Crossed Unfused Ectopic Pelvic Kidneys: A Case Illustration

Abstract

Crossed unfused ectopia constitutes a very rare variant of ectopic kidneys, with an approximate incidence of 1 : 75000. We hereby describe a rare case of an incidental finding of crossed unfused ectopic kidneys, in a 45-year-old gentleman incidentally found to have a bladder lesion. The unique blood supply of his kidneys has also been described. The present case also highlights the different subtypes of renal ectopia, the different embryological hypotheses behind their presentation, and the various systematic anomalies, associated with them. Variations in vasculature of ectopic kidneys have been only described in case reports and are crucial to recognize in case any further intervention is needed.

A Rare Case of Crossed Non-fused Ectopic Kidney

“…In this type of renal ectopia, the ureters remain uncrossed and normally insert into the bladder. The crossed-over kidney may fuse to the orthotopic kidney, leading to the more common crossed-fused ectopia (type A in the McDonald and McClellan classification), with an incidence of 1:2000 autopsies; or remain unfused, leading to a rare non-fused subtype, of CRE (type B), with an incidence of 1:75000 autopsies [ 5 ]. CRE is more common in males, and left-to-right-sided crossed ectopia occurs thrice as frequently as right-to-left-sided, as present in our study [ 6 ].…”

“…CRE is more common in males, and left-to-right-sided crossed ectopia occurs thrice as frequently as right-to-left-sided, as present in our study [ 6 ]. Other variants of CRE include solitary CRE (type C) and non-fused bilateral CRE (type D), which are very infrequently encountered in clinical practice [ 5 ].…”

“…The genetic theory links mutations in the sonic hedgehog (SHH) gene to the development of CRE, which supports that CRE is observed in identical twins and siblings of the same family [ 8 ]. The ureteral theory of ectopia proposes that a wandering ureteral bud diffuses with the contralateral metanephric blastema after crossing the midline, leading to a crossed ectopic kidney [ 5 ]. According to this theory, the other blastema, which did not fuse with the ureteral bud, eventually regresses.…”

“…Non-fused CRE can present clinically in different ways. It may be discovered incidentally during investigations for another disease [ 5 , 10 ]. It can also present with urinary symptoms due to UTIs [ 11 ] or an abdominal mass leading to abdominal pain or constipation [ 3 , 12 ].…”