Seminars VOL.

in Roentgenology

X, NO. 2

APRIL

1975

Letter From the Editor

I

N 1962, I ENCOUNTERED a strange and fascinating case of unilateral multicystic kidney. This newborn boy presented with a huge asymptomatic mass in the region of his left kidney. Intravenous urogram demonstrated a normal right urinary tract, but the left excretory system did not opacify. A number of faint thin curvilinear shadows appeared within the mass soon after the contrast injection and disappeared slowly over the next half hour. The mass was resected and showed the typical “bunch-of-grapes” appearance of multicystic kidney. The ureter had an atretic segment about 2 cm below the pelvis. No renal artery was found at operation. I “borrowed” the unopened kidney, injected contrast medium into the ureter just above the atretic zone, and then radiographed the specimen. To my surprise, all the cystic structures were opacified, indicating that they intercommunicated and were in continuity with the ureter. Further, they were arranged in the form of a pelvis and its calyces, tremendously dilated, but with no recognizable cap of parenchymal renal tissue (see Fig. 5, p. 116. I recalled having seen a similar newborn urogram several years earlier, and looked up the case. Fortunately, the roentgenograms and gross pathologic specimen were still available (see Fig. 6, p. 117). Again, the curvilinear shadows were visible on the urogram; again, the gross specimen presented the bunch-of-grapes appearance, with ureteral atresia and inapparent renal artery; again, intercommunication between the cysts was demonstrated; again, the cysts seemed to be arranged like a huge pelvicalyceal system without evidence of overlying parenchyma! Some years later, Dunbar and Nogrady described multiple crescentic shadows identical to the curvilinear shadows in my two patients. They attribSeminars

in Roenfgenology,

Vol. X, No. 2 (April),

1975

uted the crescents to compression of contrastladen renal tubules by dilated calyces and considered them diagnostic of severe hydronephrosis. To explain these calyceal crescents in my patients, the multicystic kidneys, despite their translucency and oligemia, had to have enough parenchyma and enough circulation to permit excretion of contrast medium. I went on a histologic safari and found small herds of glomeruli grazing in groves of tubules and blood vessels along the shores of the cysts. Putting all this together, I concocted the following theory: (1) Unilateral multicystic kidney represents severe hydronephrosis of the fetal kidney in which the parenchyma is so attenuated that it becomes translucent, and the dilated pelvis and calyces show through as grapelike cysts. (2) The cause of the hydronephrosis is the ureteral obstruction so consistently associated with it. (3) The diminutive or absent renal artery is either the result of sparse renal parenchyma or of thrombosis of the renal artery during fetal life. The latter might even be responsible for the ureteral atresia. (A similar explanation for atresia of the gut is now widely accepted.) (4) The dysplasia of the renal parenchyma, almost always evident histologically, is the result of maldevelopment of the cellular structures in the metanephros, caused by the ureteral obstruction. My theory explained those cases of multicystic kidney with intercommunicating cysts, but what about the well-documented noncommunicating cases?Unable to carry my own views any further, I enlisted the support of Dr. Leo J. Cussen, then a pediatric pathologist at Cincinnati Children’s Hospital. Our study of 18 cases of multicystic kidney are the basis for the article on page 113. Recently Dr. Jerome Wiot, Assistant Editor, and I decided that a Seminar on Renal Cystic 93

94

Disease would be timely, and organized this issue. The “Future Issues” notice was seen by Dr. N. Thorne Griscom, who volunteered a manuscript that he and his colleagues at Boston Children’s Hospital had recently completed. When I looked it over, I gulped and reached for the phone. Here was the explanation for the noncommunicating

LETTER

FROM

THE

EDITOR

form of multicystic kidney! Their article appears on page 125. I believe that the two articles together clarify the nature of unilateral congenital multicystic diseaseof the kidney. Benjamin Felson, M.D. Editor

Seminars in roentgenology.

Seminars VOL. in Roentgenology X, NO. 2 APRIL 1975 Letter From the Editor I N 1962, I ENCOUNTERED a strange and fascinating case of unilateral...
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