Cystic diseases of the kidney—Radiological and pathological considerations

C/in. Radiol. (1969) 20, 65-82 CYSTIC DISEASES OF THE KIDNEY-RADIOLOGICAL AND PATHOLOGICAL CONSIDERATIONS MILTON ELKIN and JAY BERNSTEIN

From the Departments of Radiology and Pathology, Albert Einstein College of Medicine-Bronx Municipal Hospital Center, Bronx, New York 10461 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,parappelvic 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.

THE terminology of cystic abnormalities of the kidney is confusing and studies have been hampered by a lack of clear definitions. Particularly, the genetic investigation of polycystic disease has been severely retarded by the lack of a satisfactory pathologic classification. Certain morphologic similarities have tended to obscure differing patterns or morphogenesis and differing clinical manifestation. A few examples of nomenclatural choas may be cited. The designations of"multicystic" and "multilocular cystic" have both been applied to the condition of multiple simple cortical cysts. "Peripelvic cyst" has referred in some instances to a parenchymal cyst communicating with a calyx (pyelogenic cyst) and in other instances to a non-communicating cyst in the region of the renal pelvis (parapelvic cyst). Types of medullary cysts often not clearly delineated include: true meduallary cystic disease, medullary sponge kidney, medullary tubular ectasia, and papillary necrosis of the "medullary" type. The term "sponge kidney" has been used in reference both to infantile polycystic disease and to one of the cystic conditions of the medulla. The practice of regarding all kidneys that contain cortical cysts as "polycystic" does not appear to be justified. Cysts of the renal parenchyma may be encountered in conditions that are clearly acquired rather than developmental (e.g., arteriolar nephrosclerosis) and in conditions in which they appear to be secondary to another abnormality (e.g., tubular cysts in the congenital nephrotic syndrome). Cysts do not appear to be of specific pathogenic significance, and they may develop in normally formed, dysplastic or scarred nephrons.

The following classification of cystic conditions is based on clinical, genetic and morphologic considerations of congenital abnormalities (Bernstein and Meyer, 1967) as modified to incorporate certain radiological-pathological correlations (Table 1). TABLE 1 CLASSIFICATIONOF RENAL CYSTS

I. Renal A. B. C.

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Dysplasia Multicystic kidney Focal and segmental cystic dysplasia Multiple cysts associated with lower urinary tract obstruction II. Polycystic Disease A. Infantile polycystic disease 1. Polycystic disease of the newborn 2. Polycystic disease of childhood a. Congenital hepatic fibrosis b. Medullary tubular ectasia B. Adult polycystic disease III. Cortical Cysts A. Trisomy syndromes B. Tuberous sclerosis complex C. Simple cysts 1. Solitary 2. Multiple D, Multilocular cysts IV. Medullary Cysts A. Medullary sponge kidney B. Medullary cystic disease C. Medullary necrosis D. Pyelogenic cyst V. Miscellaneous Intrarenal Cysts A. Inflammatory 1. Tuberculosis 2. Calculous disease 3. Echinococcus disease B. Neoplastic- cystic degeneration of'carcinoma C. Traumatic-intrarenal hematoma VI Extraparenchymal Renal Cysts A. Parapelvic cyst B. Perinephric cyst

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RENAL DYSPLASIA The term "renal dysplasia" is used to signify embryologic maldevelopment of the kidney (Ubelhor, 1933; Baggenstoss, 1951). Implicit in this expression are developmental arrest and abnormal differentiation. The concept of dysplasia has evolved to encompass focal abnormalities as well as grossly malformed kidneys (Pasternack, 1960). Several histologically abnormal nephronic and ductular structures are present in dysplastic kidneys (primitive and fetal glomeruli, primitive tubules, and primitive ductules), but only primitive ducts (Ericsson and Ivemark, 1958) and metaplastic cartilage (Voth, 1961) can be taken as indisputable evidence of congenital maldevelopment, the others also being seen as a consequence of postnatal parenchymal disease (Bernstein and Meyer, 1967). Cysts in dysplastic kidneys may be of glomerular, tubular, ductular, or ductal origin. They have been shown by microdissection studies to arise as localized dilatations within completely formed nephrons, where they may be associated with epithelial kyperplasia (Baxter, 1965; Osathanondh and Potter, 1964). Several types of dysplastic kidneys have been recognized, and among them are two that are grossly cystic: (1) the multicystic kidney, and (2) multiple cysts associated with lower urinary tract obstruction. MULTICYSTIC KIDNEY.--The multicystic kidney is one extreme of a spectrum of severe corticomedullary dysplasia that also includes the small "aplastic" kidney. The essential features are severe disorganization with nephronic structures in disarray, incomplete corticomedullary differentiation, poorly developed lobar structure, histologically apparent maldevelopment in the form of primitive ducts and metaplastic cartilage, and variable cyst formation. The affected kidney lacks any resemblance to a normal kidney (Schwartz, 1936; Fine and' Burns, 1959). Other names applied to this condition include: aplasia with cystic degeneration, cystic hypoplasia, congenital cystic hydrocalycosis, unilateral polycystic disease, and cystic hamartoma. It has also been confused with multilocular cysts and multiple simple cysts. The condition is not familial and is not related to infantile polycystic disease. Most studies have been based on surgical cases, and the unilateral nature of the lesion has been emphasized. It must be remembered, however, that bilateral multicystic dysplasia is encountered in the newborn, in whom it seems to be the most common, single form of cystic disorder. It often occurs as one of multiple congenital anomalies. Bilateral involvement is a cause of renal nonfunction, and like

agenesis it may be associated with abnormal facies. The unilateral lesion has been accorded a good prognosis, the other kidney by consensus being normal (Spence, 1955; Arey, 1959). Pathak and Williams (1963) have, however, emphasized the frequency of contralateral hydronephrosis or hypoplasia in young infants. Parkkulainen, Hjelt, and Sirola (1959) have also indicated that the prognosis may be impaired by other congenital anomalies. Certainly the state of the other kidney must be evaluated, but multicystic dysplasia is not in itself a progressive disease that will eventually affect the opposite side; a favorable outcome can be anticipated when the abnormality is discovered in older children and in adults. Atresia of the ureter and occlusion of the renal pelvis are characteristically seen (Pathak and Williams, 1963; Rubenstein, Meyer and Bernstein, 1961), although patency has been described in a few ' instances (Vellois and Garrett, 1961). The blood supply is variable and the hilar vessels are usually quite small. The kidney is irregularly deformed and enlarged by cysts, some masses weighing as much as several hundred grams (Fig. 1). Others are quite hypoplastic and are distinguishable from aplastic kidneys only by the presence of cysts. The cysts vary in size from a few millimeters to several centimeters in diameter. Their walls are of fibrous tissue with a lining of low cuboidal or flat epithelial cells and most specimens contain a relatively solid central area, in which nephronic, ductal and dysplastic elements are present (Fig. 2). Rudimentary lobar development is usually detectable as aggregates of primitive ducts and adjacent caps of metanephric tissue (Ljungqvist, 1965). Microdissection studies have demonstrated isolated cysts (Bialestock, 1960),

Fro. I Multicystic kidney. T h e case o f a n e w b o r n i n f a n t with u n i l a t e r a l f l a n k m a s s a n d n o n v i s u a l i z a t i o n b y excretory u r o g r a p h y . T h e k i d n e y has been bisected to s h o w the relationship o f gross cysts to a central core o f relatively solid tissue. T h e u r e t e r w a s atretic.

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Urograms show that the abnormal kidney fails to excrete contrast medium. MULTIPLE

FIG. 2 Multicystic kidney. Photomicrograph of solid tissue compressed by 3 adjacent cysts, showing both evidence of dysplasia and readily recognizable metanephric tissue (MT). The latter includes glomeruli and convoluted tubules. Evidence of dysplasia is present in the form of numerous small primitive ducts (PD), some of them dilated, which are surrounded by fibromuscular collars and which represent abnormally developed branches of the metanephric duct (primitive ureter). Magn. 40 × H & E stain.

cysts arising as terminal dilatations of collecting tubules (Osathandh and Potter, 1964), and lack of connection between distal convoluted tubules and collecting ducts (Bialestock, 1960). Osathanondh and Potter (1964) believe the malformation may be related to diminished branching of collecting tubules and deficient nephronic development. The condition is most often discovered as a lobulated, non-tender, movable abdominal mass in otherwise healthy infants and children. On occasion it has been associated with pressure symptoms, abdominal or flank pain, and vague intestinal complaints. Male patients outnumber females, and the lesion is somewhat more common on the left. Extreme enlargement in early life has been known to cause fetal dystocia. In patients who do not have a palpable mass, the abnormality may go unrecognized to adult life. Calcification or even ossification of cyst walls in older individuals may produce radiopaque rings in the mass. Urinalysis is usually normal, and occasional reports of pyuria probably reflect inflammatory disease in the opposite kidney. Associated hypertension has rarely been reported.

CYSTS

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URINARY TRACT OBSTRUCTION.--Cystic dysplasia of the renal cortex is a relatively common complication of severe lower urinary tract obstruction in young infants, often vitiating surgical relief of the obstruction (Pathak and Williams, 1963; Rattner, Meyer and Bernstein, 1963). It is most severe in and often limited to the peripheral cortex, a distribution suggesting that its pathogenesis is related to the effect on the developing kidney of severe urinary tract obstruction during fetal life. Osathanondh and Potter (1964) have suggested that the relatively short and straight collecting tubules transmit increased hydrostatic pressure to the growing ampullary ends of these ducts, resulting in terminal cystic dilatation. The abnormality is seen most often in infant boys with severe obstruction due to posterior urethral valves, and it is rarely observed in older individuals with less severe congenital obstruction (Rattner, Meyer, and Bernstein, 1963). Complete obstruction due to urethral atresia is associated with more severe dysplasia. Severe enough dysplasia may be responsible for nonfunction. Radiographic study may demonstrate soft tissue masses representing the dilated urinary bladder and enlarged kidneys. Intravenous urography shows hydronephrosis and hydroureter bilaterally if there is enough renal function to allow excretion of the contrast medium. In our experience the cysts cannot be demonstrated radiographically, although we have not had the opportunity to perform angiography in such patients. POLYCYSTIC DISEASE In general, polycystic disease is classified into the infantile and adult types. The relationship of the two remains in question despite more than a halfcentury of speculation. Other than certain morphologic similarities, much of the evidence suggests that the two conditions are not related. INFANTILE POLYCYSTIC D I S E A S E . - - P o l y c y s t i c d i s e a s e in childhood falls into two general forms: (1)

the large, spongy kidneys seen principally in newborns and associated with cystic lesions in the liver and other viscera; and (2) a heterogeneous group seen in later childhood, including those presenting with liver disease and portal hypertension, designated as "congenital hepatic fibrosis", and also those children with progressive renal insufficiency and medullary tubular ectasia. In the first abnormality, marked dilatation of nephrons and collecting ducts leads to great renal

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FIG. 3 Infantile polycystic disease. Newborn infant with bilaterally palpable kidneys and anuria. The cortex is diffusely spongy and contains scattered gross cysts. The medulla is the site of marked tubular ectasia, which presents as grossly visible, irregularly sized, discrete cysts.

FIG. 4 Infantile polycystic disease. Newborn infant with bilateral, palpable flank masses and elevated BUN. Fifteen-minute film of the urogram shows enlarged slightly irregular kidneys with no pyelogram but a mottled nephrogram. The multiple small radiolucencies represent the numerous cysts, confirmed at operation.

enlargement. The kidneys are diffusely enlarged However, a nephrogram may be produced, showing and the numerous small cysts (few millimeters in more clearly the enlarged kidneys as well as multiple diameter) have a relatively uniform appearance radiolucent mottlings representing the non-opacified (Fig. 3). Microdissection studies (Baxter, 1965; numerous small cysts (Fig. 4). Osathanondh and Potter, 1964) have indicated that The second type of infantile polycystic disease is the most common site of dilatation is in the collect- grouped more for convenience than clinical or ing tubules, although portions of the nephron are pathologic homogeneity, and clinical-pathological also involved and glomerular dilatation may be study has been hampered by the lack of a uniform apparent on histologic examination. The cysts are system of classification and nomenclature. Some lined by tubular or poorly differentiated cuboidal of these children manifest signs of renal insufficiency epithelium. Medullary involvement is characteristi- at an early age and are principally problems in cally present, and ectasia of collecting ducts may be chronic renal failure. Others present with portal seen at the papilla. hypertension, and their renal disease is of secondary The majority of affected liveborn infants die in importance. Nephronic and ductal involvement are the first few days of life. Those surviving longer can both present, although cyst formation is not so develop hypertension with left ventricular hyper- diffuse as in the neonatal variant. The kidneys are trophy, electrocardiographic features of left ventri- usually large but smooth in contour, retaining the cular strain, and cardiac failure. The condition normal reniform shape (Fig. 5). Medullary cysts appears either sporadically or in more than one are quite characteristically seen (Fig. 6), and sibling of a single generation. This pattern of excretory urography shows a normal pelvicalyceal horizontal familial transmission suggests that the system with medullary tubular ectasia, radiographiaffected gene behaves as an autosomal recessive cally resembling medullary sponge kidney (Lathrop, (Dalgaard, 1957; Lundin and Olow, 1961). 1959; Reilly and Neuhauser, 1960; Kerr, Warrick The condition is always bilateral and the usual and Hart-Mercer, 1962). Chronic pyelonephritis is reniform appearance of the kidneys and usual a common complication and may contribute to anatomic landmarks are preserved. The numerous renal failure. The hepatic lesion consists of portal small cysts give the kidney a spongy appearance. fibrosis with variable bile duct proliferation and Calyceal and pelvic distortion are uncommon, but ectasia. Lesions in the liver lead to portal hypertenmay result from increased bulk of the surrounding sion. A principal clinical symptom is bleeding from tissue. esophageal and gastric varices in childhood or Radiographically large kidneys may be seen on early adult life. The condition appears to be the abdominal film. Renal function is almost familial. always too poor to afford visualization of the ADULT POLYCYSTIC DISEASE.--Polycystic disease pelvi-calyceal system by intravenous urography. in adults is characterized by irregularly-sized cysts

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FIG. 5 Polycystic disease. A 5-year-old child with chronic renal failure. Medullary tubular ectasia is grossly apparent. The liver was cirrhotic, with severe portal fibrosis. This is the type of case often designated as 'congenital hepatic fibrosis'. (See Fig. 6.)

FIG. 7A Adult polycystic disease. A--Grossly cystic and deformed kidney in the case of a 54-year-Md patient. The cysts vary in size and disposition, and they involve both cortex and medulla. The kidney is enlarged, and the pelvis is distorted. Polycystic disease of the liver was also present. •--Nephrotomogram shows the many cysts of variable size in the left kidney (arrows). Similar findings are present in the right kidney, demonstrated at other levels of the tomogram. The enlarged liver is also slightly opacified by the high blood level of contrast medium due to the large intravenous dose; the several relative radiolucencies in the liver (arrows) represent multiple hepatic cysts. The demonstration of liver cysts in association with multiple renal cysts establishes the radiographic diagnosis of polycystic disease of the kidneys.

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FIG. 6 Polycystic disease. Same case as Fig. 5. Lowpower photomicrograph showing marked medullary tubular ectasia. There is also cystic dilatation of cortical nephrons, demonstrating that the disease is not limited entirely to the medulla. Magn. 9 × H & E stain.

Fro. 7a

of nephronic origin, both cortical and medullary in location with intervening normal renal tissue (Fig. 7). The disease is bilateral, thougll not necessarily symmetrical. The cysts, which vary considerably in size, may contain blood, serous fluid or urine. The condition usually becomes clinically apparent in the fourth decade, although cases have

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FIG. 8B

FIG. 9 Infantile cystic nephrosclerosis. The superficial cortex is studded with smaller tubular and glomerular cysts in the ca~ of a young infant with trisomy D and multiple congenital anomalies. Cystic structures retain a 'primitive' appearance, and involutional changes are also present. Magn. 42 × H & E stain.

FIG, 8C Adult polycystic disease. A 29-year-old female with hypertension (130/95), normal BUN and dull discomfort in the left flank. A--The intravenous urogram shows both kidneys to be enlarged. with stretching of several of the infundibula. B--Aortogram shows two main renal arteries on the right side and three on the left. The intrarenal arteries are stretched and displaced by the many cysts, c - - T h e nephrographic phase of the aortogram shows numerous radiolucencies of various sizes representing the cysts of the right kidney. The left kidney had the same appearance.

been described in quite young children ("adult form of polycystic kidneys in children"). The peak death rate occurs between the ages of forty and sixty. The familial character of the disease is quite typical with repetition in several generations, the so-called vertical genetic transmission characteristic of an autosomal dominant mode of inheritance.

Clinically there are usually large flank masses in the presence of hypertension, proteinuria, and various formed elements in the urine, including erythrocytes, leukocytes and casts. The patients develop the usual signs of progressive chronic renal failure. Radiographic study shows large, lobulated renal masses with deformities of the pelvicalyceal systems due to pressure of the cysts on the calyces and infundibula (Fig. 8a). On angiographic studies there is displacement of the intrarenal vessels by the numerous cysts (Fig. 8b). The nephrogram may show diffuse mottling due to the areas of non. opacification at the sites of the many cysts of various sizes (Fig. 8c). The chief differential diagnostic problem is multiple simple cysts. However, simple cysts are usually few in number, often with involvement 0f only one kidney, and the process is usually not pro. gressive or only minimally so. There is less destruction of renal substance, lack of renal insufficiency and hypertension, and an absence of a family history of kidney disease.

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CORTICAL CYSTS Multiple cysts in the cortex of the kidney are encountered in several conditions that cannot be regarded as either polycystic disease or renal dyslasia. Despite several morphologic similarities, iPtshould not be expected that they necessarily have common pathogenic backgrounds. The indiscriminate practice of applying the term "polycystic" to

THE

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this miscellany of dissimilar conditions has no more than descriptive meaning. TRISOMY S Y N D R O M E S . - - N u m e r o u s small cysts studding the capsular surfaces of the kidney and outlining the fetal fissures are associated with trisomy syndromes (Fig. 9) and are seen in young infants with congenital heart disease (Bartman and Barraclough, 1965). The cysts are usually small,

FIG. 10A

FIG. 10a

FIG. 10e

FIG. 10D

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FIG. 10B Tuberous sclerosis. Four-month-old boy with seizures. Diagnosis was tuberous sclerosis. Right flank mass felt at examination. (A)--Intravenous urogram shows compression of the lower calices of the right kidney by a mass, with flattening of the upper calices also. (B)~Tomogram more clearly demonstrates the large, round mass at the lower pole, deforming the calices and pelvis as well as displacing the upper ureter medially. (c)--Retrograde pyelogram again shows the compressed lower caliees due to a largecyst ofthelowerpole. (D)--Laterin the retrograde study there is opacification ofalargecyst of the upper pole. The pressure ofretrogradeinjectioncausedruptureofacalyxintothecyst. (E)--At operation many renal cysts were found. Photomicrograph showing portion of cyst wall removed from superficial cortex. The cysts are lined by hyperplasti~ columnar epithelial cells, resembling proximal tubular epithelium. Nephronic atrophy and slight fibrosis are present in the tissue compressed by the cysts. A portion of fibrous renal capsule is present to the left. Magn. 130× H & E stain.

and specific clinical and functional abnormalities have not been recognized. However, extensive involvement or marked enlargement of the cysts could lead to functional impairment. TUBEROUS SCLEROSIS C O M P L E X . - - R e n a l cysts in the tuberous sclerosis complex are usually small, although they can on occasion be quite large and measure several centimeters in diameter (Arey, 1959). The cysts are generally of tubular origin, being lined by recognizable tubular epithelium or by hyperplastic cells. Cortical cysts, large enough to produce radiographic distortion and renal enlargement, have been described by Engstrom and associates (Engstr6m, Ljungqvist, Persson, and Wetterfors, 1962) and we have had such a case (Fig. 10). Although surgical removal or decompression of large cysts has sometimes resulted in some clinical

amelioration, the condition is progressive. Renal function and prognosis depend on the degree of involvement and the amount of available normal tissue. Severe involvement leads to renal failure and hypertension. SIMPLE CYSTS.--At one time simple renal cysts were considered clinically to occur infrequently (Glaser, 1952). Now, with better methods of radiographic evaluation (higher doses of more opaque media during intravenous urography, nephrotomography and renal angiography), these cysts are discovered easily and commonly. Solitary cysts have been described in both children and adults; they are a rare finding in infants. They may be congenital, but cysts in older individuals are more likely to be acquired abnormalities. Nephrosclerosis is one cause of multiple cysts in elderly patients. Although

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FIG. 11 FIG. 12 Fl~- 11--Solitary renal cyst. A single cyst discovered incidentally at autopsy in an 85-year-old patient with cerebral vascular occlusion. Cortical tissue is pushed up around the cyst, forming the "beak" that is apparent radiographically. The capsular surface of the kidney has a granular appearance, and microscopic examination disclosed arteriolar nephrosclerosis. A few other very small cysts can be seen on the capsular surface of the kidney, but diffuse cystic disease is not present. FIe. 12~Multiple Simple Cysts (Cystic nephrosclerosis). Numerous cysts in the cortex and medulla of a 46-year-old patient with glioblastoma multiforme. Cysts are irregularly present throughout the kidney, but diffuse involvement is not seen. Numerous areas of relatively normal cortex are free of cysts. One large cyst appears to attenuate and distort the renal pelvis.

A FIG. 13 B Solitary simple cyst. A 60-year-old woman with hypertension for at least three years. (A)--Intravenous urogram shows a large mass occupying the lateral aspect of the right kidney, causing extensive pressure deformity of the pelvicaliceal system. (B)--The selective renal angiogram demonstrates the mass to be avascular with displacement of surrounding vessels. The nephrogram shows sharp outward displacement of the renal cortex at the margins of the mass, the "lip" or "beak" sign of a renal cyst.

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Fie. 14B

referred to as solitary, they are often multiple in a single kidney and may be found in both kidneys. At autopsy, simple cysts rarely occur singly. Simple cysts arise in the renal parenchyma, usually in the cortex (Figs. 11 and 12). They are unilocular and they characteristically do not communicate with the renal pelvis except in the rare instance of spontaneous rupture into the pelvicalyceal system (DeWeerd and Simon, 1956). The cyst walls are thin or fibrous and lined by low cuboidal or flattened epithelium. The cyst is filled usually with a serous fluid rather than urine. Although the simple cyst usually causes pressure deformity of the calyceal system, it may not encroach on the calyces but appear radiographically as a circular soft tissue mass overlying the renal margin or projecting from it. Occasionally there is calcification of the cyst wall, which typically presents on x-ray as a thin, curved line of calcification; however, a similar type of calcification can be visualized in renal neoplasms. Rarely the calcification in the wall is mottled, simulating the type of calcification seen in renal malignancies. The cysts do not opacify

during urography but appear as a kidney mass or masses, distorting the pelvicalyceal system or renal border (Figs. 13 and 14). The simple cyst is sometimes large enough to produce discomfort and to be discovered on physical examination as a palpable abdominal mass, but most are asymptomatic and are discovered during urographic study for other conditions. Although hematuria has been occasionally ascribed to their presence, simple cysts usually produce no urinary abnormalities. MULTILOCULARCYsTs.--Multilocular renal cysts are rare lesions. They are unilateral, circumscribed, cystic masses, which can present as abdominal tumors (Powell, Shackman and Johnson, 1951). Some cases reported as unilateral polycystic disease seem to be examples of this unusual abnormality. The cystic masses, which are encapsulated, are made up of loculi varying greatly in size and lacking communication with each other or with the renal pelvis. The septa consist of compact fibrous tissue and smooth muscle lined by columnar or flattened epithelium. The septa usually do not contain

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FIG. 15 Medullary sponge kidney. A 22-year-old female with intermittent hematuria and pyelonephritis for five years. (A)--Plam film of the abdomen shows multiple small calculi in the medullary portion of the right kidney. (n)--lntravenous urogram demonstrates typical appearance of medullary sponge kidney on the right with collections of opacified urine in the dilated collecting ducts. The left kidney appears normal except for suggestive deepening of calyceal cupping.

mature renal tissue, although rudimentary nephronic elements have been described. Except for atrophy and distortion due to ccmpression by the cystic mass, the rest of the kidney is normal. The urogram shows distortion of the calyceal system due to pressure; the appearance is the same as with a simple cyst. This abnormality may be regarded as a cystic hamartoma or possibly a benign neoplasm ("benign multilocular cystic nephroma") (Boggs and Kimmelstiel, 1956). The multilocular cyst is quite different from the simple renal cyst, and it should not be considered to be merely a simple cyst with septate divisions. Nor is the multilocular cyst related to polycystic renal disease. It has been reported in patients of all ages, many (about 50~) in children under five, in whom the clinical differentiation from Wilms's tumour is almost impossible. M E D U L L A R Y CYSTS There are diseases of the kidney manifested by cysts wholly or chiefly in its medulla. Involvement of the medulla may also occur as part of generalized cystic disease, such as in the polycystic kidney. The conditions with cysts primarily in the medulla have little in common except for the location of the cystic changes. In this group may be included: medullary sponge kidney, medullary cystic disease, the medullary form of renal papillary necrosis, and pyelogenic cysts. Unfortunately, some of these terms have been used interchangeably, the same name referring to different conditions. Strauss (1962) has emphasized a clinical and morphologic difference between medullary sponge kidney and medullary cystic disease, which seem to be separate entities.

MEDULLARY SPONGE KIDNEY.--Even though medullary sponge kidney is ordinarily a disease of adults, only occasional cases having been recognized in childhood, the condition is regarded as a developmental defect of the renal collecting ducts. The ducts are ectatic or cystic and are lined by cuboidal, columnar or transitional epithelium. The condition goes by many names, including: cystic disease of the renal pyramids, congenital cystic dilatation of the renal collecting tubules, cystic dilatation of the urinary pathways, multiple cysts of the renal medulla, and renal tubular ectasia. Although uncommon in the literature, this is not a rare disease (Lenarduzzi, 1939; Abeshouse and Abeshouse, 1960). Ekstrom et al. (1959), who reported a series of 44 cases, found no sex predilection, although other authors state a predominance of males (2'5:1). In the majority of reported cases the abnormality is bilateral (60-80~), although there are rare instances of localization of the condition to only one pyramid of one kidney. In some cases the cystic cavities are located mainly in the papillae; in others the involvement extends further into the pyramids. Most cases are discovered in the third to fifth decades of life, generally because of secondary complications. Clinically the disease is without symptoms unless complications ensue : recurrent pyelonephritis, gross or microscopic hematuria, and renal colic, findings related to either infection or stone formation. Calculi occur in 50 to 90 ~ of the reported cases and infection in about 40 ~. Abdominal films may show renal calcifications, consisting of multiple small calculi in the distribution o1 the pyramids; occasionally the calculi are larger in diameter than the usual few millimeters (Fig. 15). The kidney size shows no constant

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A FIG. 16 B Medullary sponge kidney. A 53-year-old female with recurrent episodes of pyelonephritis. Normal BUN. (A)--Intravenous urogram shows round and linear collections of opacified urine in many of the pyramids bilaterally with no disturbance of the configuration of the calyces. (B)--Retrograde pyelogram also demonstrates opacification of the dilated and cystic collecting ducts, although usually retrograde study does not show the abnormality as well as does urography.

change; it may be normal, small or enlarged. Urography demonstrates normal appearing calyces and pelvis, although calyceal cupping may be deeper than usual because of papillary hypertrophy. Dilated papillary ducts are visualized and measure up to several millimeters in diameter. These dilated Collecting ducts are more apt to be opacified on intravenous urography than at time of retrograde pyelography (Fig. 16). There is usually good excretion of the contrast medium. Because of superimposed infection with parenchymal involvement, there may be associated areas of cortical thinning due to the subsequent pyelonephritic scarring. The appearance of opacified large ducts in the papillae or pyramids, in clusters near the opacified calyces, has been likened to bouquets of flowers. It is sometimes difficult, however, to differentiate slight degrees of medullary sponge kidney from prominent normal ducts seen frequently during high-dose urography with the newer tri-iodo contrast media (Palubinskas, 1963). The x-ray findings remain stationary, except for renal changes occurring with the complications of infection or progressive formation of calculi in the cysts. The condition has been reported only rarely in childhood, and the problem of classification has been reviewed by Habib et al. (1965). The designation of cases showing cortical involvement as examples of medullary sponge kidney has been questioned. In this regard, medullary ectasia is sometimes a finding in childhood polycystic disease (Lathrop, 1959) and may be a significant observation on radiographic examination (Reilly and Neuhauser, 1960). The possibility must always be kept in mind, therefore, that some cases reported as medullary sponge kidney are actually examples of polycystic disease with marked medullary involve-

ment. Other congenital malformations have been described in association with this condition (Habib et al., 1965). A familial incidence has been reported only occasionally (Morris, Yamauchi, Palubinskas, and Howenstine, 1965). MEDULLARY CYSTIC DISEASE.--In cystic disease of the renal medulla there are numerous cysts with a honeycomb-like pattern in the medulla with few or no cysts in the cortex (Smith and Graham, 1945; Kerlan and Russell, 1963; Strauss, 1962). The cysts vary in diameter from pinpoint to a few centimeters and are lined by low, frequently atrophic epithelium. The kidneys are often small and scarred, and there is a variable degree of interstitial cortical and medullary fibrosis. The cortex is thin and poorly demarcated from the medulla, and there are glomerular hyalinization and tubular atrophy. In some cases, however, the kidneys are enlarged. There may be associated cysts of the liver or pancreas. This rare condition is associated with progressive renal failure. Patients often present with an insidious, obscure, chronic anemia (Cacchi and Ricci, 1949). Marked azotemia and inability to concentrate the urine have been found. Hypertension develops terminally. Other patients have presented with inability to conserve sodium, a salt-wasting syndrome clinically resembling Addison's disease, except that it is characterized by persistent azotemia and unresponsiveness to mineralocorticoid therapy (Thorn, Koepf, and Clinton, Jr.~ 1944). Routine urinalysis is deceptive, since proteinuria is minimal and formed elements are not present. The consequences of renal failure include hyperparathyroidism and osteitis fibrosa. In a stage of the disease before advanced renal failure, urography may show calyceal distortion

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FIG. 17 (Courtest of Dr. J. S. Dunbar.) Medullary cystic disease. Five-and-one-half-month old girl with progressive abdominal enlargement for several months. Smooth mass felt in each flank. UrinalYSiS negative, BUN elevated (20 mg. ~), anemia (Hgb 10-4). Intravenous urogram shows enlarged kidneys with pressure deformities of the pelvicalyceal systems. Bilateral nephrectomies (renal transplantation) at age twenty months showed medullary cystic disease with extm3sive fibrosis.

FIG. 19 Pyelogenic cyst. A 54-year-old female with several episodes of urinary tract infection. Intravenous urogram shows a large pyelogenic cyst at the medial aspect of the left kidney with a long, thin isthmus extending to an upper calyx.

F~G. 18 Medullary necrosis. A 58-year-old man with no urinary Complaints at present. Nephrotomogram shows a single collection of opacified urine in several of the renal pyramids close to the mid-portion of the calyceal cup.

due to pressure from the numerous cysts (Fig. 17). Usually, however, urography shows lack of excretion of contrast medium, most likely due to renal failure. There are no renal calcifications. The pathogenesis of this condition has remained obscure. The histologic appearance is strikingly different from that in medullary sponge kidney, and the pattern, as indicated by the early descriptions of this disease as a form of pyelonephritis, is suggestive of a chronic inflammatory process. An acquired, nonbacterial "interstitial" nephritis cannot be excluded, although recent data have suggested that the disease is genetically determined (Goldman, Walker, Merigan, Gardner, Jr., and Bull, 1966). Most of the reported patients have been young adults, with death occurring usually in the second to fourth decade. RENAL MEDULLARY NECROSlS.--This condition has also been known as renal papillary necrosis, necrotizing renal papillitis, and papiUitis necroticans renalis. Necrosis and destruction of the papilla or pyramid develop as the result of ischemia. The necrotic tissue is passed into the calyx, where it may

78

CLINICAL RADIOLOGY

A FIG. 20 B Pyelogenic cyst with calculi. A 49-year-old female with intermittent left flank pain. (A)--Scout film shows a collection of several calculi at the lower pole of the left kidney, the renal outline appearing normal. (B)--Intravenous urography demonstrates that the calculi lie within a pyelogenic cyst with a narrow isthmus extending to a lower calyx.~

FIG. 21 Inflammatory cyst. A 41-year-old female with two weeks of dysuria, frequency and fever. Urine was loaded with RBC and WBC. Intravenous urogram demonstrates a large irregular cavity in the right kidney. Nephrectomy showed this to be a large renal abscess communicating with the pelvicalyceal system.

remain and be encrusted with calcium or be passed into the lower urinary tract. Renal medullary necrosis has been reported in association with a number of other conditions, ineluding diabetes mellitus, chronic obstructive t~ropathy, ingestion of large amounts o f phenacetin, pyelonephritis, sickle cell disease, trauma, and prolonged hypotension (Lindvall, 1960; H a r r o w , Sloane, and Liebman, 1963). It is thus an acquired disease, occurring more commonly in the female (about 5:1); it is usually bilateral (85~) and is discovered most commonly after the fourth decade of life. According to the Gtinther classification (Gtinther, 1948) there are two forms of renal papillary necrosis, depending on the extent of initial involvement of the papilla or pyramid. In "papillary necrosis" the sequestration starts from the calyceal fornix so that there is loss of the entire calyceal "cupping". In "medullary necrosis" the sequestration develops centrally in the papilla, with maintenance of the calyceal fornices. W i t h extension of the necrotic tissue into the calyx, a "cyst" appears in the papilla and communicates with the calyx, usually in its central portion. It is this medullary form which

CYSTIC

DISEASES

OF

THE

79

KIDNEY

FI6. 22 Tuberculosis. A 38-year-old female with known renal tuberculosis. Intravenous urography shows destruction of upper calyces. There are several cystic areas in the lower pole representing parenchymal destruction and localized hydrocalycosis, due very likely to tuberculous stenosis of the inferior infundibulum.

FIG. 23A and B

Fxo. 22

A

Cyst with nephrolithiasis. A 48-year-old female with one year history of right renal calculus. (A)--Scout film shows a large oval calculus in t h e l o w e r p o r t i o n o f t h e r i g h t k i d n e y . (B)--Intravenous urography demonstrates that the calculus lies in a cystic cavity due to marked dilatation of a lower calyx and atrophy of the immediately surrounding renal parenchyma, related to repeated episodes of obstruction at the neck of the calyx.

FIG-23

B

80

CLINICAL

RADIOLOGY

A FIG. 24 Parapelvic cyst. A 70-year-old female with no specific urinary tract complaints. (A)---Nephrotomogram on the !eft shows a round soft-tissue mass impressing on the pelvis and deviating the upper ureter medially_ Note the crescentic radiolucent rim between the mass and the kidney. (B)--The nephrographic phase of the angiogram demonstrates that the mass is extrinsic to the kidney, causing compression deformity of the medial border of the kidney.

might be classified with cysts of the medulla (Fig. 18). Usually many pyramids are involved, although typically there is only one cavity per pyramid. The cavities may subsequently epithelialize. The course of the disease may be rapidly fatal because of renal failure or slowly progressive with recurrent acute episodes over a period of years. PYELOGENIC Cyst.--This condition, which has also been referred to as calyceal diverticulum and peripelvic cyst, is located close to a calyx, with which it communicates through a narrow isthmus. The cyst and isthmus are lined by transitional epithelium continuous with that of the calyx. The cyst is usually solitary and small, less than 1.5 centimeters in diameter. The connection with the calyx is usually near its fornix. The cyst fills during intravenous urography by overflow of the opacified urine from the pelvicalyceal system (Fig. 19). Hence the cyst opacifies more slowly than its adjacent calyx. There are usually no symptoms. However, due to the long narrow

isthmus the pyelogenic cyst may drain poorly, with l resultant urinary stasis favoring the occurrence of infection or the production of calculi. Hence, there may be symptoms of pyelonephritis, hematuria or renal colic. Calculi in the pyelogenic cyst may be of different types: single or several calculi that occupy most of the cyst (Fig. 20) or multiple minute calculi that "layer out" in the erect position. This lesion may be congenital and due to abnormal differentiation of the pelvicalyceal system from the metanephric duct, or it may be acquired following the rupture of a small cyst or abscess into the calyx. MISCELLANEOUS I N T R A R E N A L CYSTS Renal cysts of varying size may develop as secondary lesions in association with inflammatory (Fig. 21), neoplastic, and traumatic conditions. Cysts have been described in pyelonephritis, renal tuberculosis (Fig. 22) and nephrolithiasis (Fig. 23).

CYSTIC DISEASES OF THE KIDNEY

Echinococcus cysts usually arise in the cortex, frequently calcify and gradually enlarge, many eroding into a calyx to produce an "open" cyst (Surraco, 1939). Renal cell carcinomas often undergo cystic degeneration. As noted above, simple cysts of the cortex develop in older patients with nephrosclerosis. EXTRAPARENCHYMAL RENAL CYSTS PARAPELVIC CYSTS.--Parapelvic cysts do n o t

occur in the renal parenchyma, but are located in the hilum. They may be simple or multilocular, single or multiple, unilateral or bilateral. They are usually small, rarely larger than 5 cm., expansion being limited by the confines of the hilum. These cysts probably have origin in lymphatic ectasia, perhaps due to chronic inflammatory changes. It has also been suggested that they may be congenital and arise from embryonic rests, but they are rarely seen in childhood. The parapelvic cyst is radiographically distinctive : (Fig. 24) (1) located in or near the hilum, the cystic mass compresses the renal pelvis; (2) as distinct from parenchymal cysts (simple or multilocular), the parapelvic cyst is not surrounded by opacified renal parenchyma during urography; (3) calcification is extremely rarely, if ever seen; (4) the cyst, originating in tissues of the hilum, is frequently surrounded by fat, which on urography or sometimes on a plain film is demonstrable as a crescentic radiolucent shadow about the hilar or perihilar mass (Shapiro, 1963); (5) the cyst may cause obstruction at the pelvis and subsequent hydronephrosis; and (6) the cyst does not communicate with the pelvis. PERINEPHRIC CYSTS.--Perinephric cysts are rare lesions consisting of encysted collections of fluid that more or less surround the kidney. They are also known as pararenal pseudocyst, hydrocele renalis, perirenal hydronephrosis, perirenal effusions, hygroma perirenalis, and pararenal pseudo hydronephrosis. These cysts lie under or within the capsule, or they may be collections of fluid between the capsule and perirenal fat. The walls are fibrous and generally do not have epithelial linings. They are believed to result principally from extravasation of urine secondary either to trauma or to urinary obstruction. Some effusions may result from replacement of perinephric hematomas by serous fluid. The cyst may surround the entire kidney, although it more commonly lies alongside and only partially encompasses the kidney. Perinephric cysts are relatively uncommon in childhood, although they are seen in young infants suffering from congenital lower urinary tract G

81

obstruction (e.g., posterior urethral valves) (Rattner, Meyer, and Bernstein, 1963). The cysts may compress the kidney, the pelvis, and eventually the ureter, leading to progressive hydronephrosis. Patients complain of abdominal pain, and a mass may be palpable. The urographic findings depend on the size and location of the cyst and on the presence or absence of hydronephrosis. With marked hydronephrosis there may be no excretion of contrast medium, and the retrograde pyelogram may show complete obstruction at the uretero-pelvic junction. The cyst may cause displacement of the kidney and calcification is occasionally seen in the wall of the cyst. This work was supported by United States Public Health Service Research Grant N.I.H. 5MOIFR - 66 - OG51 RISI, and the Health Research Council of the City of New York Research Contract No. 1243. REFERENCES AEESHOUSE,B. A_ & ABESHOUSE,G. A. (1960). J. UroL, 84, 252. AREV, J. B. (1959). aT. Pediat., 54, 429. BA~GENSTOSS,A. H. (1951). Med. Clin. N. Amer., 35, 987. BARTMAN, J. & BARRACLOUGH,G. (1965). J. Path. Bact., 89, 233. BAXTER, T_ J. (1965). Nephron, 2, 15. BERNSTEIN, J. • MEYER, R. (1967). In Brennemann-Kelley Practice of Pediatrics Vol. III, Chapter 26. Maryland: Harper & Row. BIALESTOCK,D. (1960). Austral. Ann. Med., 9, 53. BOGGS, L. K. & KIMMELSTIEL_P. (1956). J. Urol., 76, 530. CACCHI, K. & RlCCI, V. (1949). d. Urol. Med.-Chir., 55, 497. DALGAARD,O. Z. (1957). Acta Med. Scandinav. (Suppl. 328). DEWEERD, J. H. ~9, SIMON, H. B. (1956). J. Urol., 75, 912. EKSTROM,T., ENGFELDT,B., LAGERGREN,C. & LINDVALL,N. (1959). Medullary Sponge Kidney. Stockholm: Almqvist & WikselL ENGSTROM, N., LJUNGQVIST,A., PERSSON,B. & WETTERFORS, J. (1962). Pediatrics, 30, 681. ERICSSON, N. O. & IVEMARK,B. I. (1958). Arch. Path., 66, 255. FINE, M. G. & BURNS, E. (1959). J. Urol., 81, 42. GLASER, S. (1952). Brit. J. Surg., 40, 74. GOLDMAN, S. H., WALKER, S. R., MERIGAN, T. C., Jr., GARDNER, J. D., Jr. & BULL, J. M. C. (1966). New Engl. J. Med., 274, 984. G/3NTHER, G. W. (1948)_ Z. Urol., 41, 310. HABIB, R., MOUZET MAZZA, M. T., COURTECUISSE,V. & ROYER, P. (1965). Ann. Pediat. (Paris), 12, 288. HARROW, B. R., SLOANE, J. A. & LIEBMAN, N. C. (1963). New Engl. J_ Med., 268, 969. KERLAN, M. & RUSSELL,O. Q. (1963). d. Tenn. Med. Assoc., 56, 330. KERR, D. N. S., WARRICK, C. K. & HART-MERcER, J. (1962). Clinical Radiology, I3, 85. LATHROV,D. B_ (1959). Pediatrics, 24, 215. LENARDUZZI, G. (1939). Radiol. Med., 26, 346. LINDVALL, N_ (1960). Acta Radiol. (Suppl. 192). LJUNGQVIST,A. (1965), Acta Path. Microbiol. Scandinav., 64, 309. LUNDIN, P. M. & OLOW, I. (1961). Acta Paediat., 50, 185,

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MORRIS, R. C., YAMAUCHI, H., PALUmNSKAS, A. J. & HOWENSTINE, J. (1965). Amer. J. Med., 38, 883. OSATHANONDH, V. • POTTER, E. L. (1964). Arch. Path., 77, 459. PALUBINSKAS, A. J_ (1963). Radiology, 81, 963. PARKKULAINEN, K. V., HJELT, L. & SIROLA, K. (1959). Acta Chir. Scandinav. (Suppl. 244). PASTERNACK, A. (1960). Ann. Paediat. Fenn. (Suppl. 14). PA'rHAr¢, I. G. & WILLIAMS, D. I. (1963). Brit. J. Urol., 36, 318. POWELL, T_, SHACKMAN, R. & JOHNSON, H. D. (1951). Brit. J. Urol., 23, 142. RATTNER, W. H., MEYER, R. & BERNSTEIN, J. (1963). J. Pediat., 63, 84. REILLY, B. J. t~ NEUHAUSER, E. B. D. (1960). Amer. J. Roentgenol., 84, 546.

RUBENSrEIN, M., MEYER, R. & BERNSIEtN, J. (1961). g Pediat., 58, 356. SCHWARTZ,J. (1936). J. Urol., 35, 259. SHAPIRO, R. (1963). Amer. J. Roentgenol., 90, 81. SMITH, C. H. & GRAHAM, J. B. (1945). Amer. J. Dis. Child.. 69, 369. SPENCE, H. M. (1955). J. Urol., 74, 693. STRAUSS,M. B. (1962). Ann. Int. Med., 57, 373. SURRACO,L. A. (1939). Am. J. Surg., 44, 581. THORN, G_, KOEPF, G. F. & CLINTON, M., Jr. (1944). Ne~ Engl. J. Med., 231, 76. UBELHOR, R. (1933). Z. Urol., 27, 79. VELLIOS, F. & GARnETT, R. A. (1961). Amer. J. Clin. Path., 35, 244_ VOTrI, D. (1961). Zbl. Allg. Path., 102, 554.

BOOK REVIEWS Urologic Roen lgenalogy.

By MARCY L. SUSSMAN, GEORGE JACOnSON and E. HOWARD JAYNE. Pp. 302, with ilhistrations. Baltimore: Williams & Wilkins Company, 1967. 817.

'Urologic Roentgenology' by Drs. Sussman, Jacobson and Jayne is a separate printing of Chapter VII1 of Ross Golden's 'Diagnostic Roentgenology', and was initially published in 1936. The considerable advances in the subject since then have necessitated a virtually rewritten text for this edition, and a replacement of most of the ilhistrations. Any text-book is bound by the inevitable time interval involved to be out of date at least in part before it gets to the reader. However, these three authors, working in Los Angeles and Phoenix, Arizona, have done well to present modern thoughts and trends in the radiology of the renal tract, despite their admission that references to the literature more recent than 1965 had to be omitted. The book is orthodox in its contents and format. The illustrations are profuse and of good quality. The style is straightforward easy to read, and avoids the verbosity of some American writing. The reader is presented with a comprehensive and detailed account with supporting bibliography of the radiology of the entire urinary tract both from the point of view of method and results. The topics covered inchide a discussion of tile merits and properties of the various contrast media available, the techniques of intravenous urography including infusion urography together with nephrotomography, renal angiography by all routes, and the use and value of renal scans by isotopic techniques. In addition there is a full conventional description of the anatomical, pathological and functional changes which may occur in the renal tract. Quality .varies a.Jittle fi'om section to section. For example a good section deals with the difficult problem of the significance of the radiological and renal scan findings in a suspected case of renal hypertension. However readers in this country will probably f i n d the sections dealing with chronic pyelonephritis and obstructive uropathy not quite up to the standard of the rest of the book, and little is mentioned by way of renal 'philosophy', how to approach a renal problem, and how to analyse the facts available. Nevertheless this is a sound textbook and book of reference and should be widely accepted by trainee and experienced radiologist alike. J. D. CRAVEN

Normal Radiological Anatomy. Radiological Optics and Film Interpretation. By HENRY TILLIER. Translated from the second French edition and edited by Ronan O'Rahilly. Pp. 382, with 375 illustrations. Springfield, Illinois: Charles C. Thomas, 1968. $12.50. A radiographic image is, of course, very different from a simple photograph. Failure to appreciate this trite observa, tion often causes difficulty in understanding the shadows cast by complex structures. This work does much to clarify many puzzling morphological features that are so often seen in radiological practice. Principles of radiological optics are clearly expounded and their application to the study of radiographic images are explained. Though all parts of the body are studied, the emphasis of this book is on the skeletal system. The translator has succeeded in making the text clear and concise. Dr. O'Rahilly has spared no effort to make it understandable to the English-speaking reader. He even gives us a phonetic pronunciation of Dr. Tillier's name; perhaps modesty prevented his giving us one of his own name! Despite the excellent translation, the very nature of the material makes the work rather heavy going in places. One would regard the volume as a supplement to, rather than a replacement of, the standard works on radiological anatomy. I regard it as a very useful aide when one is confronted with a radiological image that one feels to be of no significance yet, nevertheless, is uncertain of its precise nature. PHILIP JACOBS

Thermoluminescent Dosimetry.

By J. R. CAMERON, G. N. KENNEY and N. SUNTHARALINGHAM. University of Wisconsin Press Ltd., 1968. 71s. 3d.

As would be expected from these three authors, the originators of T.L.D., the subject is covered well at an elementary level. Much of the work was carried out at the University of Wisconsin and published in their annual reports. More detail could have been included here; none of the topics is discussed comprehensively. Instead, the type is large and the margins are wide. However, as an introduction to T.L.D., a good book to start with and for the researcher, an excellent bibliography. C. A. JOSLIN