Malignancy of a Horseshoe Kidney: A Case Series with a Rare Presentation

Horseshoe kidney is the most common fusion anomaly. Patients with horseshoe kidney typically present with symptoms related to infection, stone formation, and hydronephrosis. Rarely, patients may present with malignancy of horseshoe kidney, and most of them arise from isthmus. We are presenting a case series of 2 cases of renal cell carcinoma arising from horseshoe kidney. KEYWOrDs: Clear-cell carcinoma, fusion anomaly, horseshoe kidney, papillary-cell carcinoma, renal cell carcinoma cOrrEsPONDENcE: Sameer Trivedi, Associate Professor Mch, DNB, Department of Urology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India, 221005 (drsameertrivedi@gmail.com) cItAtION: UroToday Int J. 2012 December;5(6):art 70. http://dx.doi. org/10.3834/uij.19445784.2012.12.15 UroToday International Journal® ©2012 Digital Science Press, Inc. UIJ / Vol 5 / Iss 6 / December / http://dx.doi. org/10.3834/uij.1944-5784.2012.12.15 http://www.urotodayinternationaljournal. com ISSN 1944-5792 (print), ISSN 1944-5784 (online) On physical examination, an ill-defined lump 7 cm x 5 cm was palpable in the upper right quadrant involving the right lumbar and umbilical regions. The baseline blood investigations were within the normal limit. His urine examination revealed 30-35 RBC/HPF. An ultrasonography of the abdomen indicated the presence of HSK with a mass approximately 7 cm x 6 cm arising from the upper pole of the right renal moiety. The multidetecting computer tomography (CT) scan confirmed the presence of an HSK with fusion at the lower pole, an enhanced lesion of 7.3 cm x 7 cm arising from the upper pole of the right renal moiety, and areas of calcification and necrosis suggestive of RCC (Figure 1). The metastatic work-up, which included a chest X-ray and liver function test, was normal. On exploration, HSK with a well-formed isthmus connecting the lower pole of both kidneys with a mass arising from the upper pole of the right renal moiety was seen. No significant lymphadenopathy was noticed (Figure 2). The patient underwent right radical nephrectomy with isthmectomy by the right subcostal transperitoneal approach. Intraoperatively, the finding of a HSK with a mass arising from the right upper pole was confirmed. A well-formed isthmus was found connecting to the lower pole. The stump of the isthmus was run under with an absorbable running suture, and then it was covered with an omental patch to prevent hemorrhage and urinary fistula INtrODUctION Horseshoe kidney (HSK) is the most common fusion anomaly, with an incidence rate of 1 in 400 of the general population [1]. While most of the reported cases are incidental findings, sometimes a patient may present with pictures of hydronephrosis, infection, and calculus formation [2]. Rarely, a patient presents with malignancy of the renal unit. Hildebrand, in 1895, is credited with reporting the first case of malignancy of HSK [3]. Most of these malignancies were arising from isthmus of HSK [4], and the majority of these were of the clear-cell variety. We are reporting here 2 cases of renal cell carcinoma (RCC), including a very rare case of the papillary-cell variety arising from the upper pole.