Milton Elkin

Cystic diseases of the kidney—Radiological and pathological considerations

Cysts of the kidney are of differing etiology, progress and clinical significance. Some may be clearly distinguished by radiological examination—polycystic disease of childhood, adult polycystic disease, simple cortical cysts, medullary sponge kidney, medullary necrosis, pyelogenic cysts, inflammatory cysts, cysts of calculous disease, neoplastic cysts, parapelvic cysts, and perinephric cysts. In others, radiological studies may be of inferential help—multicystic kidney, polycystic disease of the newborn, trisomy syndrome, tuberous sclerosis complex, medullary cystic disease. A classification of renal cysts is presented, with pathologic description.

Renal Blood Flow and Renin Activity in Renal Venous Blood in Essential Hypertension

The intrarenal distribution of blood flow measured by the133xenon washout method and the renin activity of renal venous blood were determined in 16 patients with early essential hypertension. None of the patients had evidence of systemic disease except for the elevation in blood pressure (> 150/100 mm Hg). Fifteen of the subjects received a controlled sodium diet during 7 to 9 days before study, at the time of renal angiography. An inverse relationship was noted between the cortical component of the renal blood flow and renin activity of renal venous blood (r = 0.64, P < 0.02). Renin secretion rates were also calculated in 12 patients confirming the inverse relationship between cortical distribution of blood flow and renin secretion (r = 0.763, P < 0.01). The cortical renal blood flow in 10 patients on a low salt intake was 79.6% ± 2.6 (SE) of the total renal blood flow. The cortical blood flow in five patients on a high salt diet was 87.6% ± 1.9 (SE); the statistical difference between the two groups is significant (P < 0.05). A direct relationship was noted between cortical blood flow and the logarithm of the 24-hour urinary sodium excretion from the day preceding the study (r = 0.54, P < 0.05). Renin secretion rate and renin in renal venous blood were directly correlated (r = 0.813, P < 0.01). Changes in corticomedullary distribution of flow were inversely related to the changes in cortical distribution. The degree of reduction of cortical renal blood flow correlated with the degree of increase in renin secretion and in renin activity in renal venous blood. Our data are compatible with reduced cortical renal blood flow mediating renin release or vice versa. Either mechanism would result in more efficient conservation of salt and water by the kidney.

Renal vascular shunts

Most renal arteriovenous fistulae are acquired. In addition to the haemodynamic consequences of any left to right shunt, these lesions can be responsible for systemic hypertension. Traumatic fistulae are being reported more frequently, especially following percutaneous renal biopsy. The existence of the Oxford shunt (Trueta) is still open to question, with no reported confirmation angiographically of such a phenomenon in man. The world literature of renal arteriovenous fistulae is reviewed and several new cases are added.

Diagnostic value of the psoas shadow.

Summary Absence or diminution in clarity of one of the psoas lines has been reported as an aid in the diagnosis of a variety of intra-abdominal and retroperitoneal lesions. Review of single and multiple abdominal films of 200 “normal” patients has shown unequal visualisation of the psoas lines in about 25 per cent on the single study and 11 per cent on multiple study. 7.5 per cent showed absence of one psoas line on single study and 2.5 per cent on multiple study. Although the magnitude of these figures will expectedly vary from series to series, they do indicate that the psoas lines may show differential appearance “normally.” The appearance of the psoas lines is generally not helpful in differentiating intraperitoneal from retroperitoneal masses or in the diagnosis of peritonitis. Intraperitoneal fluid, such as blood from laceration of the spleen, will not selectively obliterate the left psoas line. Retroperitoneal haemorrhage, however, will frequently obliterate the psoas line. Hence, absence of the psoas shadow in patients with injury to the spleen suggests associated retroperitoneal haemorrhage as from laceration of the kidney. Visualisation of the psoas line may be present even with retroperitoneal infection.

Renal Cystic Disease- An Overview

T HERE HAVE BEEN a number of classifications of renal cysts,2p6 and more will undoubtedly appear, indicating weaknesses in those already proposed. The major advantage of classification is to clear up the many confusions in terminology of the various types of renal cystic disease. It is not uncommon to see a report describing a condition in terms which in another classification refer to a different entity. This confusion is ascribable not only to the nephrologist and radiologist, but also to the usually accepted “final judge,” the pathologist. I recently read the report of a surgical specimen rendered by an excellent pathologist with the following diagnostic terms used interchangeably: multilocular cystic kidney, multiple cysts of the kidney, and multicystic kidney. These are all different entities, as will be demonstrated later in this Seminar. Purupelvic cyst is an extrarenal lesion, occurring most frequently in the renal hilum; peripelvic cyst is another name for pyelogenic cyst or calyceal diverticulum. The sponge kidney of the infant is polycystic disease of the newborn; medullary sponge kidney is seen usually in the adult and consists of ectasia of the collecting ducts. Classification consists in groupings of conditions with some sort of common or related denominator. If causes were known, an etiologic classification would be satisfactory-eg, cysts due to obstruction, cysts due to underlying vascular disease, cysts due to infection, etc. However, the etiology of most renal cysts has not been clearly established. For congenital cysts, specific embryologic developmental defects might serve as the basis for classification. Again, there is no agreement on the nature of the defects, and a classification of this sort would leave too many renal cysts unclassified. A pathologic classification based on histologic criteria has not been feasible because the histologic changes are, for the most part, not specific enough. A clinical classification, using such parameters as age of occurrence, or of death, the presence of hypertension, or of renal insufficiency, or