# Unfused Crossed Renal Ectopia With Aberrant Vasculature: A Case Report

## TL;DR

An 80-year-old man with bladder cancer was found to have a rare kidney condition called unfused crossed renal ectopia, which was previously misdiagnosed as a missing kidney.

## Contribution

This case report highlights the importance of recognizing unfused crossed renal ectopia and its aberrant vasculature for proper medical management.

## Key findings

- The patient was diagnosed with unfused crossed renal ectopia, a rare and often asymptomatic condition.
- Aberrant vascularization was identified, which is critical to consider before surgical or radiation therapy.

## Abstract

An 80‐year‐old man presenting with gross hematuria was diagnosed with muscle‐invasive bladder cancer. Ten years prior, based on an ultrasound performed for chronic renal insufficiency, he was told he had a congenitally absent left kidney. Office cystoscopy showed a large bladder tumor. Following cystoscopy, he underwent a CT‐urogram. This study showed that he, in fact, had left‐to‐right unfused crossed renal ectopia. Unfused crossed renal ectopia is an extremely rare abnormality that is usually asymptomatic and typically incidentally diagnosed. Crossed renal ectopia is a result of improper migration of the metanephric blastema and ureteric bud development resulting in a contralateral ectopic kidney with aberrant vascularization. The ureter crosses the midline and inserts into the orthotopic side of the bladder. Special consideration of the vascularization of unfused crossed ectopic kidneys is necessary prior to surgery or radiation therapy.