Triple Pathology in a Horseshoe Kidney: A Rare Case of Concurrent Urothelial Carcinoma, Urolithiasis, and Renal Atrophy with Analysis of Multimodal Management

Triple Pathology in a Horseshoe Kidney: A Rare Case of Concurrent Urothelial Carcinoma, Urolithiasis, and Renal Atrophy with Analysis of Multimodal Management | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Case Report Triple Pathology in a Horseshoe Kidney: A Rare Case of Concurrent Urothelial Carcinoma, Urolithiasis, and Renal Atrophy with Analysis of Multimodal Management Longyuhe Yang, Yueqiang Wang, Yu Tian, Zhen Ma, Yunliang Zhao, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6774249/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 12 You are reading this latest preprint version Abstract Horseshoe kidney (HSK) is a rare congenital anomaly with an incidence of approximately 0.25% in the general population. The unique anatomical structure of HSK often leads to vascular and excretory abnormalities, complicating the diagnosis and management of coexisting diseases. We present a rare case of a 46-year-old male with HSK who was simultaneously diagnosed with urothelial carcinoma, urolithiasis, and renal atrophy. Given contralateral renal atrophy, radical nephrectomy was contraindicated to avoid lifelong dialysis. Instead, a percutaneous approach was employed to excise the renal mass and remove the kidney stones in a single session. Postoperative pathology confirmed high-grade urothelial carcinoma with squamous differentiation. Adjuvant chemotherapy with the Gemcitabine-Cisplatin (GC) regimen was initiated, and the patient showed no significant adverse effects after one cycle. This case highlights the challenges in managing complex pathologies in HSK and underscores the importance of minimally invasive techniques and multidisciplinary approaches in advanced cases. Horseshoe kidney urothelial carcinoma urolithiasis renal atrophy minimally invasive surgery chemotherapy Figures Figure 1 Figure 2 Introduction Horseshoe kidney (HSK) is a congenital renal anomaly characterized by the fusion of the two kidneys, typically at their lower poles, forming a U-shaped structure resembling a horseshoe. This malformation is relatively rare in the general population, with an estimated prevalence of approximately 0.25%. It is often associated with an increased risk of developing other urological conditions, such as urinary tract calculi and urothelial carcinoma [ 1 ]. Upper tract urothelial carcinoma (UTUC) is an uncommon malignancy. Its complex nature lies in its reduced accessibility, which poses challenges for accurate local staging during endoscopic biopsy and endoscopic management. Consequently, radical surgery remains the standard treatment for high-risk or poorly differentiated cases [ 2 ]. Although the clinical manifestations of horseshoe kidney have been extensively reported, cases involving the triple coexistence of horseshoe kidney, urinary calculi, and urothelial carcinoma are relatively scarce. This article reports a rare case of horseshoe kidney in which the patient presented with concurrent urinary calculi and urothelial carcinoma in the right kidney. We will discuss its clinical characteristics, diagnostic process, and treatment strategy. Case Report/Case Presentation This case involves a 46-year-old male patient with a previously good health status. The patient presented two months ago with recurrent right-sided abdominal pain and gross hematuria, accompanied by dysuria and intermittent fever. An ultrasound performed at an external hospital revealed right-sided renal calculi with hydronephrosis, left renal atrophy, and a fused horseshoe kidney. Consequently, the patient was referred to our hospital for further evaluation and management. Upon admission, laboratory findings included a serum creatinine level of 176.5 µmol/L, eGFR ≈ 35 mL/min/1.73m², CKD stage 3b. Urinalysis indicated a urinary tract infection, and urine culture identified Staphylococcus aureus as the causative pathogen. Preoperative urine cytology examinations were performed consecutively three times, with no evidence of malignant cells detected. A subsequent CT scan demonstrated multiple enlarged and necrotic lymph nodes in the retroperitoneum. Further evaluation with contrast-enhanced CT revealed an irregular space-occupying lesion within the right kidney, suggestive of renal pelvic carcinoma (Fig. 1 ).The patient was started on sensitive antibiotic therapy to address the infection. Definitive treatment planning will be determined following adequate control of the infection. While radical nephroureterectomy remains the standard treatment for UTUC, this patient presents unique challenges. The presence of left renal atrophy means that radical resection of the right kidney (the affected side) carries a significant risk of requiring lifelong dialysis. Furthermore, preoperative imaging revealed suspicious lymph node involvement, suggestive of advanced UTUC. In accordance with the 2023 EAU (European Association of Urology) Guidelines regarding renal function preservation strategies for advanced UTUC, the risks and benefits were thoroughly discussed with the patient and family. Ureteroscopic biopsy was deemed high-risk due to severe hydronephrosis and pyonephrosis; thus, a percutaneous approach was preferred for combined tumor resection and stone clearance.Following this informed consent process, the decision was made to proceed with "percutaneous resection of the renal mass via electrocautery combined with percutaneous nephrolithotomy (PCNL)". The goals of this procedure are threefold: 1) to obtain definitive histopathological diagnosis of the tumor nature, 2) to prepare for subsequent adjuvant therapy, and 3) to simultaneously clear the right renal calculi. Following the induction of effective anesthesia, the patient was placed in the lithotomy position. The surgical field was prepared and draped sterilely. An F8/9.8 ureteroscope was inserted into the bladder.No obvious abnormalities were observed within the bladder lumen. The patient was then repositioned into the prone position. The surgical field was re-prepped and draped sterilely. Under ultrasound guidance, the right renal collecting system was accessed via puncture through the right 11th intercostal space.Urine return was confirmed, and a guidewire was inserted. A small scalpel was used to make a 0.5 cm skin incision. The tract was dilated over the guidewire using an F24 dilator, and an F24 working sheath was placed. The ureteroscope was introduced through the sheath into the renal collecting system.Multiple papillary masses and calculi were visualized within the renal pelvis. The urine appeared turbid with abundant flocculent debris. Stones were found impacted at the calyceal necks.Holmium laser lithotripsy was employed to fragment the impacted stones, which were then flushed out via hydrostatic pressure irrigation.Copious purulent discharge was noted during the procedure.The ureteral catheter was removed. An F5 double-J ureteral stent was inserted antegradely over the guidewire.A GYRUS PK (Plasmakinetic) bipolar resectoscope was then introduced through the F24 working sheath into the renal pelvis. Using the PK cutting loop, the raised tumor masses were partially resected, and the specimens were sent for pathological examination. The resection bed was thoroughly cauterized for hemostasis using the resectoscope electrode.Upon inspection confirming no active bleeding points, the resectoscope was withdrawn. An Foley catheter was inserted through the nephrostomy tract to serve as a right nephrostomy tube. The balloon was inflated with 3 ml of sterile water. Anesthesia was maintained effectively throughout the procedure. The surgery proceeded smoothly without significant hemorrhage. The patient was transported to the recovery room in stable condition upon completion of the operation. For patients with muscle-invasive urothelial carcinoma, the standard systemic chemotherapy regimens are typically"MVAC" (Methotrexate, Vinblastine, Doxorubicin, Cisplatin)or"GC" (Gemcitabine, Cisplatin).Although the MVAC regimen can be highly effective, it is associated with a higher toxicity profile. Given the patient's relatively poor general condition, the GC regimen was selected as the preferred treatment option. The patient has now completed one cycle of GC chemotherapy. Follow-up imaging with chest CT and contrast-enhanced abdominal CT showed no evidence of disease progression in terms of the maximum tumor diameter or the areas of necrotic retroperitoneal lymph nodes. Tumor marker levels also showed no significant elevation. The patient's serum creatinine levels have remained stable within the range of 126.5–139.6 µmol/L. Discussion HSK is a rare congenital renal fusion anomaly. Epidemiological studies indicate a prevalence of approximately 0.25% in the general population [ 1 ], with a male-to-female ratio of about 2:1 [ 2 ]. Its formation is likely the result of the fusion of the two umbilical arteries during early embryonic development [ 3 , 4 ].The anatomical anomalies associated with HSK encompass several aspects:Vascular Variations:Aberrant vasculature, including blood supply variations. These variant vessels may originate from the inferior mesenteric artery, abdominal aorta, contralateral renal artery, common iliac artery, and internal iliac artery [ 5 ].Ureteral Course:The two renal moieties are connected by an isthmus, which causes the ureters to pass ventrally over it, potentially leading to compression.Renal Rotation:Malrotation results in the renal hila facing anteriorly (ventrally).This abnormal anatomical position frequently leads to impaired urinary drainage, constituting a significant cause of chronic urinary tract obstruction. This obstruction is also a contributing factor to the high incidence of nephrolithiasis in HSK patients. UTUC accounts for a small proportion (5%-10%) of all urothelial carcinomas. While no established direct association between HSK and UTUC is known, some reports suggest that the incidence of renal pelvic carcinoma in HSK patients is at least three times higher than in the general population. This increased occurrence is often attributed to chronic noxious stimuli related to infection, urinary stasis, and calculi; however, the precise pathological mechanisms remain unclear. Japanese researchers reviewed 24 previously reported cases of renal pelvic tumors in HSK. Seven of these cases (30%) contained a squamous cell carcinoma component[ 6 ]. The renal pelvic tumor in our patient also presented as an invasive high-grade urothelial carcinoma with squamous differentiation, suggesting that squamous differentiation may be associated with chronic inflammation inherent to the HSK environment. The squamous differentiation observed in our case aligns with the hypothesis that chronic inflammation secondary to urinary stasis and calculi in HSK may drive metaplastic changes. Distinguishing whether an invasive renal mass is of urothelial or renal cortical origin can be difficult. This distinction is critical for treatment planning. Renal cortical tumors typically necessitate radical nephrectomy or partial nephrectomy. Conversely, urothelial carcinoma originating from the renal pelvis mandates radical nephroureterectomy(removal of the entire upper urinary tract, including kidney, ureter, and bladder cuff). A study by Yasuda et al. [ 7 ] examining pathology in 49 HSK patients with renal masses found only 27 (55%) were renal cell carcinoma (RCC), while 22 (45%) were benign. This highlights that partial nephrectomy offers significant functional advantages for HSK patients with renal masses. The incidence of RCC appears lower than expected in HSK, with benign and non-invasive tumors being relatively common. Multiphasic CT is an excellent tool for differentiating tumor types.However, biopsy or positive urine cytology is still recommended to confirm the diagnosis. While ureteroscopic biopsy can be used for confirmation, it has been associated with an increased risk of intravesical recurrence[ 8 ]. We employed percutaneous tumor resection via electrocautery for this patient. This approach offered multiple benefits:Ensured adequate tissue sampling, minimizing the risk of false-negative pathological results.Provided a cytoreductive effect and achieved effective hemostasis.Simultaneously allowed removal of the renal calculi, thereby resolving the obstruction-induced urinary tract infection.Prepared the patient for subsequent adjuvant therapy.Treatment Rationale Based on Potential Pathology:Had the postoperative pathology indicated a RCC,partial nephrectomy could have been performed. This strategy would have avoided the need for long-term postoperative dialysis. This approach has been previously reported in cases of HSK associated with renal tumors [ 9 ]. Furthermore, Latif et al. [ 10 ]reported a case of robot-assisted radical surgery in an HSK patient with normal bilateral renal function who did not require postoperative dialysis. However, the postoperative pathology in this case confirmed urothelial carcinoma. Standard radical surgery for UTUC mandates right radical nephroureterectomy with excision of the bladder cuff.Given the patient's left renal atrophy, this radical surgery would have resulted in lifelong dialysis dependency. Additionally, the presence of suspected lymph node metastasis indicated advanced disease. After thoroughly discussing the disease status, prognosis, and treatment options with the patient, the decision was ultimately made to proceed with the GC chemotherapy regimen as adjuvant therapy. Declarations Statements Written informed consent was obtained from the patient for publication of this case report and any accompanying images. Acknowledgement (optional) Ethics approval and consent to participate Not applicable. Conflict of Interest Statement The authors have no conflicts of interest to declare. Funding Sources Grants from the research project at Qingdao University (YLJT20231002).The funders had no role in this study. Author Contributions LY,YZ,YT and YW analyzed and interpreted the patient data and drafted the paper. LY and YW contributed equally to this work.ZZ,XH,ZM,JY,QL conceptualized the study and design, analysis, and interpretation of data. All authors contributed to the article and approved the submitted version. Data Availability Statement All data generated or analyzed during this study are included in this article. Further inquiries can be directed to the corresponding author. Consent for publication Written informed consent for publication of their clinical details and clinical images was obtained from the patient parents. A copy of the consent form is available to the Editor of this journal. References Tkocz M, Kupajski M. Tumour in horseshoe kidney—different surgical treatment shown in five example cases. Contemp Oncol (Pozn). 2012;16(3):254-257. Soria F, Shariat SF, Lerner SP, et al. Epidemiology, diagnosis, preoperative evaluation and prognostic assessment of upper-tract urothelial carcinoma (UTUC). World Journal of Urology, 2017, 35(3): 379–387. Houat AP, Guimaraes CTS, Takahashi MS, Rodi GP, Gasparetto TPD, Blasbalg R, et al. Congenital anomalies of the upper urinary tract: A comprehensive review. Radiographics, 2021, 41: 462–486. doi: 10.1148/rg.2021200078. Schiappacasse G, Aguirre J, Soffia P, et al. CT findings of the main pathological conditions associated with horseshoe kidneys. British Journal of Radiology, 2015, 88: 20140456. doi: 10.1259/bjr.20140456. Majos M, Polguj M, Szemraj-Rogucka Z, et al. The level of origin of renal arteries in horseshoe kidney vs. in separated kidneys: CT-based study. Surgical and Radiologic Anatomy, 2018, 40: 1185–1191. doi: 10.1007/s00276-018-2071-8. Mizusawa H, Komiyama I, Ueno Y, et al. Squamous cell carcinoma in the renal pelvis of a horseshoe kidney. International Journal of Urology, 2004, 11(9): 782–784. Yasuda Y, Zhang JJ, Attawettayanon W, et al. Pathologic findings and management of renal mass in horseshoe kidneys. Urology, 2022, 166: 170–176. doi: 10.1016/j.urology.2022.03.020. Guo RQ, Hong P, Xiong GY, et al. Impact of ureteroscopy before radical nephroureterectomy for upper tract urothelial carcinomas on oncological outcomes: a meta-analysis. BJU International, 2017, 121(2): 184–193. doi: 10.1111/bju.14053. Quintana Álvarez R, Herranz Amo F, Bueno Chomón G, et al. Surgical management of horseshoe kidney tumors: Literature review and analysis of two cases. Actas Urológicas Españolas (English Edition), 2021, 45(7): 493–497. Latif ER, Ahmed I, Thomas M, Eddy B. Robotic nephroureterectomy in a horseshoe kidney for upper tract urothelial carcinoma. BMJ Case Reports, 2021, 14(6): e234901. doi: 10.1136/bcr-2020-234901. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 01 Aug, 2025 Reviewers agreed at journal 23 Jul, 2025 Reviews received at journal 19 Jul, 2025 Reviews received at journal 10 Jul, 2025 Reviewers agreed at journal 10 Jul, 2025 Reviewers agreed at journal 06 Jul, 2025 Reviewers agreed at journal 04 Jul, 2025 Reviewers invited by journal 03 Jul, 2025 Editor invited by journal 04 Jun, 2025 Editor assigned by journal 31 May, 2025 Submission checks completed at journal 31 May, 2025 First submitted to journal 29 May, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6774249","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":481321818,"identity":"ba62be31-af86-4d1f-81cb-f9784499f1cd","order_by":0,"name":"Longyuhe Yang","email":"","orcid":"","institution":"Southern Central Hospital of Yunnan Province (First People’s Hospital of Honghe State）","correspondingAuthor":false,"prefix":"","firstName":"Longyuhe","middleName":"","lastName":"Yang","suffix":""},{"id":481321819,"identity":"10fd854c-9576-44c8-843a-4aa31381ddcd","order_by":1,"name":"Yueqiang Wang","email":"","orcid":"","institution":"Southern Central Hospital of Yunnan Province (First People’s Hospital of Honghe State）","correspondingAuthor":false,"prefix":"","firstName":"Yueqiang","middleName":"","lastName":"Wang","suffix":""},{"id":481321820,"identity":"4c1bc2b2-a537-4828-b44a-1df0d11d7beb","order_by":2,"name":"Yu Tian","email":"","orcid":"","institution":"Southern Central Hospital of Yunnan Province (First People’s Hospital of Honghe State）","correspondingAuthor":false,"prefix":"","firstName":"Yu","middleName":"","lastName":"Tian","suffix":""},{"id":481321821,"identity":"97840554-8143-474e-86ab-434d78f4c754","order_by":3,"name":"Zhen Ma","email":"","orcid":"","institution":"Southern Central Hospital of Yunnan Province (First People’s Hospital of Honghe State）","correspondingAuthor":false,"prefix":"","firstName":"Zhen","middleName":"","lastName":"Ma","suffix":""},{"id":481321822,"identity":"a60f6826-9493-4665-aa0a-2c69f1e1474d","order_by":4,"name":"Yunliang Zhao","email":"","orcid":"","institution":"Southern Central Hospital of Yunnan Province (First People’s Hospital of Honghe State）","correspondingAuthor":false,"prefix":"","firstName":"Yunliang","middleName":"","lastName":"Zhao","suffix":""},{"id":481321824,"identity":"a02a7b72-ce9f-408f-9012-80e1c2024b1a","order_by":5,"name":"Jianbing Yang","email":"","orcid":"","institution":"Southern Central Hospital of Yunnan Province (First People’s Hospital of Honghe State）","correspondingAuthor":false,"prefix":"","firstName":"Jianbing","middleName":"","lastName":"Yang","suffix":""},{"id":481321825,"identity":"548c684d-39d7-4eb7-b1ce-dc17d5a0a38e","order_by":6,"name":"Na Wei","email":"","orcid":"","institution":"Southern Central Hospital of Yunnan Province (First People’s Hospital of Honghe State）","correspondingAuthor":false,"prefix":"","firstName":"Na","middleName":"","lastName":"Wei","suffix":""},{"id":481321826,"identity":"e2254e53-21ed-42f8-b1b2-1d0a9fd07d2e","order_by":7,"name":"Xuehua Wang","email":"","orcid":"","institution":"Southern Central Hospital of Yunnan Province (First People’s Hospital of Honghe State）","correspondingAuthor":false,"prefix":"","firstName":"Xuehua","middleName":"","lastName":"Wang","suffix":""},{"id":481321829,"identity":"69be674a-1295-456a-9147-8854da25f5c5","order_by":8,"name":"Zhigang Zhang","email":"","orcid":"","institution":"Southern Central Hospital of Yunnan Province (First People’s Hospital of Honghe State）","correspondingAuthor":false,"prefix":"","firstName":"Zhigang","middleName":"","lastName":"Zhang","suffix":""},{"id":481321831,"identity":"07541cb2-f5b3-47a0-8e10-a43a6a878606","order_by":9,"name":"Qiuyi Lu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAy0lEQVRIie3RvQrCMBDA8ZRApkAdzyX6CFcCdembuKQInSoUXDsUCjqJr1LwBSKBuohdHfsIcXMQ/BgdpHFzyG/On7sjhHjePwprHVl8iJDSQ++WQKtWUFA53rAFOo7Jp5ZbmjYdj0due1WnoAFkUhoSE1Im8+G9zNZggVzEhmQ9abNlNdjoc4aAIF/JEYPKDCcTnc9uHDHd18EanBLUOSJHlTaUMrckurRKAmoJhlFULreI7v2Vdy3CXXftbZk4nP9B/fbc8zzP++YJBEZAgEQLiiUAAAAASUVORK5CYII=","orcid":"","institution":"Southern Central Hospital of Yunnan Province (First People’s Hospital of Honghe State）","correspondingAuthor":true,"prefix":"","firstName":"Qiuyi","middleName":"","lastName":"Lu","suffix":""}],"badges":[],"createdAt":"2025-05-29 08:08:38","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6774249/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6774249/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":86216242,"identity":"df850798-7e6a-44f5-84e8-2c8abe0e4a68","added_by":"auto","created_at":"2025-07-08 06:05:14","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1285671,"visible":true,"origin":"","legend":"\u003cp\u003eA. Right renal calculi\u003cbr\u003e\nB. Fusion of the renal isthmus \u003cbr\u003e\nC. Atrophy of the left kidney\u003cbr\u003e\nD. Mass in the right kidney\u003cbr\u003e\nE. Enlarged necrotic retroperitoneal lymph nodes encircling the abdominal aorta\u003c/p\u003e","description":"","filename":"fig1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6774249/v1/6b683d8b55b5b0b3052df4b0.jpg"},{"id":86215730,"identity":"d4c073b1-4a22-471c-af4d-c5b78e189c0f","added_by":"auto","created_at":"2025-07-08 05:57:14","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":280822,"visible":true,"origin":"","legend":"\u003cp\u003ePathological section of the right renal mass showing high-grade urothelial carcinoma with squamous differentiation (H\u0026amp;E stain, ×200)\u003c/p\u003e","description":"","filename":"fig2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6774249/v1/730c00d6ed687ad7a9c886b1.jpg"},{"id":86216859,"identity":"68902fef-c2be-4e5c-ba09-43b89c7351b1","added_by":"auto","created_at":"2025-07-08 06:13:14","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2028021,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6774249/v1/7d23cf3d-0591-4826-a3ce-6fad9ad2515a.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Triple Pathology in a Horseshoe Kidney: A Rare Case of Concurrent Urothelial Carcinoma, Urolithiasis, and Renal Atrophy with Analysis of Multimodal Management","fulltext":[{"header":"Introduction","content":"\u003cp\u003eHorseshoe kidney (HSK) is a congenital renal anomaly characterized by the fusion of the two kidneys, typically at their lower poles, forming a U-shaped structure resembling a horseshoe. This malformation is relatively rare in the general population, with an estimated prevalence of approximately 0.25%. It is often associated with an increased risk of developing other urological conditions, such as urinary tract calculi and urothelial carcinoma [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eUpper tract urothelial carcinoma (UTUC) is an uncommon malignancy. Its complex nature lies in its reduced accessibility, which poses challenges for accurate local staging during endoscopic biopsy and endoscopic management. Consequently, radical surgery remains the standard treatment for high-risk or poorly differentiated cases [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAlthough the clinical manifestations of horseshoe kidney have been extensively reported, cases involving the triple coexistence of horseshoe kidney, urinary calculi, and urothelial carcinoma are relatively scarce. This article reports a rare case of horseshoe kidney in which the patient presented with concurrent urinary calculi and urothelial carcinoma in the right kidney. We will discuss its clinical characteristics, diagnostic process, and treatment strategy.\u003c/p\u003e"},{"header":"Case Report/Case Presentation","content":"\u003cp\u003eThis case involves a 46-year-old male patient with a previously good health status. The patient presented two months ago with recurrent right-sided abdominal pain and gross hematuria, accompanied by dysuria and intermittent fever. An ultrasound performed at an external hospital revealed right-sided renal calculi with hydronephrosis, left renal atrophy, and a fused horseshoe kidney. Consequently, the patient was referred to our hospital for further evaluation and management.\u003c/p\u003e \u003cp\u003eUpon admission, laboratory findings included a serum creatinine level of 176.5 \u0026micro;mol/L, eGFR\u0026thinsp;\u0026asymp;\u0026thinsp;35 mL/min/1.73m\u0026sup2;, CKD stage 3b. Urinalysis indicated a urinary tract infection, and urine culture identified Staphylococcus aureus as the causative pathogen. Preoperative urine cytology examinations were performed consecutively three times, with no evidence of malignant cells detected.\u003c/p\u003e \u003cp\u003eA subsequent CT scan demonstrated multiple enlarged and necrotic lymph nodes in the retroperitoneum. Further evaluation with contrast-enhanced CT revealed an irregular space-occupying lesion within the right kidney, suggestive of renal pelvic carcinoma (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).The patient was started on sensitive antibiotic therapy to address the infection. Definitive treatment planning will be determined following adequate control of the infection.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWhile radical nephroureterectomy remains the standard treatment for UTUC, this patient presents unique challenges. The presence of left renal atrophy means that radical resection of the right kidney (the affected side) carries a significant risk of requiring lifelong dialysis. Furthermore, preoperative imaging revealed suspicious lymph node involvement, suggestive of advanced UTUC. In accordance with the 2023 EAU (European Association of Urology) Guidelines regarding renal function preservation strategies for advanced UTUC, the risks and benefits were thoroughly discussed with the patient and family. Ureteroscopic biopsy was deemed high-risk due to severe hydronephrosis and pyonephrosis; thus, a percutaneous approach was preferred for combined tumor resection and stone clearance.Following this informed consent process, the decision was made to proceed with \"percutaneous resection of the renal mass via electrocautery combined with percutaneous nephrolithotomy (PCNL)\". The goals of this procedure are threefold: 1) to obtain definitive histopathological diagnosis of the tumor nature, 2) to prepare for subsequent adjuvant therapy, and 3) to simultaneously clear the right renal calculi.\u003c/p\u003e \u003cp\u003eFollowing the induction of effective anesthesia, the patient was placed in the lithotomy position. The surgical field was prepared and draped sterilely. An F8/9.8 ureteroscope was inserted into the bladder.No obvious abnormalities were observed within the bladder lumen.\u003c/p\u003e \u003cp\u003eThe patient was then repositioned into the prone position. The surgical field was re-prepped and draped sterilely. Under ultrasound guidance, the right renal collecting system was accessed via puncture through the right 11th intercostal space.Urine return was confirmed, and a guidewire was inserted. A small scalpel was used to make a 0.5 cm skin incision. The tract was dilated over the guidewire using an F24 dilator, and an F24 working sheath was placed.\u003c/p\u003e \u003cp\u003eThe ureteroscope was introduced through the sheath into the renal collecting system.Multiple papillary masses and calculi were visualized within the renal pelvis. The urine appeared turbid with abundant flocculent debris. Stones were found impacted at the calyceal necks.Holmium laser lithotripsy was employed to fragment the impacted stones, which were then flushed out via hydrostatic pressure irrigation.Copious purulent discharge was noted during the procedure.The ureteral catheter was removed. An F5 double-J ureteral stent was inserted antegradely over the guidewire.A GYRUS PK (Plasmakinetic) bipolar resectoscope was then introduced through the F24 working sheath into the renal pelvis. Using the PK cutting loop, the raised tumor masses were partially resected, and the specimens were sent for pathological examination. The resection bed was thoroughly cauterized for hemostasis using the resectoscope electrode.Upon inspection confirming no active bleeding points, the resectoscope was withdrawn. An Foley catheter was inserted through the nephrostomy tract to serve as a right nephrostomy tube. The balloon was inflated with 3 ml of sterile water.\u003c/p\u003e \u003cp\u003eAnesthesia was maintained effectively throughout the procedure. The surgery proceeded smoothly without significant hemorrhage. The patient was transported to the recovery room in stable condition upon completion of the operation.\u003c/p\u003e \u003cp\u003eFor patients with muscle-invasive urothelial carcinoma, the standard systemic chemotherapy regimens are typically\"MVAC\" (Methotrexate, Vinblastine, Doxorubicin, Cisplatin)or\"GC\" (Gemcitabine, Cisplatin).Although the MVAC regimen can be highly effective, it is associated with a higher toxicity profile. Given the patient's relatively poor general condition, the GC regimen was selected as the preferred treatment option.\u003c/p\u003e \u003cp\u003eThe patient has now completed one cycle of GC chemotherapy. Follow-up imaging with chest CT and contrast-enhanced abdominal CT showed no evidence of disease progression in terms of the maximum tumor diameter or the areas of necrotic retroperitoneal lymph nodes. Tumor marker levels also showed no significant elevation.\u003c/p\u003e \u003cp\u003eThe patient's serum creatinine levels have remained stable within the range of 126.5\u0026ndash;139.6 \u0026micro;mol/L.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eHSK is a rare congenital renal fusion anomaly. Epidemiological studies indicate a prevalence of approximately 0.25% in the general population [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], with a male-to-female ratio of about 2:1 [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Its formation is likely the result of the fusion of the two umbilical arteries during early embryonic development [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].The anatomical anomalies associated with HSK encompass several aspects:Vascular Variations:Aberrant vasculature, including blood supply variations. These variant vessels may originate from the inferior mesenteric artery, abdominal aorta, contralateral renal artery, common iliac artery, and internal iliac artery [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].Ureteral Course:The two renal moieties are connected by an isthmus, which causes the ureters to pass ventrally over it, potentially leading to compression.Renal Rotation:Malrotation results in the renal hila facing anteriorly (ventrally).This abnormal anatomical position frequently leads to impaired urinary drainage, constituting a significant cause of chronic urinary tract obstruction. This obstruction is also a contributing factor to the high incidence of nephrolithiasis in HSK patients.\u003c/p\u003e \u003cp\u003eUTUC accounts for a small proportion (5%-10%) of all urothelial carcinomas. While no established direct association between HSK and UTUC is known, some reports suggest that the incidence of renal pelvic carcinoma in HSK patients is at least three times higher than in the general population. This increased occurrence is often attributed to chronic noxious stimuli related to infection, urinary stasis, and calculi; however, the precise pathological mechanisms remain unclear. Japanese researchers reviewed 24 previously reported cases of renal pelvic tumors in HSK. Seven of these cases (30%) contained a squamous cell carcinoma component[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The renal pelvic tumor in our patient also presented as an invasive high-grade urothelial carcinoma with squamous differentiation, suggesting that squamous differentiation may be associated with chronic inflammation inherent to the HSK environment. The squamous differentiation observed in our case aligns with the hypothesis that chronic inflammation secondary to urinary stasis and calculi in HSK may drive metaplastic changes.\u003c/p\u003e \u003cp\u003eDistinguishing whether an invasive renal mass is of urothelial or renal cortical origin can be difficult. This distinction is critical for treatment planning. Renal cortical tumors typically necessitate radical nephrectomy or partial nephrectomy. Conversely, urothelial carcinoma originating from the renal pelvis mandates radical nephroureterectomy(removal of the entire upper urinary tract, including kidney, ureter, and bladder cuff). A study by Yasuda et al. [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] examining pathology in 49 HSK patients with renal masses found only 27 (55%) were renal cell carcinoma (RCC), while 22 (45%) were benign. This highlights that partial nephrectomy offers significant functional advantages for HSK patients with renal masses. The incidence of RCC appears lower than expected in HSK, with benign and non-invasive tumors being relatively common.\u003c/p\u003e \u003cp\u003eMultiphasic CT is an excellent tool for differentiating tumor types.However, biopsy or positive urine cytology is still recommended to confirm the diagnosis. While ureteroscopic biopsy can be used for confirmation, it has been associated with an increased risk of intravesical recurrence[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWe employed percutaneous tumor resection via electrocautery for this patient. This approach offered multiple benefits:Ensured adequate tissue sampling, minimizing the risk of false-negative pathological results.Provided a cytoreductive effect and achieved effective hemostasis.Simultaneously allowed removal of the renal calculi, thereby resolving the obstruction-induced urinary tract infection.Prepared the patient for subsequent adjuvant therapy.Treatment Rationale Based on Potential Pathology:Had the postoperative pathology indicated a RCC,partial nephrectomy could have been performed. This strategy would have avoided the need for long-term postoperative dialysis. This approach has been previously reported in cases of HSK associated with renal tumors [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Furthermore, Latif et al. [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]reported a case of robot-assisted radical surgery in an HSK patient with normal bilateral renal function who did not require postoperative dialysis.\u003c/p\u003e \u003cp\u003eHowever, the postoperative pathology in this case confirmed urothelial carcinoma. Standard radical surgery for UTUC mandates right radical nephroureterectomy with excision of the bladder cuff.Given the patient's left renal atrophy, this radical surgery would have resulted in lifelong dialysis dependency. Additionally, the presence of suspected lymph node metastasis indicated advanced disease.\u003c/p\u003e \u003cp\u003eAfter thoroughly discussing the disease status, prognosis, and treatment options with the patient, the decision was ultimately made to proceed with the GC chemotherapy regimen as adjuvant therapy.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eStatements\u003c/strong\u003e\u003c/p\u003e\u003cp\u003eWritten informed consent was obtained from the patient for publication of this case report and any accompanying images.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgement (optional)\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interest Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors have no conflicts of interest to declare.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding Sources\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eGrants from the research project at Qingdao University (YLJT20231002).The funders had no role in this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLY,YZ,YT and YW analyzed and interpreted the patient data and drafted the paper. LY and YW contributed equally to this work.ZZ,XH,ZM,JY,QL conceptualized the study and design, analysis, and interpretation of data. All authors contributed to the article and approved the submitted version.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analyzed during this study are included in this article. Further inquiries can be directed to the corresponding author.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWritten informed consent for publication of their clinical details and clinical images was obtained from the patient parents. A copy of the consent form is available to the Editor of this journal.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eTkocz M, Kupajski M. Tumour in horseshoe kidney\u0026mdash;different surgical treatment shown in five example cases. Contemp Oncol (Pozn). 2012;16(3):254-257.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eSoria F, Shariat SF, Lerner SP, et al. Epidemiology, diagnosis, preoperative evaluation and prognostic assessment of upper-tract urothelial carcinoma (UTUC).\u0026nbsp;World Journal of Urology, 2017, 35(3): 379\u0026ndash;387.\u003c/li\u003e\n \u003cli\u003eHouat AP, Guimaraes CTS, Takahashi MS, Rodi GP, Gasparetto TPD, Blasbalg R, et al. Congenital anomalies of the upper urinary tract: A comprehensive review.\u0026nbsp;Radiographics, 2021, 41: 462\u0026ndash;486. doi: 10.1148/rg.2021200078.\u003c/li\u003e\n \u003cli\u003eSchiappacasse G, Aguirre J, Soffia P, et al. CT findings of the main pathological conditions associated with horseshoe kidneys.\u0026nbsp;British Journal of Radiology, 2015, 88: 20140456. doi: 10.1259/bjr.20140456.\u003c/li\u003e\n \u003cli\u003eMajos M, Polguj M, Szemraj-Rogucka Z, et al. The level of origin of renal arteries in horseshoe kidney vs. in separated kidneys: CT-based study.\u0026nbsp;Surgical and Radiologic Anatomy, 2018, 40: 1185\u0026ndash;1191. doi: 10.1007/s00276-018-2071-8.\u003c/li\u003e\n \u003cli\u003eMizusawa H, Komiyama I, Ueno Y, et al. Squamous cell carcinoma in the renal pelvis of a horseshoe kidney.\u0026nbsp;International Journal of Urology, 2004, 11(9): 782\u0026ndash;784.\u003c/li\u003e\n \u003cli\u003eYasuda Y, Zhang JJ, Attawettayanon W, et al. Pathologic findings and management of renal mass in horseshoe kidneys.\u0026nbsp;Urology, 2022, 166: 170\u0026ndash;176. doi: 10.1016/j.urology.2022.03.020.\u003c/li\u003e\n \u003cli\u003eGuo RQ, Hong P, Xiong GY, et al. Impact of ureteroscopy before radical nephroureterectomy for upper tract urothelial carcinomas on oncological outcomes: a meta-analysis.\u0026nbsp;BJU International, 2017, 121(2): 184\u0026ndash;193. doi: 10.1111/bju.14053.\u003c/li\u003e\n \u003cli\u003eQuintana \u0026Aacute;lvarez R, Herranz Amo F, Bueno Chom\u0026oacute;n G, et al. Surgical management of horseshoe kidney tumors: Literature review and analysis of two cases.\u0026nbsp;Actas Urol\u0026oacute;gicas Espa\u0026ntilde;olas (English Edition), 2021, 45(7): 493\u0026ndash;497.\u003c/li\u003e\n \u003cli\u003eLatif ER, Ahmed I, Thomas M, Eddy B. Robotic nephroureterectomy in a horseshoe kidney for upper tract urothelial carcinoma. BMJ Case Reports, 2021, 14(6): e234901. doi: 10.1136/bcr-2020-234901.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-urology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"buro","sideBox":"Learn more about [BMC Urology](http://bmcurol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/buro/default.aspx","title":"BMC Urology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Horseshoe kidney, urothelial carcinoma, urolithiasis, renal atrophy, minimally invasive surgery, chemotherapy","lastPublishedDoi":"10.21203/rs.3.rs-6774249/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6774249/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eHorseshoe kidney (HSK) is a rare congenital anomaly with an incidence of approximately 0.25% in the general population. The unique anatomical structure of HSK often leads to vascular and excretory abnormalities, complicating the diagnosis and management of coexisting diseases. We present a rare case of a 46-year-old male with HSK who was simultaneously diagnosed with urothelial carcinoma, urolithiasis, and renal atrophy. Given contralateral renal atrophy, radical nephrectomy was contraindicated to avoid lifelong dialysis. Instead, a percutaneous approach was employed to excise the renal mass and remove the kidney stones in a single session. Postoperative pathology confirmed high-grade urothelial carcinoma with squamous differentiation. Adjuvant chemotherapy with the Gemcitabine-Cisplatin (GC) regimen was initiated, and the patient showed no significant adverse effects after one cycle. This case highlights the challenges in managing complex pathologies in HSK and underscores the importance of minimally invasive techniques and multidisciplinary approaches in advanced cases.\u003c/p\u003e","manuscriptTitle":"Triple Pathology in a Horseshoe Kidney: A Rare Case of Concurrent Urothelial Carcinoma, Urolithiasis, and Renal Atrophy with Analysis of Multimodal Management","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-08 05:57:09","doi":"10.21203/rs.3.rs-6774249/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2025-08-01T21:46:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"46397369026087280228393744650426169819","date":"2025-07-23T09:32:22+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-19T07:13:35+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-10T12:23:20+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"303039293388618201262327320221153081264","date":"2025-07-10T12:06:13+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"110031251650255078316844788042644173826","date":"2025-07-06T16:09:16+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"192510217257043023174736480503042098082","date":"2025-07-04T18:11:29+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-07-03T09:22:36+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-06-04T19:08:37+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-05-31T13:25:31+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-05-31T13:23:00+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Urology","date":"2025-05-29T07:59:30+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-urology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"buro","sideBox":"Learn more about [BMC Urology](http://bmcurol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/buro/default.aspx","title":"BMC Urology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9f0063b0-a6d6-4565-9efa-1e39701ce0d4","owner":[],"postedDate":"July 8th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-07-08T05:57:09+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-08 05:57:09","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6774249","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6774249","identity":"rs-6774249","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}