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Combined renal and pyelic fusion with crossed ectopia of single ureter
COMBINED
RENAL AND PYELIC FUSION WITH
CROSSED ECTOPIA
OF SINGLE URETER
F’.ARAGONA,
M.D.
A, MARCONI,
M.D.
V. SERRETTA,
M.D.
C. SPINELLI,
M.D.
L. FIORENTINI,
M.D.
From the Urologic Service, Institute of General Surgery, University of Pisa, Italy
ABSTRACT-A case of a forty-five-year-old woman with fused kidneys and intercommunicating pelves drained by a single ureter crossing the midline is reported. A review of the literature is presented.
Fused kidneys with intercommunicating renal pelves drained by a single ureter crossing the midline is a rare malformation. To our knowledge, only 1 case has been reported in the world literature. l Case Report A previously healthy forty-five-year-old woman was admitted for evaluation of hypertension and intermittent, dull pain in the lower right abdomen. On admission (May, 1983), physical examination revealed only a moderate
scoliosis and no abdominal mass was palpable. Serum creatinine was 1.4 mg/lOO ml, urea clearance 72.20 (normal 76-131), and glomerular filtration rate was 44.7 mllmin (normal 103--144). Urine culture was positive. Chest roentgenogram and plain film of the abdomen revealed a complete situs inversus viscerum with dextrocardia. Intravenous pyelogram showed a malrotated right kidney with dilated calyces and an anteriorly directed pelvis that communicated across the midline with the grossly dilated pelvis of the left kidney (Fig.
FIGURE 1. (A) IVP shows malrotated right kidney and small left kidney with intercommunicating pelves drained by single ureter that extends from right renal pelvis across midline to left side of bladder. (B) Retrograde pyelogram shows single ureter passing from left ureteric orijice to right side of kidney, crossing spine in front of first sacral vertebra.
UROLOGY
/ OCTOBER
1986
/ VOLUME
XXVIII,
NUMBER
4
339
1
R
2. Renal scan shows two renal masses, smaller on left and larger on right, with some activity over midline. FIGURE
1A). Both kidneys seemed to be joined at the lower poles. The common pelvis was drained by a single ureter that extended from the right pelvis across the midline to the left side of the bladder. Retrograde cystography showed no ureteral reflux. At cystoscopy a left hemitrigone with a single normal-shaped meatus was found. Retrograde pyelography showed the single ureter passing from the left ureteral orifice to the right kidney, crossing the spinal column at the level of the first sacral vertebra (Fig. 1B). Renal scanning revealed two renal masses, a smaller left one and a larger right one, with some activity over the midline (Fig. 2). Percutaneous an-
terograde pyelography of the left kidney (Fig. 3A), and real-time renal ultrasonography clearly demonstrated the intercommunication between the pelves of the right and left renal masses (Fig. 3B). At operation a medially fused kidney at L3L4 level was noticed; the total renal mass was irregular, both renal pelves were anterior and intercommunicating, drained by a single ureter crossing the midline. The left kidney was small and severely dilated. Intercommunicating renal masses were severed, and a left nephrectomy was performed. Her postoperative course was uneventful. Five months later, the patient had sterile urine, but her hypertension has not subsided. Comment Until now, only 3 cases of renal fusion with intercommunicating pelves have been reported in the world literature. Each case exhibited a particular anatomic variety: (1) two fused kidneys with a single pelvis drained by two separated ureters,2 (2) two fused kidneys drained by a single Y-shaped ureteq3 (3) two kidneys on both sides of the midline fused at lower pole and jointed by a single pelvis drained by only one ureter which connects one side of the common pelvis to the opposite side of the bladder. This last variety was described by Cass and Vitko in 1972,’ who reported on a thirteenyear-old boy in whom a solitary ureter entered the bladder on the right side crossing the midline. We believe our case is the second such report in the literature. An embryologic explanation of this anomaly is difficult. The first variety might represent the FIGURE 3. Percutaneous anterograde pyelography of left kidney (A), and real-time renal ultrasonography (B) clearly demonstrate intercommunication between pelves of right and left renal masses.
340
UROLOGY
i OCTOBER1986
/ VOLUMEXXVIII.NUMBER4
consequence of a midline fusion of the ureteral buds as they grow to meet the two renal blastemas.4 We agree with Brueziere and Fretin that this hypothesis does not seem to be true since the excretory duct tends to divide rather than join during its cranial progression. In the second variety a solitary ureter bifurcated into 2 branches, each of them stimulating the corresponding renal mass. For the third variety, Cass and Vitko’ proposed that “a single ureter crossed to the opposite side and then divided into two halves, with half crossing the midline before each half influenced the development of its renal mass.” According to this hypothesis, the present malformation may represent a crossed ectopia of a supernumerary kidney with contralateral agenesis or a simple crossing of a ureteral branch to induce a normal kidney in situ.6 However, in our case no traces of ureteral division were seen or ureteral remnants found at operation, as in the case reported by Cass and Vitko. Furthermore it is unlikely that structures which already have advanced to such a stage that they are capable of inducing formal organ differentiation would be resorbed.7 Another possible explanation is that the existence of a ureteric bud is not essential for the development of renal blastema. In the past, the generally accepted theory of renal development was expressed succinctly by Potter,8 who stated, “a kidney never develops in the absence of a ureter.” Campbell9 also noted that ureteral agenesis always occurred in conjunction with aplasia or agenesis of the kidney. However Ashley and Mostofi7 reported on 11 cases in which there was development of the kidney without a ureter being present. This type of defect has been reported previously in a very few cases. Absence of one ureteric bud and the fusion of metanephric blastemas was reported in a lo-mm human embryo by Boyden. lo Brown” studied mice with genetic renal failure and noted that the metanephric blastema developed when the ureter failed to form. A g-mm human embryo without ureteric buds but with apparently normal wolffian ducts and metanephrogenic blastema present was described by Gruenwald.12 Nation13 recorded a series of 16 cases of dysgenesis of the kidney. In 1 of these cases there was complete absence of the renal pelvis and of the ureter, and in 2 others the upper ends of the ureters did not reach the kidneys.
UROLOGY
/
OCTOBER
1986
/ VOLUME
XXVIII,
NUMBER
Ashley and Mostofi7 suggested that the presence of the ureteric bud is not necessary for the kidney to develop, and that the metanephrogenie blastema has within itself the potentiality for differentiation into a kidney. In our opinion, the present anomaly might result from the association of 3 distinct malformations: (1) union of the two nephrogenic blastemas at an early stage (the anteriorly placed pelvis indicates that fusion probably occurred before rotation was completed); (2) crossing of the left ureter to the opposite side and induction of the right renal blastema to full development, according to Potter’s8 theory; (3) agenesis of the right ureteral bud, as proved by the missing hemitrigone. The left nephrogenic blastema might have developed, at least in part, without the ureter being present, with potentiality for renal differentiation in the structures of the nephrogenic ridge themselves. On the one hand it is likely the intercommunication between the pelves of the right and left masses provided a further stimulus for the left nephrogenic blastema to differentiate into renal substance, and on the other hand it assured the drainage necessary for function. Clinica Chirurgica Generale Spedali Riuniti S. Chiara Via Roma 57, 56100 Pisa, Italy (DR. ARAGONA) References 1. Cass AS, and Vitko RJ: Unusual variety of crossed renal ectopy with only one ureter, J Urol 107: 1056 (1972). 2. Kron SD, and Meranze DR: Completely fused pelvic kidney, ibid 62: 278 (1949). 3. Burstein HI: Double kidney with Y-shaped ureter and ureteral calculus in an infant, Urol Cutan Rev 42: 575 (1938). 4. Potampa PB, Hyman MD, and Catlow CE: An unusual renal anomalv: combined tandem and horseshoe kidnev., _ I Urol 61: 340 (1949)’ 5. Brueziere J, and Fretin J: A new case of pyelic fusion, Eur Urol 6: 249 (1980). 6. Gray SW, and Skandalakis JE: Embryology for surgeons. The embryological basis for the treatment of congenital defects, Philadelphia, WB. Saunders, 1972, p 443. 7. Ashley DJB, and Mostofi FK: Renal agenesis and dysgenesis, J Urol 83: 211 (1960). 8. Potter EL: Pathology of the Fetus and the Newborn, Chicago. Year Book Medical Publishers, 1952. “9. ‘Campbell M: Ureteral triplication, J Urol 70: 686 (1950). 10. Boyden EA: Description of a horseshoe kidney associated with left inferior vena cava and disc-shaped suprarenal glands, together with a note on the occurrence of horseshoe kidney in human embryos, Anat Ret 51: 187 (1931). 11. Brown AL: An analysis of the developing metanephros in mouse embryos with abnormal kidneys, Am J Anat 47: 117 (1931). 12. Gruenwald P: The mechanism of kidney development in human embryos as revealed by an early stage of agenesis of the ureteric buds, Anat Ret 75: 237 (1939). 13. Nation EF: Renal aplasia: study of 16 cases, J Urol51: 579 (1944).
4
341
RENAL AND PYELIC FUSION WITH
CROSSED ECTOPIA
OF SINGLE URETER
F’.ARAGONA,
M.D.
A, MARCONI,
M.D.
V. SERRETTA,
M.D.
C. SPINELLI,
M.D.
L. FIORENTINI,
M.D.
From the Urologic Service, Institute of General Surgery, University of Pisa, Italy
ABSTRACT-A case of a forty-five-year-old woman with fused kidneys and intercommunicating pelves drained by a single ureter crossing the midline is reported. A review of the literature is presented.
Fused kidneys with intercommunicating renal pelves drained by a single ureter crossing the midline is a rare malformation. To our knowledge, only 1 case has been reported in the world literature. l Case Report A previously healthy forty-five-year-old woman was admitted for evaluation of hypertension and intermittent, dull pain in the lower right abdomen. On admission (May, 1983), physical examination revealed only a moderate
scoliosis and no abdominal mass was palpable. Serum creatinine was 1.4 mg/lOO ml, urea clearance 72.20 (normal 76-131), and glomerular filtration rate was 44.7 mllmin (normal 103--144). Urine culture was positive. Chest roentgenogram and plain film of the abdomen revealed a complete situs inversus viscerum with dextrocardia. Intravenous pyelogram showed a malrotated right kidney with dilated calyces and an anteriorly directed pelvis that communicated across the midline with the grossly dilated pelvis of the left kidney (Fig.
FIGURE 1. (A) IVP shows malrotated right kidney and small left kidney with intercommunicating pelves drained by single ureter that extends from right renal pelvis across midline to left side of bladder. (B) Retrograde pyelogram shows single ureter passing from left ureteric orijice to right side of kidney, crossing spine in front of first sacral vertebra.
UROLOGY
/ OCTOBER
1986
/ VOLUME
XXVIII,
NUMBER
4
339
1
R
2. Renal scan shows two renal masses, smaller on left and larger on right, with some activity over midline. FIGURE
1A). Both kidneys seemed to be joined at the lower poles. The common pelvis was drained by a single ureter that extended from the right pelvis across the midline to the left side of the bladder. Retrograde cystography showed no ureteral reflux. At cystoscopy a left hemitrigone with a single normal-shaped meatus was found. Retrograde pyelography showed the single ureter passing from the left ureteral orifice to the right kidney, crossing the spinal column at the level of the first sacral vertebra (Fig. 1B). Renal scanning revealed two renal masses, a smaller left one and a larger right one, with some activity over the midline (Fig. 2). Percutaneous an-
terograde pyelography of the left kidney (Fig. 3A), and real-time renal ultrasonography clearly demonstrated the intercommunication between the pelves of the right and left renal masses (Fig. 3B). At operation a medially fused kidney at L3L4 level was noticed; the total renal mass was irregular, both renal pelves were anterior and intercommunicating, drained by a single ureter crossing the midline. The left kidney was small and severely dilated. Intercommunicating renal masses were severed, and a left nephrectomy was performed. Her postoperative course was uneventful. Five months later, the patient had sterile urine, but her hypertension has not subsided. Comment Until now, only 3 cases of renal fusion with intercommunicating pelves have been reported in the world literature. Each case exhibited a particular anatomic variety: (1) two fused kidneys with a single pelvis drained by two separated ureters,2 (2) two fused kidneys drained by a single Y-shaped ureteq3 (3) two kidneys on both sides of the midline fused at lower pole and jointed by a single pelvis drained by only one ureter which connects one side of the common pelvis to the opposite side of the bladder. This last variety was described by Cass and Vitko in 1972,’ who reported on a thirteenyear-old boy in whom a solitary ureter entered the bladder on the right side crossing the midline. We believe our case is the second such report in the literature. An embryologic explanation of this anomaly is difficult. The first variety might represent the FIGURE 3. Percutaneous anterograde pyelography of left kidney (A), and real-time renal ultrasonography (B) clearly demonstrate intercommunication between pelves of right and left renal masses.
340
UROLOGY
i OCTOBER1986
/ VOLUMEXXVIII.NUMBER4
consequence of a midline fusion of the ureteral buds as they grow to meet the two renal blastemas.4 We agree with Brueziere and Fretin that this hypothesis does not seem to be true since the excretory duct tends to divide rather than join during its cranial progression. In the second variety a solitary ureter bifurcated into 2 branches, each of them stimulating the corresponding renal mass. For the third variety, Cass and Vitko’ proposed that “a single ureter crossed to the opposite side and then divided into two halves, with half crossing the midline before each half influenced the development of its renal mass.” According to this hypothesis, the present malformation may represent a crossed ectopia of a supernumerary kidney with contralateral agenesis or a simple crossing of a ureteral branch to induce a normal kidney in situ.6 However, in our case no traces of ureteral division were seen or ureteral remnants found at operation, as in the case reported by Cass and Vitko. Furthermore it is unlikely that structures which already have advanced to such a stage that they are capable of inducing formal organ differentiation would be resorbed.7 Another possible explanation is that the existence of a ureteric bud is not essential for the development of renal blastema. In the past, the generally accepted theory of renal development was expressed succinctly by Potter,8 who stated, “a kidney never develops in the absence of a ureter.” Campbell9 also noted that ureteral agenesis always occurred in conjunction with aplasia or agenesis of the kidney. However Ashley and Mostofi7 reported on 11 cases in which there was development of the kidney without a ureter being present. This type of defect has been reported previously in a very few cases. Absence of one ureteric bud and the fusion of metanephric blastemas was reported in a lo-mm human embryo by Boyden. lo Brown” studied mice with genetic renal failure and noted that the metanephric blastema developed when the ureter failed to form. A g-mm human embryo without ureteric buds but with apparently normal wolffian ducts and metanephrogenic blastema present was described by Gruenwald.12 Nation13 recorded a series of 16 cases of dysgenesis of the kidney. In 1 of these cases there was complete absence of the renal pelvis and of the ureter, and in 2 others the upper ends of the ureters did not reach the kidneys.
UROLOGY
/
OCTOBER
1986
/ VOLUME
XXVIII,
NUMBER
Ashley and Mostofi7 suggested that the presence of the ureteric bud is not necessary for the kidney to develop, and that the metanephrogenie blastema has within itself the potentiality for differentiation into a kidney. In our opinion, the present anomaly might result from the association of 3 distinct malformations: (1) union of the two nephrogenic blastemas at an early stage (the anteriorly placed pelvis indicates that fusion probably occurred before rotation was completed); (2) crossing of the left ureter to the opposite side and induction of the right renal blastema to full development, according to Potter’s8 theory; (3) agenesis of the right ureteral bud, as proved by the missing hemitrigone. The left nephrogenic blastema might have developed, at least in part, without the ureter being present, with potentiality for renal differentiation in the structures of the nephrogenic ridge themselves. On the one hand it is likely the intercommunication between the pelves of the right and left masses provided a further stimulus for the left nephrogenic blastema to differentiate into renal substance, and on the other hand it assured the drainage necessary for function. Clinica Chirurgica Generale Spedali Riuniti S. Chiara Via Roma 57, 56100 Pisa, Italy (DR. ARAGONA) References 1. Cass AS, and Vitko RJ: Unusual variety of crossed renal ectopy with only one ureter, J Urol 107: 1056 (1972). 2. Kron SD, and Meranze DR: Completely fused pelvic kidney, ibid 62: 278 (1949). 3. Burstein HI: Double kidney with Y-shaped ureter and ureteral calculus in an infant, Urol Cutan Rev 42: 575 (1938). 4. Potampa PB, Hyman MD, and Catlow CE: An unusual renal anomalv: combined tandem and horseshoe kidnev., _ I Urol 61: 340 (1949)’ 5. Brueziere J, and Fretin J: A new case of pyelic fusion, Eur Urol 6: 249 (1980). 6. Gray SW, and Skandalakis JE: Embryology for surgeons. The embryological basis for the treatment of congenital defects, Philadelphia, WB. Saunders, 1972, p 443. 7. Ashley DJB, and Mostofi FK: Renal agenesis and dysgenesis, J Urol 83: 211 (1960). 8. Potter EL: Pathology of the Fetus and the Newborn, Chicago. Year Book Medical Publishers, 1952. “9. ‘Campbell M: Ureteral triplication, J Urol 70: 686 (1950). 10. Boyden EA: Description of a horseshoe kidney associated with left inferior vena cava and disc-shaped suprarenal glands, together with a note on the occurrence of horseshoe kidney in human embryos, Anat Ret 51: 187 (1931). 11. Brown AL: An analysis of the developing metanephros in mouse embryos with abnormal kidneys, Am J Anat 47: 117 (1931). 12. Gruenwald P: The mechanism of kidney development in human embryos as revealed by an early stage of agenesis of the ureteric buds, Anat Ret 75: 237 (1939). 13. Nation EF: Renal aplasia: study of 16 cases, J Urol51: 579 (1944).
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