KIDNEY
Multicystic Renal Dysplasia Pathologic Thomas G.
)V!
and Clinical Observations in 22 Cases
Gipson, M.D.,*
E. Everett Anderson, M.D.,** William D. Bradford,
ULTICYSTIC RENAL DYSPLASIA is
clinical-pathological entity of considerable importance. It represents both the most frequent abdominal mass palpable in newa
-
born
infants,’ and is also the
most
common
cystic lesion of the neonatal kidneys. 2,3 [Renal dysplasia should not be confused with hypoplasia which is simply a reduction in size of an otherwise normal kidney.] On genetic, clinical, radiographic, and pathologic grounds,~3 renal dysplasia is separable from infantile polycystic renal disease.’ This report describes the distinguishing features of multicystic renal dysplasia and emphasizes its usually favorable outcome when not associated with other major congenital anomalies. Source of the Cases
The clinical and pathologic files of Duke University Medical Center were searched for pediatric patients with the diagnosis of renal dysplasia, multicystic kidney, or polycystic kidney treated between January 1, 1948 and April 1, 1973. Then, those cases whose pathologic material was available for review Department of Pathology and Department of Surgery, Division of Urology, Duke University Medical Center, Durham, N.C. * Resident in Pathology. ** Professor of Urology. &dag er; Associate Professor of Pathology. Correspondence to William D. Bradford, M.D., P. O. Box 3005, Duke University Medical Center, Durham, N.C. 27710.
896
M.D.†
included in this study. Roentgenothese children were studied by intravenous and retrograde urography, and cystoscopy. Ultrasound techniques were not used routinely at the time. But roentgenographic studies or clinical course, although strongly suggestive of renal dysplasia, were of themselves not deemed sufficient for an were
graphically,
unequivocal diagnosis. Twenty-two patients
were identified by tissue and other studies as having multicystic renal dysplasia, including 1 I boys and 11 girls. Their ages ranged from 27 weeks gestation to five years. In 13, the left kidney was the site of the dysplastic process; in nine, the right kidney. In every one, the lesion was unilateral.
Clinical
Signs
and
Symptoms
Fourteen of the 22 patients came to the attention of a physician during the first week after birth. In seven of these 14 patients, the parents had noted an abdominal mass. In four others, an abdominal mass was palpable upon examination at the hospital. Of the eight children over one week of age, four were brought to the physician because of an abdominal mass. In two others, an abdom-inal mass was identified on physical examination. Thus 17 of the 22 patients had a palpable mass at the time of admission to the hospital. The mass was frequently movable and usually nontender. Seven ptients had been referred primarily _
A
Flc. 1. Gross appearance of unilateral multicystic renal dysplasia,. Note the multicystic enlargement of this nonreniform kidney and the short segment of atretic
ureter
(arrow).
for evaluation of a recognizable congenital malformation, or because of severe symptoms resulting from congenital heart disease or gastrointestinal atresia. Conceivably such problems detracted from early identification of a renal mass.
fibrous tissue
stroma.
Almost
always,
the
is atretic or markedly corresponding stenotic. Twenty cases in this series had such an abnormality. In the other two cases, gross ureter
photographs of the kidney are not available, pathologist’s records state that the
but the
ureters were
&dquo;unremarkable.&dquo;
Pathology Microscopic Appearance Gross
The
Appearance is
multicystic dysplastic kidney larged, cystic, and nonreniform (Fig. 1). At surgery, it is easily identified because it is unilateral, large, and often resembles a collecen-
tion of grapes. The cysts range from less than one millimeter up to several centimeters in diameter. When uninfected, the cysts are filled with clear yellow fluid resembling the ultrafiltrate of plasma. When incised, the normal renal parenchyma is seen to be replaced by numerous cysts lying within a
Innumerable thick-walled cysts are seen throughout the kidney. Normal parenchyma is conspicuously absent, although small nests of normal-appearing nephronic elements are occasionally found. The loose connective tissue which surrounds the cysts may range from thin strands to extensive areas of fibrosis. This increase in connective tissue has been used in the past to differentiate renal dysplasia from other renal cystic lesions. Within the rather abundant stroma may be seen large nerve trunks, many blood vessels, and foci of
897
FIG. 2. Microscopic appearance of a primitive renal duct lined by columnar epithelium, and invested in a mantle of fibromuscutar connective tissue. X 100.
extramedullary erythropoiesis. Primitive ducts (Fig. 2) and nests of metaplastic cartilage (Fig. 3) are regarded as the principal microscopic criteria for diagnosis of renal dysplasia. Pathogenesis Renal
dysplasia is a spectrum with numermorphologic variants. The dysplasia may be unilateral or bilateral, segmental, cortical, medullary, or total. There may be no significant cyst formation and the involved kidney may be quite small. In this manuscript, we are discussing the cystic form of unilateral renal dysplasia. For the purpose of this study, renal dysplasia is defined as persistence of immature structures inappropriate for the gestational age of the patient.2,3 While authors differ considerably in what they consider &dquo;dysplastic&dquo; structure, the list frequently includes:’-’ 1) dilated ducts lined by columnar epithelium .and surrounded by fibromuscular mantle; 2) ous
898
FIG. 3. Microscopic appearance of a cartilage lying within the connective muhicystic tiys~3lastic kidney. x2a~.
foci of
nest
of metaplastic
tissue
stroma
of
a
small primitive ductules; abundant undifferentiated mesenchymal stroma; and 5) cysts of various origins. Clinical and experimental evidence have demonstrated that all the components except primitive ducts and metaplastic cartilage may be induced in the neonatal kidney and should be looked upon as acquired lesions-for example, primitive tubules and glomeruli are recognizable following ischemic renal necrosis in the newborn.8 Other primitive structures may be induced by obstruction, or by chronic inflammation.~7 Cysts are not necessarily congenital, for they may be induced chemically by such substances as diphenylamine.1o Thus, only primitive ducts and foci of cartilage seem to be truly pathognomic of renal dysplasia, as . Bernstein has emphasized.7 Accordingly, in this study, only these two structures have been deemed sufficient diagnostic evidence for patients to be included in our series. The literature concerning cystic changes in
4)
an
cartilage; 3)
the
kidney is most confusing because the pathogenesis of most forms of cystic disease has not been thoroughly established. Hildebrand in 1894 first theorized that cystic kidneys resulted from nonunion of the secretory and the collecting segments.&dquo; &dquo;Failure of union,&dquo; while not tenable to describe true polycystic disorders, may be of importance in the pathogenesis of renal dysplasia. Differentiation of the metanephrc~7_ genic tissue is under the influence of the ureteric bud. Inhibition of function of the ampulla of the ureteric bud early in fetal life will lead to diminished induction of nephrons and faulty maturation of those few nephrons which are induced. Microdissection studies have contributed to our understanding of cystic dysplasia and show a decrease in the total number of generations of tubules derived from the ureteral bud. These tubules are cystically dilated. 12 The role of ureteral atresia in pathogenesis is debated. One suggestion is that urinary tract obstruction causes dyplasia, since the patterns of dysplasia are related to the nature of the obstructive malformation.l~ An alternative view is that the ureteral abnormality is an integral part of the dysplastic process, rather than its cause, since when ampullary injury occurs early in the course of development, the ureter seems to be affected as well as the more distal areas. 14 Differential
Diagnosis
multicystic dysplastic kidney most frequently presents early in life as an asymptomatic abdominal mass. Occasionally the renal mass may be so large as to impede delivery. A
TABLE 1.
Findings by Intravenous in
the
Upon palpating an abdominal mass in the newborn period, the physician must also consider hydronephrosis, neuroblastoma, Wilms’ tumor, and true polycystic kidney of the infantile type. Multicystic renal dysplasia rarely occurs bilaterally; when it does, stillbirth is inevitable since the kidneys contain no functioning glomeruli. The earlier an abdominal mass is detected after birth, the more likely is the diagnosis to be multicystic renal dysplasia. Intravenous urography (Table 1) is most helpful in the diagnosis of abdominal masses in children. With multicystic renal dysplasia, the renal size is enlarged on the plain film of the abdomen. Usually, nonvisualization of contrast material in the collecting system occurs because of few or no functioning
glomeruli although rarely a multicystic kidney excrete contrast material, thereby confusing the differentiation between a multicystic kidney and a hydronephrotic kidney. will
At cystoscopy, the ureteral orifice on the affected side may be absent. When the ureteral orifice is present, retrograde ureterogram will demonstrate a ureter terminating blindly below the ureteropelvic junction. In
the renal size is enlarged, or nonvisualization of contrast material depending on the degree of cortical atrophy. Should there be sufficient renal cortex to excrete the contrast material, marked pyelocalyceal dilatation will be evident. In neuroblastoma, stippled calcification is found in 50 per cent of the masses, along with excellent visualization of contrast material in normal pyelocalyceal systems. When the
hydronephrosis,
with either decreased
Differential Diagnosis of Abdominal Masses in
Claildrera
Key: + = Present. 0 = Absent. I = Decreased.
899
arises from near the adrenal, the kidney is displaced inferiorly with lateral displacement of the superior pole. When the tumor arises from the sympathetic chain, the kidney and ureter are displaced laterally. With %Vilms’ tumor, there is usually prompt appearance of contrast material in an enlarged kidney with marked attenuation and distortion of the pyelocalyceal system. Rarely does invasion and obstruction of the renal vein occur; when it does, the intravenous urogram will demonstrate a nonfunctioning tumor
kidney. In polycystic renal disease of infancy, there are bilateral enlarged kidneys with decreased visualization of contrast material. When visualized, the excretion pattern may be in a sun ray or streaked pattern in the dilated collecting ducts, and the calyces are often not Newborns with infantile polycystic seen. disease (Type 1 of Potter) invariably die in the neonatal period of renal insufficiency and have cystic alterations of the liver as well.
by others.14 Three patients also had atresia. biliary In four patients, the contralateral kidney was found to be hydronephrotic. Three of these four children also had severe congenital anomalies, and died soon after their initial evaluation. Stenosis of the ureteropelvic junction was the cause of hydronephrosis in two of these children. The prognosis of contralateral hydronephrosis~erse is not necessarily serious unless it is massive and/or accompanied by other severe malformations.15 served
References 1.
masses
1958. 2. Kissane,
and Smith, M. G.: Dysplasia in and of Infancy and Childhood. St. Louis, C. V. Mosby Company, 1967,
J. H., of
Infancy
p.526. 3.
malformations. In Pathology of R. H. Heptinstall Ed., Boston. Little, Brown, and Company, 1966, p. 75. Ericsson, N. O., and Ivemark, B. I.: Renal dysplasia and pyelonephritis in infants and children. Arch. Pathol. 66: 255, 264, 1958. Gleason, D. C., McAlister, W. H., and Kissane, J. H.: Cystic disease of the kidneys in children. Am. J. Roentgenol. 100: 135, 1967. Pasternack, A.: Microscopic structural changes in macroscopically normal and pyeionephrotic kidneys of children. Ann. Paediatr. Fenn. Suppl. 14, 1960. Bernstein, J.: Developmental anomalies of the renal parenchyma: renal hypaplasia and dysplasia. In Pathology Annual, Sommers, S. C., Ed. New York, Appleton-Century-Crofts, Inc., 1968, p. 213. —, and Meyer, R.: Congenital abnormalities of the urinary system. II. Renal cortical and medullary necrosis. J. Pediatr. 59: 657, 1961. R.: Experimental study of renal and
—:
the
4.
5.
900
L. A., and Martin, L. W.: Abdominal in the newborn infant. Pediatrics 21: 596,
Pathology
Treatment, Outcome, and Prognosis
Nephrectomy is the treatment of choice for unilateral renal dysplasia. Dysplasia is not a progressive disease that will eventually affect the other side. Surgical exploration will also rule out the rare possibility of a poorly functioning Wilms’ tumor from renal vein occlusion. Our patients demonstrate the favorable prognosis of this condition when it occurs as an isolated malformation. Ten of the 12 patients without coexisting anomalies have done well since their nephrectomies. The remaining two patients had been admitted with serious attendant disease: one with fever and sepsis and the other, an immature infant of 27 weeks gestation, with severe apnea and respiratory distress. Both succumbed shortly after being hospitalized. Accompanying congenital anomalies are ominous prognostic signs. Nine of ten infants with multiple congenital anomalies died by the age of three months. In our series, congenital heart lesions and gastro-intestinal atresias were common (four each). This has been ob-
Longino,
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Congenital
Kidney,
—,
Meyer,
parenchymal maldevelopment (renal dysplasia). Washington, D.C., 3rd International Congress of Nephrology, September 1966. Safouh, M., Crocker, J. F. S., and Vernier, R. L.: Experimental cystic disease of the kidney. Lab. Invest. 23, 392, 1970. Hildebrand, O.: Weiterer Beitrag zur Pathalogischen Anatomic Der Nierengeschwulste. III. Congenitale Cystenniere nut Sarkombildung Arch. F. Klin. Chir. 48: 343, 1894. Osathanondh, V., and Potter, E. L.: Pathogenesis of polycystic kidneys. Type 2 due to inhibition of ampullary activity. Arch. Pathol. 77: 549, 1946. Potter, E. L.: Normal and Abnormal Development of the Kidney. Chicago, Year Book Medical Publishers, Inc., 1972, p. 154. Arey, J. B.: Cystic lesions of the kidney in infants and children. J. Pediatr. 54: 429, 1959. Pathak, I. G., and Williams, D. I.: Multicvstic and cytstic dysplastic kidneys. Br.J. Urol. 36:318, 1963.
Multicystic Renal Dysplasia Pathologic Thomas G.
)V!
and Clinical Observations in 22 Cases
Gipson, M.D.,*
E. Everett Anderson, M.D.,** William D. Bradford,
ULTICYSTIC RENAL DYSPLASIA is
clinical-pathological entity of considerable importance. It represents both the most frequent abdominal mass palpable in newa
-
born
infants,’ and is also the
most
common
cystic lesion of the neonatal kidneys. 2,3 [Renal dysplasia should not be confused with hypoplasia which is simply a reduction in size of an otherwise normal kidney.] On genetic, clinical, radiographic, and pathologic grounds,~3 renal dysplasia is separable from infantile polycystic renal disease.’ This report describes the distinguishing features of multicystic renal dysplasia and emphasizes its usually favorable outcome when not associated with other major congenital anomalies. Source of the Cases
The clinical and pathologic files of Duke University Medical Center were searched for pediatric patients with the diagnosis of renal dysplasia, multicystic kidney, or polycystic kidney treated between January 1, 1948 and April 1, 1973. Then, those cases whose pathologic material was available for review Department of Pathology and Department of Surgery, Division of Urology, Duke University Medical Center, Durham, N.C. * Resident in Pathology. ** Professor of Urology. &dag er; Associate Professor of Pathology. Correspondence to William D. Bradford, M.D., P. O. Box 3005, Duke University Medical Center, Durham, N.C. 27710.
896
M.D.†
included in this study. Roentgenothese children were studied by intravenous and retrograde urography, and cystoscopy. Ultrasound techniques were not used routinely at the time. But roentgenographic studies or clinical course, although strongly suggestive of renal dysplasia, were of themselves not deemed sufficient for an were
graphically,
unequivocal diagnosis. Twenty-two patients
were identified by tissue and other studies as having multicystic renal dysplasia, including 1 I boys and 11 girls. Their ages ranged from 27 weeks gestation to five years. In 13, the left kidney was the site of the dysplastic process; in nine, the right kidney. In every one, the lesion was unilateral.
Clinical
Signs
and
Symptoms
Fourteen of the 22 patients came to the attention of a physician during the first week after birth. In seven of these 14 patients, the parents had noted an abdominal mass. In four others, an abdominal mass was palpable upon examination at the hospital. Of the eight children over one week of age, four were brought to the physician because of an abdominal mass. In two others, an abdom-inal mass was identified on physical examination. Thus 17 of the 22 patients had a palpable mass at the time of admission to the hospital. The mass was frequently movable and usually nontender. Seven ptients had been referred primarily _
A
Flc. 1. Gross appearance of unilateral multicystic renal dysplasia,. Note the multicystic enlargement of this nonreniform kidney and the short segment of atretic
ureter
(arrow).
for evaluation of a recognizable congenital malformation, or because of severe symptoms resulting from congenital heart disease or gastrointestinal atresia. Conceivably such problems detracted from early identification of a renal mass.
fibrous tissue
stroma.
Almost
always,
the
is atretic or markedly corresponding stenotic. Twenty cases in this series had such an abnormality. In the other two cases, gross ureter
photographs of the kidney are not available, pathologist’s records state that the
but the
ureters were
&dquo;unremarkable.&dquo;
Pathology Microscopic Appearance Gross
The
Appearance is
multicystic dysplastic kidney larged, cystic, and nonreniform (Fig. 1). At surgery, it is easily identified because it is unilateral, large, and often resembles a collecen-
tion of grapes. The cysts range from less than one millimeter up to several centimeters in diameter. When uninfected, the cysts are filled with clear yellow fluid resembling the ultrafiltrate of plasma. When incised, the normal renal parenchyma is seen to be replaced by numerous cysts lying within a
Innumerable thick-walled cysts are seen throughout the kidney. Normal parenchyma is conspicuously absent, although small nests of normal-appearing nephronic elements are occasionally found. The loose connective tissue which surrounds the cysts may range from thin strands to extensive areas of fibrosis. This increase in connective tissue has been used in the past to differentiate renal dysplasia from other renal cystic lesions. Within the rather abundant stroma may be seen large nerve trunks, many blood vessels, and foci of
897
FIG. 2. Microscopic appearance of a primitive renal duct lined by columnar epithelium, and invested in a mantle of fibromuscutar connective tissue. X 100.
extramedullary erythropoiesis. Primitive ducts (Fig. 2) and nests of metaplastic cartilage (Fig. 3) are regarded as the principal microscopic criteria for diagnosis of renal dysplasia. Pathogenesis Renal
dysplasia is a spectrum with numermorphologic variants. The dysplasia may be unilateral or bilateral, segmental, cortical, medullary, or total. There may be no significant cyst formation and the involved kidney may be quite small. In this manuscript, we are discussing the cystic form of unilateral renal dysplasia. For the purpose of this study, renal dysplasia is defined as persistence of immature structures inappropriate for the gestational age of the patient.2,3 While authors differ considerably in what they consider &dquo;dysplastic&dquo; structure, the list frequently includes:’-’ 1) dilated ducts lined by columnar epithelium .and surrounded by fibromuscular mantle; 2) ous
898
FIG. 3. Microscopic appearance of a cartilage lying within the connective muhicystic tiys~3lastic kidney. x2a~.
foci of
nest
of metaplastic
tissue
stroma
of
a
small primitive ductules; abundant undifferentiated mesenchymal stroma; and 5) cysts of various origins. Clinical and experimental evidence have demonstrated that all the components except primitive ducts and metaplastic cartilage may be induced in the neonatal kidney and should be looked upon as acquired lesions-for example, primitive tubules and glomeruli are recognizable following ischemic renal necrosis in the newborn.8 Other primitive structures may be induced by obstruction, or by chronic inflammation.~7 Cysts are not necessarily congenital, for they may be induced chemically by such substances as diphenylamine.1o Thus, only primitive ducts and foci of cartilage seem to be truly pathognomic of renal dysplasia, as . Bernstein has emphasized.7 Accordingly, in this study, only these two structures have been deemed sufficient diagnostic evidence for patients to be included in our series. The literature concerning cystic changes in
4)
an
cartilage; 3)
the
kidney is most confusing because the pathogenesis of most forms of cystic disease has not been thoroughly established. Hildebrand in 1894 first theorized that cystic kidneys resulted from nonunion of the secretory and the collecting segments.&dquo; &dquo;Failure of union,&dquo; while not tenable to describe true polycystic disorders, may be of importance in the pathogenesis of renal dysplasia. Differentiation of the metanephrc~7_ genic tissue is under the influence of the ureteric bud. Inhibition of function of the ampulla of the ureteric bud early in fetal life will lead to diminished induction of nephrons and faulty maturation of those few nephrons which are induced. Microdissection studies have contributed to our understanding of cystic dysplasia and show a decrease in the total number of generations of tubules derived from the ureteral bud. These tubules are cystically dilated. 12 The role of ureteral atresia in pathogenesis is debated. One suggestion is that urinary tract obstruction causes dyplasia, since the patterns of dysplasia are related to the nature of the obstructive malformation.l~ An alternative view is that the ureteral abnormality is an integral part of the dysplastic process, rather than its cause, since when ampullary injury occurs early in the course of development, the ureter seems to be affected as well as the more distal areas. 14 Differential
Diagnosis
multicystic dysplastic kidney most frequently presents early in life as an asymptomatic abdominal mass. Occasionally the renal mass may be so large as to impede delivery. A
TABLE 1.
Findings by Intravenous in
the
Upon palpating an abdominal mass in the newborn period, the physician must also consider hydronephrosis, neuroblastoma, Wilms’ tumor, and true polycystic kidney of the infantile type. Multicystic renal dysplasia rarely occurs bilaterally; when it does, stillbirth is inevitable since the kidneys contain no functioning glomeruli. The earlier an abdominal mass is detected after birth, the more likely is the diagnosis to be multicystic renal dysplasia. Intravenous urography (Table 1) is most helpful in the diagnosis of abdominal masses in children. With multicystic renal dysplasia, the renal size is enlarged on the plain film of the abdomen. Usually, nonvisualization of contrast material in the collecting system occurs because of few or no functioning
glomeruli although rarely a multicystic kidney excrete contrast material, thereby confusing the differentiation between a multicystic kidney and a hydronephrotic kidney. will
At cystoscopy, the ureteral orifice on the affected side may be absent. When the ureteral orifice is present, retrograde ureterogram will demonstrate a ureter terminating blindly below the ureteropelvic junction. In
the renal size is enlarged, or nonvisualization of contrast material depending on the degree of cortical atrophy. Should there be sufficient renal cortex to excrete the contrast material, marked pyelocalyceal dilatation will be evident. In neuroblastoma, stippled calcification is found in 50 per cent of the masses, along with excellent visualization of contrast material in normal pyelocalyceal systems. When the
hydronephrosis,
with either decreased
Differential Diagnosis of Abdominal Masses in
Claildrera
Key: + = Present. 0 = Absent. I = Decreased.
899
arises from near the adrenal, the kidney is displaced inferiorly with lateral displacement of the superior pole. When the tumor arises from the sympathetic chain, the kidney and ureter are displaced laterally. With %Vilms’ tumor, there is usually prompt appearance of contrast material in an enlarged kidney with marked attenuation and distortion of the pyelocalyceal system. Rarely does invasion and obstruction of the renal vein occur; when it does, the intravenous urogram will demonstrate a nonfunctioning tumor
kidney. In polycystic renal disease of infancy, there are bilateral enlarged kidneys with decreased visualization of contrast material. When visualized, the excretion pattern may be in a sun ray or streaked pattern in the dilated collecting ducts, and the calyces are often not Newborns with infantile polycystic seen. disease (Type 1 of Potter) invariably die in the neonatal period of renal insufficiency and have cystic alterations of the liver as well.
by others.14 Three patients also had atresia. biliary In four patients, the contralateral kidney was found to be hydronephrotic. Three of these four children also had severe congenital anomalies, and died soon after their initial evaluation. Stenosis of the ureteropelvic junction was the cause of hydronephrosis in two of these children. The prognosis of contralateral hydronephrosis~erse is not necessarily serious unless it is massive and/or accompanied by other severe malformations.15 served
References 1.
masses
1958. 2. Kissane,
and Smith, M. G.: Dysplasia in and of Infancy and Childhood. St. Louis, C. V. Mosby Company, 1967,
J. H., of
Infancy
p.526. 3.
malformations. In Pathology of R. H. Heptinstall Ed., Boston. Little, Brown, and Company, 1966, p. 75. Ericsson, N. O., and Ivemark, B. I.: Renal dysplasia and pyelonephritis in infants and children. Arch. Pathol. 66: 255, 264, 1958. Gleason, D. C., McAlister, W. H., and Kissane, J. H.: Cystic disease of the kidneys in children. Am. J. Roentgenol. 100: 135, 1967. Pasternack, A.: Microscopic structural changes in macroscopically normal and pyeionephrotic kidneys of children. Ann. Paediatr. Fenn. Suppl. 14, 1960. Bernstein, J.: Developmental anomalies of the renal parenchyma: renal hypaplasia and dysplasia. In Pathology Annual, Sommers, S. C., Ed. New York, Appleton-Century-Crofts, Inc., 1968, p. 213. —, and Meyer, R.: Congenital abnormalities of the urinary system. II. Renal cortical and medullary necrosis. J. Pediatr. 59: 657, 1961. R.: Experimental study of renal and
—:
the
4.
5.
900
L. A., and Martin, L. W.: Abdominal in the newborn infant. Pediatrics 21: 596,
Pathology
Treatment, Outcome, and Prognosis
Nephrectomy is the treatment of choice for unilateral renal dysplasia. Dysplasia is not a progressive disease that will eventually affect the other side. Surgical exploration will also rule out the rare possibility of a poorly functioning Wilms’ tumor from renal vein occlusion. Our patients demonstrate the favorable prognosis of this condition when it occurs as an isolated malformation. Ten of the 12 patients without coexisting anomalies have done well since their nephrectomies. The remaining two patients had been admitted with serious attendant disease: one with fever and sepsis and the other, an immature infant of 27 weeks gestation, with severe apnea and respiratory distress. Both succumbed shortly after being hospitalized. Accompanying congenital anomalies are ominous prognostic signs. Nine of ten infants with multiple congenital anomalies died by the age of three months. In our series, congenital heart lesions and gastro-intestinal atresias were common (four each). This has been ob-
Longino,
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Congenital
Kidney,
—,
Meyer,
parenchymal maldevelopment (renal dysplasia). Washington, D.C., 3rd International Congress of Nephrology, September 1966. Safouh, M., Crocker, J. F. S., and Vernier, R. L.: Experimental cystic disease of the kidney. Lab. Invest. 23, 392, 1970. Hildebrand, O.: Weiterer Beitrag zur Pathalogischen Anatomic Der Nierengeschwulste. III. Congenitale Cystenniere nut Sarkombildung Arch. F. Klin. Chir. 48: 343, 1894. Osathanondh, V., and Potter, E. L.: Pathogenesis of polycystic kidneys. Type 2 due to inhibition of ampullary activity. Arch. Pathol. 77: 549, 1946. Potter, E. L.: Normal and Abnormal Development of the Kidney. Chicago, Year Book Medical Publishers, Inc., 1972, p. 154. Arey, J. B.: Cystic lesions of the kidney in infants and children. J. Pediatr. 54: 429, 1959. Pathak, I. G., and Williams, D. I.: Multicvstic and cytstic dysplastic kidneys. Br.J. Urol. 36:318, 1963.
