What is the next step for a 64-year-old woman with a horseshoe kidney and a suspected large urothelial cell tumor in the left upper pole?

Management of Suspected Urothelial Cell Tumor in a Horseshoe Kidney

For a 64-year-old woman with a horseshoe kidney and suspected large urothelial cell tumor in the left upper pole, the next step should be a comprehensive diagnostic evaluation including CT urogram or retrograde pyelogram with ureteroscopy and biopsy to confirm diagnosis before proceeding to nephroureterectomy with bladder cuff and regional lymphadenectomy.

Initial Diagnostic Workup

• CT urogram or retrograde pyelogram with ureteroscopy is essential to evaluate the suspected urothelial tumor in the upper pole of the horseshoe kidney 1
• Chest radiograph to evaluate for possible metastatic disease and assess comorbid conditions 1
• Urine cytology to help identify carcinoma cells 1
• Complete hematologic, renal, and hepatic function evaluation 1
• Additional imaging studies (bone scan) may be needed if indicated by initial test results or specific symptoms 1

Diagnostic Considerations in Horseshoe Kidney

• Horseshoe kidney is the most common congenital renal fusion anomaly affecting 1 in 400-600 patients 2
• Aberrant vascular anatomy in horseshoe kidneys requires careful preoperative planning 3
• Angiography is essential to plan the surgical approach in horseshoe kidneys with tumors 4
• Endoscopic assessment should confirm no other foci of disease 2

Treatment Approach

For High-Grade Tumors (Most Likely Scenario)

• Nephroureterectomy with a cuff of bladder and regional lymphadenectomy is the standard treatment for high-grade upper tract urothelial tumors 1
• In horseshoe kidneys, this involves splitting the isthmus and saving the contralateral moiety 3
• The procedure can be performed using minimally invasive techniques (robotic or laparoscopic) when feasible 2, 5
• Regional lymphadenectomy should be performed for high-grade tumors 1

For Well-Differentiated Tumors (If Confirmed by Biopsy)

• Nephron-sparing options may include:
  • Transureteroscopic approach 1
  • Percutaneous approach with or without postsurgical intrapelvic chemotherapy or BCG 1

Post-Treatment Follow-up

• For pathologic stage pT0 or pT1:

  • Serial cystoscopies at 3-month intervals for the first year, then every 6 months 1
  • Upper-tract imaging studies (IVP, retrograde pyelogram, CT or MRI urography) at 1-2 year intervals 1
  • Consider ureteroscopy at 3-12 month intervals if endoscopic resection was performed 1

• For pathologic stage pT2, pT3, pT4, or nodal disease:

  • Consider adjuvant chemotherapy 1
  • Serial evaluations of the urothelial tract 1
  • Imaging studies to exclude metastatic disease 1

Important Considerations and Pitfalls

• Horseshoe kidneys present unique challenges due to aberrant vascular anatomy and risk of renal insufficiency 3
• Preservation of renal function is critical, with functional advantage observed for nephron-sparing surgery when feasible 3
• Tumors in horseshoe kidneys can mimic intra-abdominal disease processes, particularly when arising in the isthmus 4
• Careful preoperative planning is essential due to the variable blood supply patterns in horseshoe kidneys 4
• In cases where nephroureterectomy is performed, a portion of the bladder must be removed to ensure complete removal of the entire intramural ureter 1