Tumor in the Horseshoe Kidney: Clinical Implications and Review of Embryogenesis

Abstract

We report on 3 patients with tumor in a horseshoe kidney, 1 of whom had bilateral tumor (renal cell cancer on the right side and urothelial cancer on the left side). Tumors that arise predominantly in the bridge of a horseshoe kidney can mimic the symptoms of an intra-abdominal disease process. Besides routine diagnostic procedures, angiography is essential to plan the surgical approach, which in principle should be organ-sparing. The literature of the embryology of the horseshoe kidney was reviewed for a relationship between the abnormal renal development and the site of tumorigenesis, and for development of a key for the wide variation of blood supply. Recently reported data suggest that the theory of a mechanical fusion is valid only for horseshoe kidneys with a fibrous isthmus but that an abnormal migration of the posterior nephrogenic area causes the majority of horseshoe kidneys in which the isthmus consists of parenchyma. Development of the isthmus through abnormal migration could predispose this location for renal cell cancer and would explain the varying forms of blood supply. Additionally, this hypothesis supports the previously raised assumption that horseshoe kidneys may be the result of teratogenic factors, which also may be responsible for the known increased incidence of related congenital anomalies and of nephroblastoma.

Sonographic features of horseshoe kidney: review of 34 patients.

“…Horseshoe kidney also is associated with a twofold increased relative risk of Wilms tumor, a threefold to fourfold increased relative risk of transitional cell carcinoma, and a markedly increased relative risk (62-fold) of primary renal carcinoid tumors. 11,12 Wilms tumor has a surprising predilection to originate in the isthmus. 13 In recent years, ultrasonography has become the first imaging procedure performed in the evaluation of pathologic urinary tract conditions.…”

Incidence of Tumoural Pathology in Horseshoe Kidneys

“…Since then, some 30 more cases were described individually. The coexistence of a transitional carcinoma and a renal adenocarcinoma in the same HK was described on two opportunities [5], as well as sarcomas [6], renal pelvis cholesteatomas [7], teratomas [8], oncocytomas [9] and nephroblastomatosis [2]. …”

“…At our centre, only 1 out of 5 affected the isthmus. Its incidence among the HK cases is not greater than among the normal population [5]. Its prognosis is not related to its association with HKs but is determined by the cellular degree and the stage [12].…”

“…Presently, to perform a CT scan [14] is considered essential within the diagnostic protocol, and it is recommended to carry out an arteriography prior to surgery [5, 12]. Due to our experience, we have been able to verify the complexity of oncologic surgery of HKs.…”

The minimally invasive management of ureteropelvic junction obstruction in horseshoe kidneys

“…[1] Although most horseshoe kidneys are asymptomatic, individuals with this anomaly have an incidence of ureteropelvic junction obstruction (UPJO) of 15-33%. [2] The increased incidence of UPJO may be related to several factors including the high insertion of the ureter into the renal pelvis, the anatomic relation of the ureter to the isthmus, and the highly variable blood supply to the kidney.…”