Background: Horse shoe kidney is rare, rarer is urothelial carcinoma of renal pelvis in horse shoe kidney, but is more common than that in normal kidney. Radical nephroureterectomy with removal of a cuff of urinary bladder is the standard of treatment. Despite of complete surgery, there are loco-regional recurrences. Case Report: Presenting a case of 60-year male with gross hematuria of 2 months. On imaging found to have horse show kidney with right kidney upper pole mass, believing it to be renal cell carcinoma, nephrectomy was done. However, histopathology turned out to be low-grade urothelial carcinoma of pelvis. Patient had recurrence in left over ureteral stump and ureteric orifice after 10 months. Completion surgery followed by adjuvant intra-vesical bacille calmette guerin (BCG) was given and patient has no recurrence since past 2 years. Conclusion: Urothelial carcinoma of renal pelvis although rare, but it is three to four times more common than that in normal kidney due to chronic obstruction in horse shoe kidney. Due to multifocality of urothelial carcinoma of renal pelvis, gold standard treatment remains complete nephroureterectomy with removal of a cuff of urinary bladder. Post-operative locoregional recurrences are seen and judicious use of intravesical BCG, chemotherapy, and radiotherapy has shown to beneficial.

Keywords: Horseshoe kidney, fused Kidney, urothelial cell carcinoma of upper ttract, transitional cell carcinoma nephroureterectomy, case report