Application of warning biopsies in percutaneous nephrolithotomy
Highlight box
Key findings
• If patients with kidney stones have the following factors, they should be suspected and undergo examination for renal pelvic tumors: advanced age, long history of kidney stones, severe hydronephrosis, urinary tract infection and kidney stone types.
What is known and what is new?
• The clinical characteristics of patients with malignant renal pelvis biopsy results are unknown.
• It is known that patients with renal calculi may be associated with renal pelvic tumors.
What is the implication, and what should change now?
• Renal pelvis mucosa should be carefully examined in patients with renal calculi undergoing percutaneous nephrolithotomy (PCNL). Renal pelvis mucosa biopsy is recommended if there is any abnormality or if the above five risk factors are combined.
• More data of patients undergoing PCNL for renal calculi with intraoperative renal pelvic mucosal biopsy are needed to obtain more convincing statistical data.
Introduction
Urolithiasis is a common disease of the urinary system, and many studies have shown a close relationship between calculi and tumors (1-3). Meta-analyses by Cheungpasitporn et al. (1) and a cohort study by van de Pol et al. (2) concluded that patients with kidney stones had a significantly increased risk of renal cell carcinoma (RCC) and upper urinary tract transitional cell carcinoma compared with patients without a history of kidney stones. A cohort study by Lin et al. (3) showed that patients diagnosed with stones had a 1.82-fold higher risk of developing urothelial cancer. The risk of kidney tumor is greatly increased in patients with kidney stones. Therefore, malignant kidney tumors should be suspected in patients with kidney stones, and a biopsy of possible abnormal mucosa should be taken, in combination with assessing the preoperative clinical characteristics and percutaneous nephrolithotomy (PCNL) findings. Therefore, the presurgical clinical characteristics of patients constituted our early warning information, and an early warning system was established using the presurgical data in combination with intraoperative abnormal mucous membrane observations. Suspicious mucous membranes observed microscopically were biopsied, i.e., an early warning biopsy. Establishment of an early warning system is to further study the relationship between renal calculi and renal pelvic tumors. We present this article in accordance with the STROBE reporting checklist (available at https://tau.amegroups.com/article/view/10.21037/tau-24-91/rc).
Methods
General information
Clinical data of 2,801 patients with renal calculi who underwent PCNL in the Department of Urology, Peking University People’s Hospital from January 2011 to November 2021 were retrospectively collected. The date of the pathological biopsy was the start time of follow-up, and the follow-up end point was December 1, 2022. This study was conducted in accordance with the Declaration of Helsinki (as revised in 2013) and was approved by the Ethics Committee of Peking University People’s Hospital (No. 2024PHB170-001). Informed consent was obtained from all participating patients.
The following were considered normal ranges of laboratory test results: urine white blood cell (WBC) count, 0–9/µL; urine red blood cell (RBC) count, 0–12/µL; serum creatinine level: male 59–104 µmol/L, female 45–84 µmol/L; and urine bacterial count: male 0–42/µL, female 0–930/µL.
Statistical analysis
The statistical software SPSS (version 26.0) was used for statistical analysis. Quantitative data are expressed as medians and interquartile ranges, and qualitative data are expressed as frequencies and percentages.
Operative method
All patients were placed in the prone position, with routine disinfection and draping. Under ultrasound guidance, the renal calyces were punctured in the posterior axillary line under the subcostal region. After urine was observed, the guidewire was inserted, the cannula was dilated, and a nephroscope and ultrasound probe were inserted. The stones were removed by pneumatic ballistic and holmium laser lithotripsy. After lithotripsy, the renal pelvic mucosa was observed under nephroscopy if the following abnormalities were found: mucosal hydropathy lesions, pedicled papillary masses, villous or polypoid masses, local mucosal lichenoid changes, or abnormal mucosal color of the kidney stone site. Mucosal biopsy forceps were used to extract a sample from the target area. Finally, a guidewire was inserted, the ureteral catheter was removed, ureteral stent was inserted under direct vision, and a nephrostomy tube was placed.
Results
A total of 69 patients underwent intraoperative mucosal biopsy, including 40 males and 29 females. The median follow-up time was 3.80 (0.27, 7.82) years. Among them, 34 (49.30%) had bilateral renal calculi, 11 (15.90%) had right renal calculi, 24 (34.80%) had left renal calculi, 38 (55.10%) underwent a left renal mucosal biopsy, and 30 (43.50%) underwent a right renal mucosal biopsy; one case underwent a bilateral renal biopsy. In total, 67 cases of preoperative hydronephrosis (95.71%) were observed. Biopsy results indicated that 8 cases were malignant (11.60%), and 61 cases were benign (88.40%). All malignant cases were renal pelvic carcinoma. Seven were urothelial carcinoma (the intraoperative nephroscopic findings in one of these cases are shown in Figure 1, 8 times magnification), and one of these was urothelial carcinoma with squamous differentiation. Only one was squamous. There is only one was squamous cell carcinoma. The general patient data are shown in Table 1.
Table 1
| Clinical characteristics | Male (n=40) | Female (n=29) |
|---|---|---|
| Urine white blood cell (/μL) | 97.50 (26.00, 912.50) | 552.00 (85.50, 1,585.50) |
| Urine red blood cell (/μL) | 61.50 (11.25, 397.50) | 30.00 (15.00, 80.00) |
| Urine bacterial count (/μL) | 24.00 (8.00, 622.00) | 586.00 (46.00, 3,254.00) |
| Urine pH | 6.00 (5.63, 6.88) | 6.25 (6.00, 6.50) |
| Urine nitrite (number of patients) | ||
| Positive | 6 (15.00) | 8 (27.60) |
| Serum creatinine (μmol/L) | 85.00 (73.00, 102.25) | 84.00 (59.50, 179.00) |
| Urine culture (number of patients) | ||
| Positive | 8 (20.00) | 16 (55.17) |
| Stone diameter (cm) | 2.30 (2.00, 3.625) | 3.00 (2.00, 4.05) |
| Degree of hydronephrosis | ||
| Mild | 9 (22.50) | 7 (24.10) |
| Moderate | 11 (27.50) | 7 (24.10) |
| Severe | 13 (32.50) | 11 (37.90) |
| History of kidney stones (months) | 30.00 (2.00, 120.00) | 67.00 (6.75, 177.00) |
Data are presented as M (P25, P75) or n (%). Hydronephrosis grading (according to the results of CT images): (I) no hydronephrosis: anteroposterior diameter of renal pelvis ≤10 mm, no dilatation of renal calices; (II) mild hydronephrosis: anteroposterior diameter of renal pelvis >10 mm, ≤20 mm, no dilatation of renal calices; (III) moderate hydronephrosis: anteroposterior diameter of renal pelvis >20 mm, ≤30 mm, accompanied by calyceal dilatation; (IV) severe hydronephrosis: anteroposterior diameter of renal pelvis >30 mm, accompanied by thinning of renal cortex. CT, computed tomography.
Detailed clinical data of eight cases of patients with malignant are shown in Table 2.
Table 2
| Sex | Age (y) | History of stones (y) | Degree of hydronephrosis | Ipsilateral surgery | Urinary infection | Stone type | Biopsy pathology | Treatment | Follow-up |
|---|---|---|---|---|---|---|---|---|---|
| Male | 65 | 1 | Mild + renal cyst | Yes | No | Multiple | Papillary high-grade UTUC | Endoscopic resection | 12 m, until FTD |
| Female | 40 | 10 | Severe | Yes | Yes | Staghorn | High-grade UTUC | Neoadjuvant chemotherapy (GC) and RNU | 7 m, then lost to follow-up |
| Male | 67 | 20 | NA | No | No | Staghorn | High-grade UTUC with squamous differentiation | Endoscopic ablation and neoadjuvant chemotherapy (GC) | 2 m, until FTD |
| Male | 56 | 3 | Severe | Yes | Yes | Multiple | Squamous cell carcinoma | Renal artery embolization | NA |
| Male | 50 | 3 | Severe | Yes | Yes | Multiple | Low-grade UTUC | RNU and adjuvant chemotherapy (GC) | 3.79 y (died of lung metastasis) |
| Female | 68 | 20 | Moderate | Yes | Yes | Staghorn | Low-grade UTUC with high grade component | Endoscopic resection | 10.90 y until FTD |
| Male | 58 | 0.25 | Severe | No | No | Multiple | Low-grade UTUC with high grade component | RNU | 10.84 y until FTD |
| Male | 79 | 0.25 | Severe + renal cyst | Yes | Yes | Multiple | UTUC | Renal artery embolization | 2 m, then died of other causes |
Hydronephrosis grading (according to the results of CT images): (I) no hydronephrosis: anteroposterior diameter of renal pelvis ≤10 mm, no dilatation of renal calices; (II) mild hydronephrosis: anteroposterior diameter of renal pelvis >10 mm, ≤20 mm, no dilatation of renal calices; (III) moderate hydronephrosis: anteroposterior diameter of renal pelvis >20 mm, ≤30 mm, accompanied by calyceal dilatation; (IV) severe hydronephrosis: anteroposterior diameter of renal pelvis >30 mm, accompanied by thinning of renal cortex. y, years; m, months; UTUC, upper tract urothelial carcinoma; FTD, follow-up termination date; GC, gemcitabine + cisplatin; RNU, radical nephroureterectomy; NA, not available; CT, computed tomography.
Discussion
At present, few articles on PCNL for renal calculi and renal pelvic tumors detected by intraoperative biopsy exist, which has provided limited guidance for clinical practice. This is the largest report of PCNL biopsy results for renal calculi and the most complete case report of calculi complicated by tumors from a single center. Yeh et al. studied the pathological results of non-functioning kidneys caused by kidney stones after nephrectomy and found that up to 51.06% of patients were diagnosed with malignant tumors after surgery. Among these patients, only 29.00% were suggested to have malignant renal tumors on preoperative imaging (4). In this study, only one of eight cases of renal pelvic carcinoma indicated tumors on preoperative imaging, and the remaining seven cases were diagnosed on intraoperative mucosal biopsy. Preoperatively diagnosing visible kidney tumors in patients with kidney stones is relatively difficult, for the following reasons. First, the symptoms of a renal pelvic tumor are masked by the severe pain of urinary calculi. Second, preoperative hydronephrosis, chronic inflammation, and infection makes finding tumors in the renal pelvis on preoperative imaging, including enhanced computed tomography (CT), difficult (5,6). Third, patients with renal insufficiency cannot undergo enhanced CT examination or venography (5). Fourth, due to kidney stone obstructions, tumor cells cannot be discharged through the urinary tract, resulting in a low urine cytology positivity rate (5,6). This group of eight patients had a preoperative urinary tract CT, plain film of kidney-ureter-bladder (KUB), and B-scan ultrasonography to wait in line, but only one patient was suspected of having a renal pelvic tumor, and the rest were not suspected of having a combination of kidney stones and tumors (preoperative CT images of some cases are shown in Figure 2). Therefore, making a definite preoperative diagnosis in patients with renal calculi and pelvic tumors is often difficult, and early warning biopsies should be performed. The patient’s preoperative clinical characteristics, such as the history of kidney stones, hydronephrosis, and urinary tract infections, were combined with intraoperative findings to establish an early warning system, and suspicious results underwent mucosal biopsy to allow early detection and treatment to improve the patient prognosis.
The relationship between kidney stones and renal pelvic tumors is unclear. The possible reasons include the following. First, kidney stones with long-term mechanical stimulation of mucous membranes cause local chronic inflammation and infection, resulting in urinary epithelial cell proliferation changes, including regeneration, metaplasia, and hyperplasia. Second, local inflammatory cells secrete cytokines, chemokines and free radicals produced by oxidative stimulation to promote tumor growth (6). Third, kidney stones that cause an obstruction allow carcinogens to function for a long time in the epithelium of the urinary tract, accelerating the tumor progression (5). According to previous studies (5,6), renal calculi combined with hydronephrosis and urinary tract infections have been suggested as risk factors for the occurrence of renal pelvic tumors, and such patients should be aware of the possibility of kidney stones combined with kidney tumors. In addition, if patients with kidney stones have the following factors, they should be suspected and undergo examination for renal pelvic tumors:
- Advanced age: the average age of the eight patients with malignant tumors in this group was 60.40 years, and seven patients were older than 50 years, as shown in Table 2;
- Long history of kidney stones: 6 cases (75.00%) had a history of kidney stones of more than 1 year, as shown in Table 2, and almost all patients with combined pelvic malignant tumors had a history of kidney stones of >1 year. A small kidney stone burden may cause no symptoms, and the kidney stone history may actually be longer;
- Severe hydronephrosis: this study had 5 cases (62.50%) of severe preoperative hydronephrosis. In a case report by He et al. (5), 5 patients had severe hydronephrosis;
- Urinary tract infection: in this study, 5 cases (62.50%) were complicated with urinary tract infections. Of the 21 patients in Table 3, 10 patients did not mention whether or not they had a urinary tract infection; of the other 11 patients, 9 (81.82%) had urinary tract infections;
- Kidney stone types: the eight patients in this study had multiple stones. In the cases reported in Table 3, eight patients had multiple stones and nine patients had staghorn stones. In a report by An et al., four of six patients had multiple or staghorn stones (6). Considering that multiple stones and staghorn calculi have larger renal pelvic mucous membrane contact areas, the stronger stimulation of the renal pelvic mucous membranes causes more serious outflow obstructions.
Table 3
| Authors | Number of cases | Sex | Age (y) | History of stones | UTI | Stone type | Treatment | Pathology | Follow-up |
|---|---|---|---|---|---|---|---|---|---|
| Nakano et al. (7) | 1 | Male | 70 | NA | NA | Stones in calyceal diverticula | RNU | SCC + UC | 5 y, no progression |
| Xiao et al. (8) | 2 | Female | 55 | 10 y | Yes | Single | Radical nephrectomy | SCC | 12 m, died of metastatic liver tumor |
| Male | 61 | 5 y | Yes | Single | Radical nephrectomy | SCC | NA, died of severe pulmonary infection complication | ||
| Kumar et al. (9) | 1 | Male | 75 | 30 y | No | Multiple | Radical nephrectomy | SCC | 3 m, no progression |
| Wu et al. (10) | 2 | Male | 77 | 2 y | NA | Staghorn | PCNL → nephrectomy | SCC | 1 m, died of metastatic disease |
| Female | 54 | 5 y | NA | Staghorn | PCNL → palliative treatment | SCC | 3 m, died of severe complications | ||
| Kivlin et al. (11) | 1 | Male | 77 | Many years | Yes | Staghorn | Nephrectomy | SCC | NA |
| Kondisetty et al. (12) | 1 | Female | 60 | NA | Yes | Staghorn | Nephrectomy → chemotherapy | SCC | 16 m, died of tumor progression |
| Hosseinzadeh et al. (13) | 1 | Female | 59 | 14 m | No | Staghorn | Radical nephrectomy | SCC | 1 y, died of tumor progression |
| Kasahara et al. (14) | 1 | Female | 70 | NA | Yes | Staghorn | Nephrectomy | SCC | 2 m, died of tumor progression |
| Tsuboi et al. (15) | 1 | Male | 66 | 20 y | Yes | Staghorn | ECIRS → chemotherapy and pembrolizumab | UC | 7 m, died of tumor progression |
| Chang et al. (16) | 1 | Female | 69 | Many years | Yes | Staghorn | Radical nephrectomy | SCC | 4 m, no progression |
| Aggarwal et al. (17) | 1 | Male | 54 | 10 m | Yes | Multiple | RNU | UC | 1 y, died of tumor progression |
| Yu et al. (18) | 1 | Female | 64 | 1 y | NA | Multiple | laparoscopic nephrectomy | RCC | 3 m, died of tumor progression |
| Liu et al. (19) | 1 | Female | 54 | 6 m | NA | Multiple | Radical nephrectomy and chemotherapy | SCC with dedifferentiated sarcomatosis | 7 m, died of tumor metastases |
| Huang et al. (20) | 1 | Male | 82 | NA | NA | Multiple | Radical nephrectomy | SCC | 10 m, died of tumor metastases |
| Satwikananda et al. (21) | 1 | Male | 56 | 3 m | NA | Staghorn | RNU | RCC | NA |
| He et al. (5) | 5 | Male | 80 | 3 w | Yes | Multiple | Renal artery embolization | RCC | NA |
| Male | 60 | 2 m | NA | Multiple | Renal artery embolization | RCC | 42 m, until FTD | ||
| Male | 58 | 20 y | NA | NA | Give up treatment | NA | FTD | ||
| Male | 53 | 3 m | NA | NA | RNU | RCC | 33 m, until FTD | ||
| Female | 70 | 5 y | NA | Multiple | Conservation treatment | RCC | 11 m, until FTD |
y, years; UTI, urinary tract infection; NA, not available; RNU, radical nephroureterectomy; SCC, squamous cell carcinoma; UC, urothelial carcinoma; PCNL, percutaneous nephrolithotomy; FTD, follow-up termination date; w, weeks; m, months; ECIRS, endoscopic combined intrarenal surge; RCC, renal cell carcinoma.
Because diagnosing renal calculi complicated by renal tumors before surgery is difficult, it is necessary to carefully and comprehensively explore the mucosa of various parts of the renal pelvis during PCNL in patients with renal calculi and the above risk factors. Mucosal biopsy during PCNL is an effective and accurate auxiliary diagnostic method; however, no unified indication for mucosal biopsy currently exists. Based on previous case reports and the eight patients in this study, we summarized the mucosal abnormalities by biopsy, including mucosal hydropathy lesions, pedicled papillary masses, villous or polypoid masses, local mucosal lichenoid changes, and abnormal mucosal color at the kidney stone site. If the above mucosal changes are detected intraoperatively, the possibility of a tumor should be highly suspected, and a warning biopsy should be performed.
Once the mucosal biopsy indicates malignancy, renal pelvic carcinoma should be treated and diagnosed according to the guidelines. Simultaneously, comprehensive consideration should be given to various aspects, including the tumor risk stratification, physical condition, and renal function, and individualized treatment should be selected. In this study, eight patients had carcinoma of the renal pelvis; two underwent radical surgery, three underwent local electrocautery or laser ablation of the tumor, two underwent palliative renal artery embolization, and one underwent radical surgery for a renal artery embolism. Notably, one patient with low-grade urothelial carcinoma with focal high-grade components underwent renal-sparing surgery and survived for more than 10 years. Two patients with high-grade carcinomas underwent local electrocautery or laser ablation, and no recurrence was observed within one year of surgery. Li et al. (22) suggested that UC usually cannot be cured, and the 5-year survival rate is approximately 15%. Except for one case in our postoperative group that was lost to follow-up, the other seven patients survived, indicating that promptly using the PCNL technique for the early detection of abnormal mucosal biopsies from malignant tumors of the renal pelvis and selecting the appropriate operative method can achieve good prognoses. Because of the small sample size of this study, each treatment regimen’s effectiveness is not truly represented, and results are only useful for clinical reference. This study had some limitations. First, this was a retrospective study, which was subject to selection bias. Second, the sample size of this study was limited, and some patients were lost to early follow-up; therefore, accurately determining the malignant transformation in various pathological conditions was impossible.
Conclusions
In conclusion, patient indicators should be comprehensively evaluated before PCNL. For patients aged >50 years with a history of kidney stones of >1 year, severe hydronephrosis, urinary tract infections, and multiple large stones, the intraoperative mucosal condition should be comprehensively and carefully observed. Once a mucosal abnormality is detected, an early warning biopsy should be performed. A warning-type biopsy can help identify patients with malignant tumors and provide timely treatment to improve their prognosis.
Acknowledgments
Funding: This study was supported by
Footnote
Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://tau.amegroups.com/article/view/10.21037/tau-24-91/rc
Data Sharing Statement: Available at https://tau.amegroups.com/article/view/10.21037/tau-24-91/dss
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Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tau.amegroups.com/article/view/10.21037/tau-24-91/coif). The authors have no conflicts of interest to declare.
Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study was approved by the Ethics Committee of Peking University People’s Hospital (No. 2024PHB170-001). Informed consent was obtained from all participating patients.
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References
- Cheungpasitporn W, Thongprayoon C, O’Corragain OA, et al. The risk of kidney cancer in patients with kidney stones: a systematic review and meta-analysis. QJM 2015;108:205-12. [Crossref] [PubMed]
- van de Pol JAA, van den Brandt PA, Schouten LJ. Kidney stones and the risk of renal cell carcinoma and upper tract urothelial carcinoma: the Netherlands Cohort Study. Br J Cancer 2019;120:368-74. [Crossref] [PubMed]
- Lin CL, Huang WT, Fan WC, et al. Associations between interventions for urolithiasis and urinary tract cancer among patients in Taiwan: The effect of early intervention. Medicine (Baltimore) 2016;95:e5594. [Crossref] [PubMed]
- Yeh CC, Lin TH, Wu HC, et al. A high association of upper urinary tract transitional cell carcinoma with nonfunctioning kidney caused by stone disease in Taiwan. Urol Int 2007;79:19-23. [Crossref] [PubMed]
- He CJ, Qin CP, Li JX, et al. Diagnosis and treatment of hydrocephalus-accompanied renal calculi complicated with renal tumor: 5 case reports. Beijing Da Xue Xue Bao Yi Xue Ban 2014;46:558-62. [PubMed]
- An L, Xiong L, Xu Q, et al. Incidental Diagnosis of Renal Pelvic Tumor in Patients Who Underwent Percutaneous Nephrolithotomy: A Report of 6 Cases and Review of the Literature. Urology 2023;171:64-70. [Crossref] [PubMed]
- Nakano T, Kitagawa Y, Izumi K, et al. Invasive urothelial carcinoma within a calyceal diverticulum associated with renal stones: A case report. Oncol Lett 2015;10:2439-41. [Crossref] [PubMed]
- Xiao J, Lei J, He L, et al. Renal calculus complicated with squamous cell carcinoma of renal pelvis: Report of two cases. Can Urol Assoc J 2015;9:E310-2. [Crossref] [PubMed]
- Kumar S, Tomar V, Yadav SS, et al. Primary Squamous Cell Carcinoma of Kidney Associated With Large Calculus in Non-functioning Kidney: A Case Report. Urol Case Rep 2016;8:4-6. [Crossref] [PubMed]
- Wu CQ, Matulay JT, Gupta M, et al. Unsuspected Malignancy During Percutaneous Nephrolithotomy: The Snake in the Grass. J Endourol Case Rep 2016;2:184-8. [Crossref] [PubMed]
- Kivlin D, Tong C, Friedlander J, et al. Sarcomatoid Squamous Cell Carcinoma of the Renal Pelvis Masquerading as Emphysematous Pyelonephritis with Staghorn Calculus. J Endourol Case Rep 2016;2:87-9. [Crossref] [PubMed]
- Kondisetty S, Borkar PV, Thomas A. Nephrectomy for infected stag horn calculus confounded by the presence of squamous cell carcinoma. BMJ Case Rep 2017;2017:bcr2017220230. [Crossref] [PubMed]
- Hosseinzadeh M, Mohammadzadeh S. Primary Pure Squamous Cell Carcinoma of Kidney Associated with Multiple Stag Horn Stones. Int Med Case Rep J 2020;13:261-3. [Crossref] [PubMed]
- Kasahara R, Kawahara T, Tajiri R, et al. Renal Squamous Cell Carcinoma with Staghorn Calculus. Case Rep Oncol 2020;13:403-7. [Crossref] [PubMed]
- Tsuboi I, Maruyama Y, Araki M, et al. Advanced Renal Pelvic Carcinoma Revealed after Treatment of a Staghorn Calculus by Endoscopic Combined Intrarenal Surgery. Case Rep Urol 2020;2020:9703479. [Crossref] [PubMed]
- Chang TH, Tseng JS. Rare squamous cell carcinoma of the kidney with concurrent xanthogranulomatous pyelonephritis: A case report and review of the literature. Open Med (Wars) 2021;16:128-33. [Crossref] [PubMed]
- Aggarwal D, Parmar K, Yadav AK, et al. Large distal ureteric stone with high burden urothelial cancer of the entire ureter and renal pelvis: a dual pathology. Ann R Coll Surg Engl 2021;103:e136-9. [Crossref] [PubMed]
- Yu Q, Wu Y, Yao L, et al. Upper ureteral calculi complicating severe hydronephrosis and renal medullary carcinoma in an elderly Chinese woman. Asian J Surg 2023;46:2166-7. [Crossref] [PubMed]
- Liu XH, Zou QM, Cao JD, et al. Primary squamous cell carcinoma with sarcomatoid differentiation of the kidney associated with ureteral stone obstruction: A case report. World J Clin Cases 2022;10:11942-8. [Crossref] [PubMed]
- Huang H, Li L, Cao Q, et al. Renal squamous cell carcinoma with extensive stones. Am J Med Sci 2023;365:e69-70. [Crossref] [PubMed]
- Satwikananda H, Wiratama MA, Putri KTC, et al. Renal cell carcinoma in a patient with staghorn stones: A case report. Int J Surg Case Rep 2023;110:108678. [Crossref] [PubMed]
- Li YY, Li XL, Dong ZL. A case report of renal pelvis carcinoma. Am J Transl Res 2023;15:310-5. [PubMed]
