Renal cell carcinoma in a horseshoe kidney: radiology and pathology correlation

Partial nephrectomy of a horseshoe kidney associated with renal cell carcinoma and ureteral stone: A clinical case report

Key Clinical Message

Although anatomical and vascular abnormalities of the horseshoe kidney might be challenging, complete preoperative imaging evaluations and accurate organ-sparing surgical planning can lead to much lower complications.

Abstract

Horseshoe kidney (HK) is one of the most common renal fusion anomalies. Renal carcinoids are rarely reported in HK patients. Here, we described a rare case of advanced right renal cell carcinoma (RCC) along with proximal left ureter stone in a 41-year-old man who presented with a complaint of turbid urine. Early blood tests revealed a blood urea nitrogen of 44 mg/dL and serum creatinine of 1.35 mg/dL. The urine analysis showed microscopic hematuria (6-8 RBCs) and few calcium oxalate crystals. The imaging evaluations revealed an HK anomaly with a solid mass on the right side and a 4 mm stone in the proximal left ureter. The findings suggested RCC which was confirmed by histopathology examination. Consequently, the patient was scheduled for an organ-preserving open surgery of a right kidney tumor with concomitant left ureterolithotomy. The 16-month follow-up showed no urological complications, metastasis, or tumor proliferation. Although the anatomical and vascular abnormalities of HK might be challenging, organ-sparing surgical treatment should be considered in feasibly resectable tumors. Complete preoperative imaging evaluations to identify the characteristics of HK, as well as accurate surgical planning, can lead to much lower complications.

Horseshoe kidney: Morphologic features, embryologic and genetic etiologies, and surgical implications

The horseshoe kidney (HSK) is the most common congenital abnormality of the upper urinary tract with an incidence of approximately 1 in 500 in the general population. Although individuals with HSK are often asymptomatic, they are at increased risk for neoplasms, infections, ureteropelvic obstruction secondary to lithiasis or vascular compression. Direct injury from trauma is increased in these individuals as is the risk of intraoperative complications secondary to damage involving the typically complex renal or adrenal vascular supply. We briefly review etiological factors including renal and urinary system embryology, genetic mutations, abnormalities related to faulty cell signaling, aberrant cell migration, and other possible causes including environmental exposures and trauma. In addition, we call attention to factors that might influence the success of surgical procedures in patients with HSK. We argue that an understanding of possible etiologies of the HSK and its different subtypes may be useful when planning surgical procedures or considering risk-benefit ratios associated with different surgical options. We briefly present the organization of a HSK in a 100-year-old male demonstrating an unusual vascular supply discovered during a dissection laboratory session in a medical school anatomy course. We describe the structure of the HSK, the position and relationships of the HSK to other structures within the abdomen, and the associated vascular relationships.

Horseshoe kidney with PLA2R-positive membranous nephropathy

Background

Horseshoe kidney (HSK) is a common congenital defect of the urinary system. The most common complications are urinary tract infection, urinary stones, and hydronephrosis. HSK can be combined with glomerular diseases, but the diagnosis rate of renal biopsy is low due to structural abnormalities. There are only a few reports on HSK with glomerular disease. Here, we have reported a case of PLA2R-positive membranous nephropathy occurring in a patient with HSK.

Case presentation

After admission to the hospital due to oedema of both the lower extremities, the patient was diagnosed with nephrotic syndrome due to abnormal 24-h urine protein (7540 mg) and blood albumin (25 g/L) levels. Abdominal ultrasonography revealed HSK. The patient’s brother had a history of end-stage renal disease due to nephrotic syndrome. Therefore, the patient was diagnosed with PLA2R-positive stage II membranous nephropathy through renal biopsy under abdominal ultrasonography guidance. He was administered adequate prednisone and cyclophosphamide, and after 6 months of treatment, urinary protein excretion levels significantly decreased.

Conclusion

The risk and difficulty of renal biopsy in patients with HSK are increased due to structural abnormalities; however, renal biopsy can be accomplished through precise positioning with abdominal ultrasonography. In the literature, 20 cases of HSK with glomerular disease have been reported thus far. Because of the small number of cases, estimating the incidence rate of glomerular diseases in HSK is impossible, and the correlation between HSK and renal pathology cannot be stated. Further studies should be conducted and cases should be accumulated to elucidate this phenomenon.

Pediatric Papillary Renal Cell Carcinoma in a Horseshoe Kidney: A Case Report with Review of the Literature

Renal cell carcinoma is the most common malignancy of the kidney in adults. In children, however, it only accounts for an estimated 1.8 to 6.3% of all pediatric malignant renal tumors. Papillary renal cell carcinoma is the second most common type of renal cell carcinoma in children. We present the case of a 12-year-old boy with a 2-month history of abdominal pain, unexplained weight loss, and gross hematuria. Computed tomography revealed a horseshoe kidney and a well-defined mass of 4 cm arising from the lower pole of the right kidney. Microscopically the tumor was composed of papillae covered with cells with abundant eosinophilic cytoplasm and high-grade nuclei with prominent nucleoli. Immunohistochemistry was performed; EMA, Vimentin, and AMACR were strongly positive while CK7, CD10, RCC antigen, TFE3, HMB-45, and WT-1 were negative. Currently, 10 months after the surgical procedure, the patient remains clinically and radiologically disease-free.

A Rare Case of a Renal Cell Carcinoma Confined to the Isthmus of a Horseshoe Kidney

Horseshoe kidney (HSK) is the most common renal anomaly. Reports of the incidence of renal cell carcinoma (RCC) in HSK are conflicting. Very few cases of isthmus-located RCC have been reported in the literature. We report a unique case of an isthmus-located RCC. Proper vascular and tumor imaging prior to surgery is key to successful tumor removal.

Follow-up (99m)Tc EC renal dynamic scintigraphy and DMSA-III SPECT/CT in unmasking a masqueraded case of Horseshoe kidney

Hydronephrosis is a common finding in urinary tract outflow obstruction. Chronically obstructed hydronephrotic system may be associated with parenchymal changes. Ultrasound, intravenous urography, micturating cysto-urethrogram and scintigraphy are commonly performed to evaluate the cause of obstruction. In childhood, pelviureteric junction obstruction is a common cause of the hydronephrosis. Hydronephrosis can also be present in horseshoe kidneys due to poor drainage. However, a large sized hydronephrotic cavity may obscure the finding of horseshoe kidney. A case was reported, and it was diagnosed as horseshoe kidney on follow-up renal dynamic scan and confirmed with the help of dimercaptosuccinic acid SPECT/CT.

Primary leiomyosarcoma of a horseshoe kidney in a woman with Turner syndrome: a case report

Background

Turner syndrome is characterized by complete or partial X-chromosome monosomy and has various clinical features, including horseshoe kidney. Leiomyosarcoma is an extremely rare tumor that accounts for only 0.1% of all invasive renal tumors.

Case presentation

A 50-year-old Japanese woman presented at a community hospital with a chief complaint of abdominal pain. Computed tomography revealed a horseshoe kidney with a hypovascular tumor (size, 9 × 7 cm) showing calcification in the upper pole of the right kidney. Open right heminephrectomy and division of the isthmus were performed. Histological examination revealed alternating fascicles of spindle cells with blunt ended non-tapering nuclei and eosinophilic cytoplasm. The tumor had high mitotic activity with a mitotic count of 8 mitoses/10 high-power fields. On the basis of these findings, we diagnosed the patient as having leiomyosarcoma.

Conclusion

Primary leiomyosarcoma of the horseshoe kidney in a patient with Turner syndrome is a very rare occurrence.

Horseshoe kidney mimicking cross-fused ectopia on (99m)Tc-EC renal dynamic scintigraphy

The ‘horseshoe kidney’ is the most common renal fusion anomaly. In this disorder, two developed kidneys are connected to each other at the lower part and grow together. We report a case of horseshoe kidney mimicking cross-fused ectopia in ^99mTc-EC renal dynamic scintigraphy.