex renal stones.</p>

The clinical safety and efficacy of upper pole access percutaneous nephrolithotomy (uPPCNL) for inferior pole stones

OBJECTIVE: Traditionally, percutaneous nephrolithotomy (PCNL) for a lower pole stones are directly removed through an inferior polar access. The authors preferentially treated inferior pole calculi with an upper polar access and evaluated the clinical outcomes.METHODS: Between January 2010 and April 2016, 32 patients with inferior calyceal stones were treated uPPCNL. All stones were diagnosed using an unenhanced CT scan. The efficacy (stone-free rate) was determined by comparing the preoperative and postoperative imaging. Clinical safety was assessed based on intraoperative parameters pertaining to operative time, blood loss, urinary extravasation, calyceal injury, pelvic perforation and other untoward events. These complications were summarized using the Clavien-Dindo grading system.RESULTS: The male to female ratio is 1.1:1. All stones included in the study were pure inferior calyceal in location. The average stone size was 1.65±0.84cm (Range:0.6-4.4) with a mean durility of 936±298HU (Range: 350-1500). Stone-free rate was 96.8% (31/32) after a single session of PCNL. The mean operative time was 97±43 minutes (Range:40-230). According to the Clavien-Dindo classification, 26(81.3%) had no complication, 5 (15.6%) had Grade 1 (fever), and 1 (3.1%) had Grade 2.CONCLUSION: uPPCNL is effective and safe for patients with inferior calyceal stones and confers the following advantages 1) shorter skin-to-calyceal distance 2) straight line to the UPJ and inferior pole 3) a panoramic view of the collecting system 4) less stone migration 5) minimal torque of the nephroscope. This minimally invasive procedure achieves a high stone clearance rate with acceptably low complication rates.

Ureterocalycostomy - final resort in the management of secondary pelvi-ureteric junction obstruction: our experience

ABSTRACT: Ureterocalycostomy can be performed in patients in whom desired methods of treating secondary PUJ (Pelvi-Ureteric Junction) obstructions either failed or could not be used. In our study, one child and two adults in whom one redo-ureterocalycostomy and two ureterocalycostomies were performed for severely scarred PUJ. The causes for secondary PUJ obstruction were post-pyelolithotomy in one case, post-pyeloplasty and ureterocalycostomy for PUJ obstruction in the second patient and the third patient had long upper ureteric stricture post-ureteropyeloplasty due to tuberculosis. In all these cases ureterocalycostomy proved to be salvage/final resort for preserving functional renal unit

A Novel method of ensuring safe and accurate dilatation during percutaneous nephrolithotomy

ABSTRACT Objective: To report our technique that helps locate the guidewire into the ureter enabling safe dilatation during PCNL. Materials and Methods: Cases in which the guidewire failed to pass into the ureter following successful puncture of the desired calyx were subjected to this technique. A second guidewire was passed through the outer sheath of a 9 Fr. metallic dilator cannula, passed over the first guidewire. The cannula and outer sheath were removed, followed by percutaneous passage of a 6/7.5 Fr ureteroscope between the two guidewires, monitoring its progress through both the endoscopic and fluoroscopic monitors. Once the stone was visualized in the calyx a guidewire was passed through the working channel and maneuvered past the stone into the pelvis and ureter under direct endoscopic vision. This was followed by routine tract dilatation. Results: This technique was employed in 85 out of 675 cases of PCNL carried out at our institute between Jan 2010 to June 2014. The mean time required for our technique, calculated from the point of introduction of the ureteroscope untill the successful passage of the guidewire down into the ureter was 95 seconds. There were no intraoperative or postoperative complications as a result of this technique. Guidewire could be successfully passed into the ureter in 82 out of 85 cases. Conclusions: Use of the ureteroscope introduced percutaneously through the puncture site in PCNL, is a safe and effective technique that helps in maneuvering the guidewire down into the ureter, which subsequently enables safe dilatation.

Percutaneous puncture of renal calyxes guided by a novel device coupled with ultrasound

ABSTRACT Purpose: To evaluate the efficiency of a novel device coupled with ultrassound for renal percutaneous puncture. Materials and Methods: After establishing hydronephrosis, ten pigs had three calyxes of each kidney punctured by the same urology resident, with and without the new device ("Punctiometer"). Time for procedure completion, number of attempts to reach the calyx, puncture precision and puncture complications were recorded in both groups and compared. Results: Puncture success on the first attempt was achieved in 25 punctures (83%) with the Punctiometer and in 13 punctures (43%) without the Punctiometer (p=0.011). The mean time required to perform three punctures in each kidney was 14.5 minutes with the Punctiometer and 22.4 minutes without the Punctiometer (p=0.025). The only complications noted were renal hematomas. In the Punctiometer group, all kidneys had small hematomas. In the no Punctiometer group 80% had small hematomas, 10% had a medium hematoma and 10% had a big hematoma. There was no difference in complications between both groups. Conclusions: The Punctiometer is an effective device to increase the likelihood of an accurate renal calyx puncture during PCNL, with a shorter time required to perform the procedure.

Ultrasound evaluation of obstructive uropathy and its hemodynamic responses in southwest Nigeria

To determine the renal arterial hemodynamic changes induced by obstructive uropathy using Doppler ultrasonography.

Alpha adrenergic receptors in renal pelvis and calyces: can rat models be used?

We aimed, in this study, to determine the distribution of α-1 AR subtypes in rat and human pelvis and calyces, and to evaluate, by comparing these two species, the possibility of rats to be used as models for humans. Twenty patients with renal carcinoma were included into the study. The patients underwent radical nephrectomy for renal cell carcinoma (RCC). After nephrectomy, specimens were evaluated and excisional biopsies from healthy pelvis and calyces tissues were performed. When pathology confirmed the non-invasion of RCC, specimen was included into the study. A total of 7 adult Wistar Albino (250-300 g) female rats were used in this study. Specimens included renal pelvis and calyces. All specimens were evaluated under light microscope histopathologically. The concentrations of the receptor densities did not differ between the two groups. With the demonstration of the α receptors in rat kidneys and calyces, many receptor-based studies concerning both humans and rats can take place. Novel medication targeting these subtypes -in this matter α1A and α1D for renal pelvis and calyces- may be helpful for expulsive therapy and/or pain relief. With the demonstration of similar receptor densities between human and rat tissues, rat model may be useful for α-receptor trials for renal pelvis and calyces.

The skin-to-calyx distance measured by renal ct scan and ultrasound

PurposeWe developed a stereotactic device to guide the puncture for percutaneous nephrolithotripsy, which uses the distance from the target calyx to its perpendicular point on skin (SCD) to calculate the needle´s entry angle. This study seeks to validate the use of measurements obtained by ultrasound (US) and computerized tomography (CT) for needle´s entry angle calculation and to study factors that may interfere in this procedure.Materials and MethodsHeight, weight, abdominal circumference, CT of the urinary tract in dorsal decubitus (DD) and ventral decubitus (VD), and US of the kidneys in VD were obtained from thirty-five renal calculi patients. SCD obtained were compared and correlated with body-mass index (BMI).ResultsBMI was 28.66 ± 4.6 Kg/m2. SCD on CT in DD was 8.40 ± 2.06cm, in VD was 8.32 ± 1.95cm, in US was 6.74 ± 1.68cm. SCD measured by US and CT were statistically different (p < 0.001), whereas between CT in DD and VD were not. SCD of the lower calyx presented moderate correlation with BMI.ConclusionSCD obtained by CT in ventral and dorsal decubitus may be used for calculation of the needle´s entry angle. SCD obtained by US cannot be used. A rule for the correlation between BMI and the SCD could not be determined.

Técnica combinada de LEC con ureteroscopía flexible en cálculo de gran tamaño en cáliz inferior / ESWL technique combined with Flexible ureteroscopy in big lower calyx stones

El tratamiento del cálculo del caliz inferior es controversial. Los resultados del tratamiento de los cálculos caliciarios mayores de 1 cm especialmente en el cáliz inferior son no óptimos con la Litotripsia extracorpórea . Debido al avance en los ureteroscopios flexibles es que iniciamos una experiencia para obtener pacientes libres de cálculos residuales. Se presentan 15 pacientes con cálculos mayores de 1 cm. que fueron operados en una sola sesión aplicando primero Litotripsia extracorpórea hasta fragmentar el cálculo y luego extraer los fragmentos residuales con ureteroscopio flexible. En 14 de 15 pacientes el control demostró ausencia de caculos residuales. Esta experiencia demuestra la eficacia de la combinación de ambos métodos sin complicaciones. Debe evaluarse la relación costo beneficio de esta técnica en el objetivo de dejar a los pacientes libres de cálculos.

Treatment of lower caliz’ Stone is controversial. Greater than 1 cm and especially in the low caliz witht he extracorporeal lithotripsy is bad. Because of advances in flexible ureteroscopes is to begin an experience for patients with big stones in the low caliz. We present 15 patients with stones larger than 1 cm who were operated in a single session using extracorporeal lithotripsy to fragment first calculating and then extract the residual fragments with ureteroscoip flexible. In 14 of 15 patients showed Stone free. This report demonstrates the effectiveness of the combination of both methods without complications. Must evaluate the cost benefit of this technique in order to make patients stone free.

Predicting calyceal access for percutaneous nephrolithotomy with computed tomography multiplanar reconstruction

OBJECTIVES: Objective parameters in computed tomography (CT) scans that could predict calyceal access during percutaneous nephrolithotomy have not been evaluated. These parameters could improve access planning for percutaneous nephrolithotomy. We aimed to determine which parameters extracted from a preoperative multiplanar reconstructed CT could predict renal calyceal access during a percutaneous nephrolithotomy. METHODS: From January 2009 through April 2011, 230 patients underwent 284 percutaneous nephrolithotomies at our institution. Sixteen patients presented with complete staghorn calculi, and 11 patients (13 renal units) were analyzed. Five parameters were extracted from a preoperative reconstructed CT and compared with the surgical results of percutaneous nephrolithotomy. RESULTS: Fifty-eight calyces were studied, with an average of 4.4 calyces per procedure. A rigid nephroscope was used to access a particular calyx, and a univariate analysis showed that the entrance calyx had a smaller length (2.7 vs. 3.98 cm, p = 0.018). The particular calyx to be accessed should have a smaller length (2.22 vs. 3.19 cm, p = 0.012), larger angles (117.6 vs. 67.96, p<0.001) and larger infundibula (0.86 vs. 0.61 cm, p = 0.002). In the multivariate analysis, the only independent predictive factor for accessing a particular calyx was the angle between the entrance calyx and the calyx to be reached (OR 1.15, 95% confidence interval [CI], 1.053-1.256, p = 0.002). CONCLUSION: The angle between calyces obtained by multiplanar CT reconstruction is the only predictor of calyx access. .

Minimal fat renal angiomyolipoma with central scar and stellate calcification mimicking a calyceal calculus

Renal angiomyolipomas are benign neoplasms composed of varying amounts of adipose tissue, smooth muscles and blood vessels. They typically contain macroscopic fat, which is seen as negative attenuation on computed tomography. Calcification and scarring is rarely seen in renal angiomyolipomas. We report the case of a 40-year-old man who was found to have a renal angiomyolipoma with a central stellate scar and focal calcification. The lesion was initially misdiagnosed as a calyceal calculus.