Transitional cell carcinoma in a fused crossed ectopic kidney.

Nephroureterectomy is considered the reference standard treatment for invasive transitional cell carcinoma of the ureter. When this malignancy occurs in a patient with renal fusion anomaly, separating the involved kidney from its conjoint mate becomes a challenging task for the surgeon. We report a unique case in which a patient with an L-shaped left-to-right crossed ectopic kidney was diagnosed with invasive ureteral transitional cell carcinoma. The preoperative assessment in these uncommon cases should include renal angiography or computed tomography angiography to provide key information about the renal vasculature, which is essential for planning the surgical dissection and line of separation between the kidneys.