T U M O U R S O F T H E K I D N E Y x47

T U M O U R S O F T H E K I D N E Y * BY ALAN STEWART JOHNSTONE, M.D., F.R.C.S., F.F.R.

PROFESSOR O] ~ RADIODIAGNOSIS, UNIVERSITY OF LEEDS

AFTER reviewing most of the recent radiological literature on renal tnmours one is forced to the conclusion that little has been added to our knowledge in the last decade. Some qualification of this statement, however, is required with regard to renal arteriography, for in several countries this method of diagnosis has made considerable progress. Here it is still untried and without personal experience I cannot do more than refer to the procedure.

At a meeting held in the Royal Society of Medicine in 1938 , Rohan Williams dealt so fully with the radiology of renal tumours that it seems unnecessary to do more than review his paper and bring out a few controversial points.

I t will be appreciated that the radiologist must interpret the term ' tumour of the k idney ' in its widest sense and include cysts, for they are of much greater importance than the simple tumours. This contention may not meet the approval of the pathologist who commonly finds adenomata, fibromata, and lipomata at autopsy, but these are of no clinical significance. The only simple tumour that need be mentioned is the solitary adenoma which may grow to a large size and deform the pyelogram in a manner indistinguishable from carcinoma. But the pathologist also may have the greatest difficulty in differentiating between these two tumours, and so it is obvious that there is no justification for the radiologist attempting to make such a diagnosis (Fig. 125).

Certain criteria have been laid down on which to base the diagnosis of a renal tumour. I t is customary to divide these signs into two groups-- those which are evident on the plain film, and those which are found by pyelography.

GROUP I. PLAIN FILM I. Deformity of the renal outline. 2. Enlargement of the renal outline. 3- Displacement of the renal outline. 4. Calcification.

I t is perhaps relevant at this stage to mention the methods of increasing the definition of the renal shadow. The simplest and safest is found in excretion pyelography. There does not appear to be any justification in producing a temporary obstruction of the ureter by instrumental means in order to improve the renal definition. Weems and Florence (1947) claim that by this method variations in the cortical density may indicate both the presence and extent of a tumour. I have not seen any examples of this work, but feel that such deductions must be hazardous. Perirenal insufflation provides the best method of outlining the kidney but its use in these cases is not warranted.

I, D e f o r m i t y o f the Rena l O u t l i n e . - - T h e normal renal outline is a smooth convexity, but occasionally f~etal lobulation persists, giving a nodular appearance. I f one nodule only exists, then it must be regarded with suspicion because it might be produced by tumour, cyst, or infection.

2. E n l a r g e m e n t . - - A malignant tumour does not enlarge the renal outline in a uniform manner such as occurs in hydronephrosis. Instead, the growth usually takes place irregularly at one or other pole. The borders of the tumour may or may not be clearly defined, a feature which depends to some extent on the type of tumour and the rate of growth ; for example, some slow- growing malignant tumours are well encapsulated, others may arise in cysts and possess clear-cut,

* Being the substance of a lecture delivered to a joint meeting of the Faculty of Radiologists and the Section of Radiology of the Royal Society of Medicine at the Royal College of Surgeons on March 19, 1949.

I48 J O U R N A L O F T H E F A C U L T Y O F R A D I O L O G I S T S

rounded margins thus simulating non-malignant tumours. On the other hand carbuncle, actino- mycosis, and tuberculoma may give rise to irregular enlargement with indefinite margins. It needs no further comment to illustrate what little diagnostic help can be obtained from enlargement alone. One is tempted, however, in the presence of a clearly defined globular shadow at the lower pole of the kidney, to suspect a cyst.

The kidney may enlarge to such an extent that it produces a uniform opacity which, pushing aside the bowel, occupies a large part of the abdomen. This is not pathognomonic of tumour alone,

Fig. iz5.--Adenoma or adenocarcinoma. Large tumour mass which had been observed over four years without appreciable pyelographic change. Elongation, dilatation, and some obliteration of calices.

Fig. I a6.--Carcinoma. Renal outline normal. Retro- grade pyelography showed some obliteration of the lowest calices, but the growth had spread widely in the parenchyma.

for other conditions, such as perinephric abscess, hydro- and pyo-nephrosis, neoplasms of the renal capsule, retroperitoneal neoplasms, and pancreatic cysts have to be considered. Two small diagnostic points may be mentioned--lordosis is rarely seen in cases of tumour, whereas it forms one of the features of perinephric abscess, and cystic swellings, like hydronephrosis, do not obliterate the psoas line.

It should be remembered that while the abnormal shadow gives a fair indication of the size of the tumour, it does not follow that in a kidney of normal size a tumour must be very small, because widespread infiltration of renal tissue may occur without appreciable change in the outline (Fig. 126).

T U M O U R S O F T H E K I D N E Y 149

3" D i s p l a c e m e n t o f the Rena l Ou t l i ne . - -The re is an old surgical adage that a renal tumour does not cross the midline. Exceptions do arise : for example, when a tumour develops in a horse- shoe or ectopic kidney. Some embryonal tumours may also extend to the opposite side. Mintz (i938) pointed out that renal tumours may displace the renal pelvis in many directions--upwards, downwards, laterally, and medially, but never downwards and medially together. A recent article by Greene (i948) draws attention to extensive displacements of the kidney brought about by extrarenal simple tumours. The author concluded that if a kidney was far removed from its normal position and yet retained satisfactory function, then there was a strong possibility that the turnout displacing it was simple and extrarenal. He pointed out that malignant extrarenal tumours

Fig. iz7.--Di@lacement of left kidney across the midline by pancreatic cyst. The opaque catheter has reaehed the renal pelvis. The left psoas line is clearly seen.

Fig, I z8.--Carcinoma--right kidney. Rounded soft- tissue swelling at lower pole with central filigree calcifica- tion. Obliteration of lowest ealiees. Invasion of pelvis with filling defects. Distortion and dilatation of central ealices.

tended to invade and fix the kidney rather than displace it widely. With this hypothesis in mind I reviewed several cases in which there was marked displacement. Only one case, however, was found to approach this category, The patient was a woman of 35 with a large cystic swelling in the left upper abdomen. On excretion pyelography the kidney was non-functioning and a provisional diagnosis of hydronephrosis was made. An opaque catheter, however, revealed that the renal pelvis lay across the midline apparently displaced downwards and medially. The retrograde pyelogram was not satisfactory owing to a technical fault so it cannot be stated that the pelvis was normal (Fig. 127). The tumour was explored and found to be a large pancreatic cyst. I t was concluded (but not proved, so that an anomaly cannot be dismissed) that the kidney had been displaced across the midline. No explanation was offered for the loss of function and this case

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cannot be placed in quite the same category as those of Greene. There is, nevertheless, some support for his hypothesis.

Two cases showed a normal renal pelvis grossly displaced by a large tumour, subsequently proved to be of renal origin. In neither casewas the midline crossed, for the displacement was downwards and laterally.

Lastly, in a case of an enormous retroperitoneal sarcoma which extensively involved both kidney and spleen, pyelography showed that the kidney, still functioning, lay in its normal position as if fixed in a mould.

Summary.--There appears to be some support both for Mintz's observations, that renal tumours do not displace the renal pelvis downwards and medially together, and for Greene's

Fig. I29.--Hydatid disease. I r regular deposits of calcifica- tion in left renal area tumour, obliteration of lower calices and pelvis, secondary dilatation of upper calices.

Fig. I3o.--Simple cyst. Calcification in wail. Sub- capsular type of cyst causing no defect in pyelogram.

hypothesis that a tumour which displaces a normal functioning kidney over the midline is probably simple and extrarenal in origin.

4, Calc i f i ca t ion . - -This is not a common feature. In the 3 ° cases reviewed for this paper it occurred twice. Graham (i947) found calcification in only 2 per cent of I95 cases. Austen (I943) found I6 instances in 98 cases, yet Kerr and Gillies (i944) found it in a third of their cases.

Calcification is said to be due to avascular necrosis affecting some part of the tumour. It may be central or eccentric and does not represent in any way the size of the tumour. Usually it is relatively small and localized, but widespread distribution has been recorded. It is difficult to describe the calcification, because it does not conform to any constant pattern. I t is generally ill-defined and patchy with small nodular deposits, but in one case it formed a filigree pattern (Fig. I28). The prognosis in cases which exhibit calcification is said to be worse than that in

T U M O U R S O F T H E K I D N E Y i5i

non-calcified tumours. In the differential diagnosis, calcification occurring in other conditions, such as hydatid disease, simple cysts, tuberculosis, and ealcinosis must be considered (Figs. Iz9, I3o).

Sumrnary.--Calcification is of real diagnostic value, but is rarely present.

G R O U P II. P Y E L O G R A P H Y

There has been much discussion as to the relative value of the excretion and the retrograde pyelography. It is rather a waste of time to pursue this subject, for excretion pyelography has now become a routine procedure in the preliminary investigation of urological cases. There is

Fig. I3r.--Carcinoma--right kidney. Sucking out and dilatation of lowest minor calix. Compression of major calix. Displacement of ureter and renal pelvis.

Fig. i3z.--Carbuncle. In this case the upper major ealix appears elongated, but the minor calices of the middle group show more displacement and flattening than expected in a tumour. The clinical picture, however, was typical of carbuncle.

no doubt that in almost all cases the excretion pyelogram will give some indication of an abnor- mality, but so often it leaves an element of uncertainty because the filling appears to be inadequate. It is perhaps unnecessfiry to add that abdominal compression must not be used in cases of a tumour, which mitigates against obtaining a good pyelogram. Retrograde pyelography can remedy this defect and give a better appreciation of the abnormalities. I t should be mentioned, however, that the retrograde method' may produce a shadow so dense that it obscures a small filling defect such as might be produced by a papilloma of the renal pelvis. ,

Sufficient use of lateral films is perhaps not made in the diagnosis of renal turnouts. It is reasonable to assume that in some cases the earliest displacements will be found in an anteroposterior direction and the full appreciation of them may be lost when the examination is confined to the supine position.

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The principal radiographic features are : - - i. Obliteration, partial or complete, of the calices. 2. Elongation of calices, with either compression or dilatation. 3. Displacement of calices. 4. Secondary dilatation of calices. 5. Obliteration, partial or complete, of the pelvis. 6. Dilatation of the pelvis. 7. Displacement of the pelvis and upper third of the ureter. 8. Non-filling of calices and pelvis. I . Obl i t e ra t ion , or amputation, of one or more calices is the commonest pyelographic feature.

It may be partial or complete, and results from destruction of the calices or blocking of the lumen by growth or clot.

2. E l o n g a t i o n of calices with tapering or compression is the most characteristic feature of a neoplasm. The calix, perhaps a little dilated, appears to have been drawn away from the pelvis and the infundibular portion is tapered and appears compressed. To find an adequate explanatio n for these changes is not easy, but perhaps the most reasonable suggestion is that as the tumour grows it draws the calices away from the pelvis (Fig. i3i ). Wesson (1946), however, shows a speci- men in which recanalized thrombosed veins, running parallel to the calix, were considered to be the cause of the narrowing and elongation. Sometimes the whole of the calix is dilated as well as elongated, but this appearance may depend on the axial relationship of the X-ray beam to the maximum diameter.

3. Displacement of Cal ices . - -Whi le displacement occurs with malignant tumours, it is rare to find it alone. This feature is made into a separate entity in order to bring in a simple cyst, and, at the same time, mention the carbuncle. A subcapsular cyst may cause little or no ab .normality, but when the cyst or carbuncle develops at the expense of renal tissue, displacement and crowding of the calices takes place. (Fig. i32. ) These lesions show little tendency to obliterate calices, a point which serves to distinguish them from carcinomata.

4. Secondary Dilatation of Calices.--As mentioned earlier, dilatation may be associated with elongation, but more often it is found in calices unaffected directly by the tumour. In such cases, dilatation results from obstruction at a lower level brought about by growth or clot. I t is said, however, that dilatation is more frequently observed when the tumour is cystic, rather than solid. If this observation is correct, then the presence of several calices, dilated and elongated, must suggest cystic disease rather than tumour.

5. Obliteration, Partial or Complete~ of the Pelv i s .~Al though such abnormalities are inseparably associated with tumours of the renal pelvis they are found in a very high proportion of parenchymal tumours, for extension of growth into the pelvis is a common occurrence. (Fig. 133. ) Alternatively, clot or non-opaque calculus may be the cause.

6. Dilatation of the Pelv i s . - -Th i s is not a common finding, but may be due to obstruction of the ureter from causes previously mentioned. In some cases external pressure or kinking by tumour or glands may be held responsible.

7. Displacement of the Pelvis and Upper Third of Ureter . - -Reference to Mintz's obser- vations has already been made. Tumours of the lower pole, however, produce a very characteristic upward and medial displacement of the pelvis and the upper third of the ureter, which sweeps over the mass with a convexity towards the midline (Fig. 131 ). Although this feature may appear significant, it can occur with cyst, carbuncle, or abscess, and is not a diagnostic feature of tumour.

8. Non-filling o f P e l v i s . - - T h e function of a kidney may be completely suppressed, even when the tumour is small, if thrombosis of the renal vein occurs at an early stage. It can be readily appreciated that function will cease when the tumour destroys sufficient renal tissue or blocks the

T U M O U R S O F T H E K I D N E Y ~53

renal pelvis, either by growth or clot. Non-function, however, is not peculiar to tumour, as it occurs in hydro- or pyo-nephrosis. /What is significant, however, is the failure to fill the pelvis by the retrograde method. A tumour filling the pelvis may obstruct the catheter and opaque medium so that a pyelogram is prechided.

Professor Willis, in his admirabIe paper, has made it abundantly clear that it is useless to attempt differentiation of these tumours into separate categories. I have been impressed, however, after reviewing a number of pyelograms, by the frequent appearance of a picture which stands out as something quite different from the usual deformities. In Fig. I2 5 the tumour mass is clearly defined, and the visible ealices are distorted, elongated and a little dilated. Clinically, the turnour may have been in existence for a number of years, and no frank h~ematuria has been evident.

Fig. I33.--Carcinoma invading renal pelvis, producing a titling defect. Obstruction of upper group of ealiees with secondary dilatation. Displacement and partial obliteration of minor calix of lower pole. Probable complete obliteration of middle group of calices.

Fig. 1'34.--Carcinoma--renal pelvis. Extensive filling defect in dilated pelvis with caliectasis.

It would appear that these tumours are very slow growing and, in the early stages, may be adenomata. I have read with much interest a paper by Melicow (I944) who reviewed t96 cases at the Bentley Squire Clinic. Melicow has endeavoured to classify the tumours into clear- and granular-celled types. The clear-celled tumour arises from the tubules and may remain encapsulated for a considerable time. Eventually ischzemia, necrosis, heemorrhage, and calcification occur and a more disorderly growth of papillomata takes place ; the capsule ruptures and there is a rapid spread with early fatality. These tumours may arise from adenomata, and they may produce the radiologieal picture which has just been described.

The granular-celled carcinomata arising from the glomeruli and Bowman's capsules, on the other hand, are not encapsulated and spread more rapidly and more diffusely through the kidney, thereby causing greater obliteration of calices and pelvis (Fig. x35 ).

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TU/ViOURS OF THE RENAL PELVIS Tumours of the renal pelvis are much less common than those of the parenchyma, the figures

varying from io to 15 per cent of all renal tumours. Small papillomata may be obscured in the retrograde pyelogram if the concentration of the medium is too dense. Hmmangiomata, a rare cause of bleeding, are almost impossible to diagnose radiologically.

A pyelogram which is said to be pathognomonic has been described. The picture is one of a peculiar network in a small cavity which communicates with a calix. Such an appearance is produced by the medium percolating into the interstices of an angiomatous mass.

Fig. i35.--Carcinoma. Granular-celled type. Clot is seen forming worm-like filling defect i t /upper calix.

Fig. x36.--Wilras' tumour in child. Extensive invasion of left kidney. Tumour mass also present in upper pole of right kidney.

Carcinoma of the renal pelvis will produce irregular filling defects in the pyelogram. In addition, obstructive signs may be evident in varying degrees of dilatation of pelvis and calices (Fig. 134 ). The papilliferous type of tumour may extend widely into the calices and down the ureter to the bladder, so that both ureterogram and cystogram may show multiple filling defects.

In the differential diagnosis, blood-clot and calculi have to be considered. A filling defect produced by clot changes rapidly in appearance, which should be evident if the pyelogram is repeated within a few days. The clot, having shrunk, is no longer in such intimate contact with the smooth wall of the pelvis and calices. The opaque medium is thus able to flow round it and demonstrates the smooth outline of the walls separated by a worm-like filling defect (Fig. i35 ).

The non-opaque calculus will produce a constant filling defect which is smoother and rounder than a tumour. When opaque calculi are present the possibility of the coexistence of a carcinoma must be considered, for it is believed that in some cases the chronic irritation of calculi may give rise to malignancy.

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Finally, tumours of the pelvis may produce complete obstruction so that it is impossible to obtain a pyelogram by either method. This complete obstruction to the retrograde injection is strongly in favour of tumour.

TERATOMATA Teratomata are generally found in young children but occasionally in adults. In children,

particularly, the tumour is the presenting feature rather than the renal hmmorrhage. Retrograde pyelography in infants may be unsuccessful and excretion pyelography is often unsatisfactory because it seems impossible to free the abdomen from gas shadows. On three occasions I have seen a con- genital hydronephrosis mistaken for a Wilms' tumour. In each case the retrograde examination was impracticable and the diagnosis was based on a turnout and a non-functioning kidney. The lack of response to radiation therapy, however, pro- vided a pointer to the correct diagnosis. The Wilms' tumour is sometimes found bilaterally as illustrated in Fig. 136.

TUMOURS ASSOCIATED WITH HYPERTENSION

In several cases of hypertension the discovery and removal of renal cysts have resulted in cure or marked alleviation of the condition. Although the Goldblatt kidney is generally associated with some lesion which alters the renal blood-supply, and cysts are not usually considered to fall into this category, it becomes increasingly important to examine with the greatest care the pyelographic films which are done routinely before the Smithwick operation. We have had occasional surprises when kidneys which showed very little pyelographic abnormality were found at operation to be widely affected by cystic disease. It is also important to remember that carcinomata may arise in polycystic kidneys. This combination will present a very difficult, if not insoluble, diagnostic problem. Yet another complication is sometimes found when a cyst ruptures into the pelvis and causes profuse h~ematuria. The pyelogram may reveal, in addition to the characteristic changes of polycystic disease, a cavity in which the medium may show filling defects (Fig. 137 ) .

Fig. I 37.--Congenital cystic kidney. T w o cystic cavit ies have filled wi th m e d i u m . M a r k e d hmrnaturia . Defec t s in cavities due to clot.

RENAL ARTERIOGRAPHY It will be readily appreciated that the appearances in parenchymal tumours may be so varied that

pyelography does not provide a truly classical picture. Will renal arteriography provide the answer ? This method of examination, originated by Dos Santos (i929) , may ultimately provide the ideal diagnostic procedure, if and when it can be done without risk. According to Billings and Lindgren (1944) a parenchymal tumour may be recognized by the distortion of blood-vessels and the relative absence of filling in some area of renal tissue. New blood-vessels, growing in turnouts, may travel in any direction and be of the same calibre, thus becoming distinct from the normal arrangement. The opaque medium may also pass more rapidly into veins, indicating an abnormal communication. It is perhaps not generally realized that hypernephromata may occur in both kidneys, either as

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independen t growths or as secondary deposits. In such cases ar ter iography m a y prove its value. One cannot, however, escape f rom the fact that the p r imary t u m o u r may be so small as to defy even microscopic recogni t ion. Radiology, wi th all its technical variations, cannot therefore provide a posi t ive answer in every case.

BIBLIOGRAPHY AUSTEN, G. (1943), Amer. `7. Roentgenol., 49, 580. BILLINGS, L., and LINDGREN, O. (I944), Acta. Radiol. Stockh., 25, 625. GRAHAM, A. P. (I947) , `7. Urol., 58, IO. GREENE, L. F. (I948), Ibid., 59, 174. HARVEY, N. A. (I947), Ibid., 58, 669. KERR, H. DABNEY, and GILLIES, CARL L. (I944) , The Urinary Tract. Chicago : The Year Book Publishers. MELICOW, M. M. (I944), Ibid., 5 I, 333- MINTZ, E. R. (I938), `7. Urol., 39, 244. NACHMAN, M. (I944), Ibid., 51, 395. NELSON, O. A. (I945) , Ibid., 53, 521. SANTOS, R. Dos, and others (1929) , Med. Contemp. (Lisbon), 47, 93- WANG, S. L., and FLAQUE, A. V. (1944), `7. Urol., 51, 275. WEEMS, H. S., and FLORENCE, T. J. (1947), Amer..7. Roentgenol., 57, 338. WESSON, M. B. (1946), Urologic Roentgenology. London: Kimpton. WILLIAMS, E. ROHAN (1936), Brit. `7. Radiol., 9, 59.