The Rarest of the Rare: Crossed Fused Renal Ectopia of the Superior Ectopia Type

Abstract

Crossed fused renal ectopia is a rare congenital anomaly of the urinary system where one kidney crosses over to opposite side and the parenchyma of the two kidneys fuse. Herein, we present an atypical CFRE case whose renal anatomy does not exactly match any of the already defined CFRE types. Both of the kidneys are ectopic with the crossed ectopic right kidney lying superiorly and fused to the upper pole of the left kidney. Renal arteries were originating from the common iliac arteries. A focal 90% stenosis was observed on the right main renal artery. The patient is borderline hypertensive.

Crossed Fused Renal Ectopia with Renal Calculus and Gross Hydronephrosis- A Case Report

“…Resulting from aberrant migration and crossing of the midline of the metanephric blastema and ureteral bud, CFRE is thought to develop during 4 th to 8 th weeks of gestation. Mostly remaining asymptomatic and detected as an incidental finding during imaging studies, six well-defined anatomical variations of CFRE have been reported [2]. We report here one such case of crossed fused renal ectopia detected by usg, which was later on confirmed by computed tomography Keywords: CFRE; MDCT; Hydronephrosis …”

Crossed Unfused Ectopic Pelvic Kidneys: A Case Illustration

“…Crossed renal ectopia is a rare entity detected incidentally in 20 to 30% of cases [ 4 ] and results from the aberrant migration and crossing of the midline by the metanephric blastema and the ureteral bud [ 5 ], usually occurring during the fourth to eighth week of gestation [ 5 ]. Despite the ectopic position of the kidneys, the ureters are not crossed and insert normally into the bladder [ 4 ].…”

“…Second in incidence after horse-shoe kidney [ 5 ], with male-to-female predominance of 1.4 to 2 : 1, with two to three times higher chance to have a left-to-right ectopy [ 7 ], CRE is further categorized into four subcategories: crossed fused renal ectopia (CFRE), unfused ectopia, solitary CRE, and unfused bilateral CRE [ 4 ]. Among the four subcategories, those with fusion represent the majority of cases, around 90% [ 4 ], with an incidence of 1 in 2000 [ 6 ], followed by the unfused form with an incidence of 1 : 75000 [ 5 ]. There are 6 subtypes of CFRE: inferior, sigmoid or S-shaped, lump, disc, L-shaped, and superior CRFE [ 5 ].…”

“…Among the four subcategories, those with fusion represent the majority of cases, around 90% [ 4 ], with an incidence of 1 in 2000 [ 6 ], followed by the unfused form with an incidence of 1 : 75000 [ 5 ]. There are 6 subtypes of CFRE: inferior, sigmoid or S-shaped, lump, disc, L-shaped, and superior CRFE [ 5 ]. The inferior form is the most common among the CFRE, and the superior form is the least common [ 5 ].…”

Cross fused renal ectopia with associated renal cell carcinoma

“…Current literature on cross-fused renal ectopia consists of case reports. 3 , 4 Its overall prevalence is estimated to be 1 in 900 live births. 5 This congenital renal abnormality in conjunction with a renal mass is even more uncommon.…”