Original Article
CROSSED FUSED RENAL ECTOPIA M ULTIDETECTOR COM PUTED
TOM OGRAPHY STUDY
Sharma V
1, Ramesh Babu C.S *
2, Gupta O.P
3.
ABSTRACT
Address for Correspondence: C.S.Ramesh Babu, Associate Professor of Anat omy, M uzaffarnagar
M ed ical Co llege, N.H.58, Opp . Beghraj pu r Ind ust r ial Area, M u zaf f ar n agar (UP) Ind ia. M obile: +91-9897249202. E-M ail: csrameshb@gmail.com
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1 Assistant Professor of Anat omy, M uzaffarnagar M edical College, M uzaffarnagar. India. * 2 Associate Professor of Anat omy, M uzaffarnagar M edical College, M uzaffarnagar, India. 3 Dr.O.P.Gupta Imaging Center, Sumer Bhawan, Bachcha Park, M eerut , India.
Crossed renal ect opia is one of the rarest congenital m alformations w here a kidney is located on the side opposite to t he side of its uret eral insertion into the urinary bladder and is generally fused with the normally located ipsilateral mate. Generally this anom aly remains as a silent clinical entity and is incidentally detected during evaluation for other conditions. We report here three such cases of crossed fused renal ect opia de-tected by multidetector row cont rast enhanced computed t omography. Crossed fused renal ectopia of inferior type was observed in a male on the right side with the uret er of the ectopic left kidney crossing the midline. In two female patients, L-shaped or tandem kidney was noted, one on the right and anot her on the left side. Over all in t wo cases the left kidney was ect opic and in one the right kidney. No renal pathologies like urinary tract infection, nephrolithiasis or hematuria w ere found in our patients.
KEYW ORDS: Crossed fused renal ect opia, Tandem kidney, L-shaped kidney, Renal ectopia, M ult idetector com puted tom ography, Renal fusion anomaly.
INTRODUCTION
Int J Anat Res 2014, Vol 2(2):305-09. ISSN 2321- 4287
Received: 22 M arch 2014
Peer Review: 22 M arch 2014 Published (O):30 April 2014 Accepted: 10 April 2014 Published (P):30 June 2014 Internat ional Journal of Anat omy and Research
ISSN 2321-4287 www.ijmhr.org/ ijar.ht m
Congenital malformat ions of t he urinary system are not uncommon and crossed renal ect opia (CRE) is one of t he rare posit ional and fusion anomalies of t he kidney. Crossed renal ect opia occurs w hen a kidney is locat ed on t he side opposite from which it s ureter enter int o t he urinary bladder [1]. In about 90 % of cases, t he crossed ect opic kidney fuses wit h it s ipsilateral mate. Crossed fused renal ect opia is t he second most common renal fusion anomaly aft er t he horse-shoe kidney wit h an est imated incidence of 1: 2000 t o 1: 7500 aut o psies.[ 1,2] . The prevalence of t he crossed renal ect opia w it h fusion was est imated t o be 1 in 1000 live birt hs [3]. In a review of 400 children evaluat ed by DM SA renal scan, crossed fused renal ect opia
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genit ourinary and gast roint est inal syst em s [6,7,8,9] . In t his case series, w e review t he radiological feat ures of crossed f used renal ect o p ia d et ect ed by m ult idet ect o r ro w computed t omographic (M DCT) examinat ion in t hree pat ient s. It is recent ly suggest ed t hat M DCT urography is t he m odalit y of choice comprehensively evaluat ing anatomical features o f t h is ren al f u sio n an o m aly in a single examinat ion [2].
M ATERIALS AND M ETHODS
Three cases of crossed f used renal ect opia present ed here w ere evaluat ed in a single d iagno st ic cen t er d u r in g t h e p er io d f ro m Oct o b er, 2012 t o Feb r u ar y, 2014 an d t h e anomaly was detect ed incident ally w hen t he pat ient s were exam ined for ot her suspected condit ions. The diagnost ic cent er rout inely obt ains w rit t en inform ed consent f rom t he pat ient s before cont rast inject ion. All pat ient s u nd er w en t co n t rast en han ced com p u t ed t omography (CECT) by a 64 channel scanner (GE Optima-60) and received 85 – 100 ml of non-ionic cont rast (Omnipaque, 300 mg I/ ml) at t he rate of 5 ml/ s int ravenously. Scans w ere obtained from diaphragm t o upper part of t high and delayed phase scans were also obtained. The scans were analyzed in a separate work stat ion (AW vo lu m e sh are 4.5) w it h m u lt ip lan ar reformatting and maximum intensit y projection (M IP) an d vo lum e ren d ered (VR) im ages obtained.
result ing in a L-shaped crossed f used renal ect opia (Fig.2). The right uret er crosses t he midline at L-5 vertebra. Hilum of t he right kidney is directed anteriorly whereas t hat of left kidney an t ero lat erally. Sligh t d i lat at io n o f lef t pelvicalyceal system is seen. The ect opic right kid ney receives it s art er ial sup p ly f ro m a recurrent branch having a curved course arising from t he left common iliac artery and crossing anterior t o aort ic bifurcat ion. A short right renal vein and a longer left renal vein drain int o left common iliac vein.
Fig.1:58 year old m ale with crossed fused renal ectopia of the left kidney. 1-A:VR urographic image showing the fusion of upper pole of crossed ect opic left kidney (LK) wit h the lower pole of normally posit ioned right kidney (RK)- inferior ectopia type. The left ureter is crossing the midline and open into urinary bladder on t he left side. 1-B: VR image showing the presence of two right renal art eries from t he aorta ent ering t he medially facing hilum of right kidney (1-C- coronal image). A single left renal artery (arrow in 1-B and 1-D) arising from anterior aspect of aorta just proxim al t o its bifurcation passes to the right and has a precaval course (passing anterior to inferior vena cava (IVC) t o reach t he hilum (1-D). Hilum of the left kidney faces ant eriorly.
OBSERVATIONS
Case-1: 58 year old man wit h empt y left renal
fossa and presence of t wo renal masses on t he right side. Upper pole of t he ect opic left kidney has fused wit h t he lower pole of t he ort hot opic right kidney- crossed fused renal ect opia inferior t ype.(Fig.1) Left ureter crosses t he midline and insert s int o t he urinary bladder on t he left side. Hilum of t he ect opic left kidney is direct ed anteriorly. The ect opic left kidney is supplied by an artery arising from aorta just above t he level of it s bif u rcat ion and pass ant erior t o IVC (Precaval course) t o reach t he hilum.
Case-2: 28 year old w oman w it h empt y right
ren al f o ssa. Th e r ight kid n ey is p laced t ransversely anterior t o L-4 vertebra and fuses wit h t he lower pole of t he ort hot opic left kidney
Case-3: 70 year old w om an w it h L-shaped
Fig.2: 28 year old fem ale having crossed fused renal ect opia w it h L-shaped o r Tandem kidney. 2-A:VR urographic image show ectopic right kidney, placed hori-zontally in front of L-4 vertebra, is fusing w ith t he lower pole of the left kidney. The right ureter emerging from the anteriorly placed hilum is crossing t he midline in front of L-5 vert ebra and opens into urinary bladder on the right side. M ildly dilated left pelvicalyceal syst em, suggestive of hydronephrosis, is emerging from t he ant erolaterally directed hilum. 2-B: VR image show s a single left renal artery arise from aorta opposite to infe-rior mesenteric artery. 2-C:Coronal image. The right re-nal artery supplying t he ectopic right kidney arises from the left comm on iliac artery and has a recurrent course to reach right kidney Arrow- left renal vein. 2-D: coronal image showing right renal vein (short arrow) and left renal vein (long arrow); both drain into left common iliac vein.
Fig.3: 70 years old female having crossed fused renal ect opia w it h L-shaped or Tandem kidney. 3-A: VR urographic im age show ectopic left kidney (LK) placed horizontally anterior to L4 and L5 vertebrae is fusing with the low er pole of the norm ally placed right kidney (RK). The left uret er emerges from the anteriorly placed hi-lum and crosses t he m idline at sacral promontory to insert into urinary bladder in the left side. The hilum of the right kidney also faces anteriorly. 3-B: VR image show a single right renal artery, arising opposite to t he level of superior m esent eric artery, supply the right kidney. The ectopic left kidney is supplied by 4 arteries (arrows); two of them arise from the ant erior aspect of aorta just above it s bifurcat ion. The t hird artery arises from the medial aspect of left common iliac and crosses the right com mon iliac artery to reach the left kidney. A fourth art ery w hich is very short arise from the right com mon iliac artery to supply the left kidney. 3-C: Coronal im-age; 3-D: Axial image.
DISCUSSION
Fig.4: Six types of crossed fused renal ectopia. A- Unilat-eral fused kidney- inferior ectopia t ype; B- Sigmoid or S-shaped kidney; C- Lump kidney; D- L-shaped kidney; E- Disc kidney; F- Unilateral fused kidney- superior ec-topia type.
Crossed renal ect opia (CRE) is a rare t ype of renal fusion anomaly in which bot h t he kidneys are sit uated on one side and in about 90 % of such cases t he crossed ect opic kidney is fused
wit h t he ort hot opically located kidney. In t his condition t he ect opic kidney is located contralat-eral t o t he side of it s ureteric orifice and t he ureter of t he ect opic kidney cross t he midline which dist inguishes t his condit ion from horse-shoe kidney. M cDonald and M cClellan [10] clas-sified t he crossed renal ect opia int o (i) crossed ect opia w it h fusion (90% cases); (ii) Crossed ect opia w it hout fusion’ (iii) unilat eral crossed ect op ia (asso ciat ed w it h u ni lat eral renal agenesis) and (iv) bilat eral crossed ect opia wit hout fusion(bot h ureters cross t he midline). In CRE, t he left t o right ect opia is more common (t he left kidney crossing t o t he right side) and males are more commonly affected.
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CONCLUSION
kidney in which t he crossed kidney lies inferiorly wit h t he renal pelvis directed laterally and t he normally posit ioned kidney lies superiorly wit h t he pelvis directed medially. (C) Unilateral Lump kidney wit h fusion occurring over a wide margin and both renal pelvis directed anteriorly; located more inferiorly. (D)L-Shaped or Tandem kidney in which t he crossed kidney lies inferiorly and t ransversely fusing wit h t he lower pole of t he normal kidney. (E) Unilateral disc kidney in which t he fusion occurs along t he medial borders and (F) Unilateral fused kidney superior ectopia t ype is t he least common t ype; t he ect opic kidney is placed superiorly wit h it s lower pole fusing wit h t he upper pole of t he normal kidney. Bot h renal pelvis are anterior.
The precise mechanism of occurrence of crossed renal ect opia is not fully underst ood and several t heories have been put forward t o explain t his anom aly. Am ong t hem are t he m echanical t heory (abnorm ally placed um bilical arteries mechanically obst ruct ing cephalad migrat ion), t he ureteral t heory (wandering of t he ureteral bud t o the opposite side), the teratogenic theory, t he genet ic t heory (observat ion of t he anomaly in families) and t heory of abnormal rotat ion of the caudal end of t he fetus (increased prevalence of t his anomaly wit h scoliosis).
CRE is sporadically report ed in t he literat ure because t his anomaly m ay remain as a silent clinical ent it y wit hout producing any signs and sympt oms and t his is supported by several case report s in cadavers. [11–14]. In t hese four case report s, male t o female rat io and left t o right rat io is 3:1. Case st udies of pat ient s invest igated for nephrolit hiasis and pyelonephrit is w it h inferior t ype of crossed fused renal ect opia of t he left kidney, have been report ed [15-17]. Inferior ectopia t ype of CRE is t he most common t ype. Only in one case inferior t ype of crossed fused renal ect opia of t he right kidney w as detected [18]. Sigmoid t ype of kidney, which is seco nd com m o n t yp e of CRE w it h f usio n, associated wit h staghorn calculus was reported by Amin et al. [19]. Superior ect opia, t he rarest t ype of CRE wit h fusion, was reported in a female pat ient by Patel and Singh [20]. In our st udy L-shaped kidneys w ere found in t w o fem ale pat ient s and inferior t ype of CRE in one male pat ient .
A number of case series of CRE wit h fusion have been published. [ 21-24] . Analysis of t hese st udies indicate t hat t he CRE wit h fusion occurs more commonly in males and t he left kidney is affect ed m ore t han t he right kidney. M any congenital anomalies are associated wit h CRE w it h f u sion such as vagin al agen esis [ 6] , VACTERL associat ion [8], TAR syndrome [9], renal dyaplasia [25] and a single ureter [26]. Kulkarni etal detected intest inal malrotat ion associated w it h a lum p kidney in a m ale cadaver. [ 7] . Crossed fused left renal ect opia wit h left sided polydact yly was found in a 24 week aborted male fet us [ 27] . We did not f ind any congenit al anomaly in our cases.
Crossed fused renal ect opia is an uncomm on congenital anomaly which can remain asymp-t omaasymp-t ic asymp-t hroughouasymp-t life and hence undeasymp-tecasymp-ted. It is generally found incidentally when pat ient s are invest igat ed for ot her abdominal pat holo-gies. In some cases it may be associated wit h nephrolit hiasis, recurrent infect ions , hydroneph-rosis and congenital malformat ions affect ing skeletal, gast rointestinal and urogenital systems. We have reported t wo cases of a rare t ype of L-shaped or t andem kidneys, bot h found in females, t hough CRE is more common in males. M ult idetect or computed t omographic (M DCT) evaluat ion provides excellent anat omical details o f t h is an om aly in a single exam in at io n im port ant for surgeons, nephrologist s and radiologist s for proper management .
Acknow ledgement
Conflicts of Interests: None
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Technical assistance provided byM r. Arjun Singh in preparation of CT images, M r.Sushil Kumar and M r.Tit hender in preparat ion of phot ographs and M r.Ch and ra Prakash , Ar t ist is sin cerely acknowledged.
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Sharma V, Ramesh Babu C.S, Gupta O.P. CROSSED FUSED RENAL ECTOPIA M ULTIDETECTOR COM PUTED TOM OGRAPHY STUDY. Int J Anat Res 2014;2(2):305-09.
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