A systematized approach to the differential diagnosis of renal masses

A comparison of radiologic methods in the diagnosis of renal mass lesions

The reliability of radiologic diagnosis was studied in 99 patients undergoing ultrasonography, computerized tomography and angiography in work up of renal mass lesions. The diagnoses were confirmed by angiography combined with percutaneous puncture or by surgery. Of the lesions, 37 were simple renal cysts and 56 were renal cell carcinomas. Eighty-eight percent were diagnosed correctly by ultrasonography, 96% by computerized tomography and 84% by angiography. The conclusion is that the radiologic evaluation of a renal mass lesion found at urography should start with ultrasonography. Percutaneous puncture is not recommended if all criteria of a simple renal cyst are strictly fulfilled at ultrasonography. In all other cases a computerized tomography is thought to be mandatory to avoid false negative diagnoses of malignant tumours or other diseases which may need therapy. In some patients a combination with angiography and percutaneous puncture is advised to establish a diagnosis prior to surgery.

Renal mass imaging: the internist's role

The busy internist will encounter numerous renal masses when ordering nonurologic imaging. Concise and quick delineation of cystic from solid masses is necessary. Cystic masses constitute the majority of these masses and once their nature is diagnosed, they require no further work-up or referral. Often, a single imaging technique is unable to confidently establish the cystic nature of a renal mass. Proper selection of an additional imaging modality will often be successful in establishing the cystic characteristics of a benign mass. Referral to a urologist is not necessary in this setting, since the internist can coordinate the imaging evaluation with proper radiologic consultation. Alternatively, when a mass is determined to be solid, urologic consultation and surgical evaluation are necessary. Minimization of the imaging sequence and hospitalization are critical in the diagnostic-related group era. Aimless wandering in the quagmire of imaging techniques is very expensive and nonproductive. Proper selection of one or two imaging tools and occasionally needle puncture should produce clarification of the cystic or solid nature of renal mass. On the basis of our experience, we have designed an imaging algorithm that provides a simple and concise approach to the diagnosis of a renal mass. It differs in design from that previously suggested by us and others because of decreased emphasis on nuclear medicine and greater emphasis on computed tomography. The more pivotal position assumed by computed tomography is based on improved scanner design and several large series attesting to the accuracy and cost-effectiveness of this imaging technique. It behooves internists to appreciate the role of various imaging tools in evaluating a renal mass. With radiologic consultation, internists should strive to confidently establish the cystic nature of a renal mass and to refer to a urologist solid masses or those whose nature remains persistently equivocal.

Echo-free renal masses on ultrasound: the stethoscope as an adjunct to their diagnosis

A patient with an intrarenal arteriovenous malformation is described. Ultrasound suggested this to be a renal cyst but auscultation revealed a loud bruit and, on the basis of this, arteriography rather than cyst puncture was carried out.

Pursuit of the renal mass. Is ultrasound enough?

The accuracy of ultrasonography in evaluating renal masses was assessed retrospectively in 260 renal lesions detected by intravenous urography in 242 patients. The ultrasonographic diagnosis was confirmed by cyst puncture, surgery, or autopsy. Of the lesions, 168 were benign cysts, and all were diagnosed correctly by ultrasonography. The remaining 92 lesions were renal carcinomas, and 90 were diagnosed correctly by ultrasonography. In retrospect, it was clear that the two missed cancers did not fulfill all the ultrasonographic criteria for a cyst. An algorithm is presented for the differential diagnosis of renal masses primarily by ultrasonography, and the arguments in favor of operative diagnosis of renal masses are rebutted. With the approach described, invasive studies such as cyst puncture and arteriography will be required for a definitive diagnosis in fewer than 10 percent of patients, and the morbidity and expense of the diagnostic approach will be minimized, with no decrease in accuracy.

An infected renal cyst

A patient with a large renal cyst that became infected, after puncture, is reported. A very high LDH of the aspirate was highly suggestive of infection. CT showed air bubbles, a thick wall with little contrast enhancement, and low density content. CT alone cannot differentiate an infected cyst from an abscess necrotic tumor.

Coronal renal ultrasound: I

With recent advances in ultrasound technology, concomitant improvement in sonographic techniques have been required. Sonographic scanning in coronal orientation, both in transverse but especially in longitudinal direction, has demonstrated a number of advantages over the routine transverse and sagittal scans. Closer correlation with functional anatomy of the kidney, more comprehensive scanning with less inerference from adjacent tissues, and better understanding by the clinician are the most obvious advantages of the coronal approach.

Carcinoma in a renal cyst: computed tomography diagnosis

We report a case of carcinoma in a renal cyst diagnosed by computed tomography. Ultrasound was unavailable because of scheduling difficulties and computed tomography provided a useful alternative in identifying the cystic and solid features of the mass. There was a good correlation of the computed tomography scan with pathology except for a small tumor nodule at the base of the cyst, which was not seen on the scan.

Comparison of computed tomography and ultrasound in abdominal staging of renal cancer

The relative accuracy of computed tomography (CT) and ultrasound in abdominal staging of renal cancer was determined in 22 patients. CT is capable of detecting tumor invasion of perinephric fat and adjacent muscles, which cannot usually be shown by ultrasound. While both CT and ultrasound demonstrate venous and retroperitoneal tumor extension, CT is more reliable since bowel gas not infrequently obscures the retroperitoneum on ultrasonic scanning. However, ultrasound will often provide valuable information; and whenever a solid renal mass is detected by echography using prone scans, abdominal scans should be obtained for staging pruposes.

Ultrasound followup of renal cyst puncture

The place of ultrasound and cyst puncture in the evaluation of renal masses is reviewed. Complications of cyst puncture, although rare, do occur. A review of 16 cases of renal cyst puncture revealed only 2 minor complications: in 1 case a pericystic hemorrhage occurred and in 1 case an intracystic hemorrhage was detected. Both complications were asymptomatic and detected by ultrasound. Ultrasound has proved to be an excellent means of followup for renal cyst puncture.

Enhanced detection of asymptomatic renal masses with routine tomography during excretory urography

In a prospective study of a diagnositc scheme for evaluating renal masses, it was observed that a significant number of masses (29 per cent) would have been undetected without the aid of routine tomography. The renal masses detected with the aid of tomography are either small or peripheral lesions which cause no impingement upon the renal collecting system. Without specific symptoms referable to a renal mass and without hematuria, many renal masses will be overlooked on standard excretory urography. The general improvement in diagnostic quality, the ease with which this procedure may be added to excretory urography, and the minimal expense involved would be additional factors which should justify the use of routine tomography with excretory urography in any radiology department.

Parasitic arterial supply to renal angiomyolipoma

A case of a large renal angiomyolipoma in a relatively asymptomatic female subject without tuberous sclerosis is presented. The case demonstrates a parasitized blood supply from a lumbar artery and the superior mesenteric artery, in addition to the characteristic angiographic features that have been reported previously. A parasitized blood supply to renal masses has been considered previously to be associated with malignant processes. It is emphasized that parasitization of a blood supply by a renal mass lesion is not definite evidence of malignancy.

Unsuspected renal tumors associated with renal cysts

A series of renal tumors associated with renal cysts is presented. Prior to surgical exploration appropriate diagnostic studies failed to indicate evidence of the presence of neoplastic lesions. The importance of surgical exploration of avascular "benign" renal masses is emphasized.

Gallium-67 scintigraphy for the diagnosis and localization of perinephric abscesses

Four patients with suspected perinephric abscess were evaluated by gallium-67 scintigraphy. Gallium-67 scintigraphs proved instrumental in correctly diagnosing and localizing 4 left perinephric abscesses. Roentgenographic examinations were negative in 2 cases. Gallium-67 scintigraphy can be a useful non-invasive technique to evaluate patients with suspected perinephric abscess.

Ultrasonic imaging of neoplasms

Reflected ultrasound scanning (echography) is rapidly developing into a prime tool for tumor diagnosis, outlining, and detection. The principles of echographic diagnosis of neoplasms, the accepted uses in detection and diagnosis, as well as some of the principles of internal and contour patterns are discussed. Echography is very helpful in determining the size, location, organ origin, internal characteristics, and course of neoplasms in the abdominal area, neck, and extremities. Echography is helpful in radiation therapy planning and is expected to assume an increasing role in the diagnosis and management of tumors.

Renal masses and ultrasound

Among the first 111 patients with renal masses examined by ultrasound most renal cysts (98%) and carcinomas (86%) were correctly detected. Diagnostic accuracy was high when ultrasound predicted a renal cyst (97%), but renal carcinoma accounted for only 60% of the complex echo masses found. Ultrasound was used as the primary, non-invasive test for the selection of outpatients with simple renal cysts for diagnostic puncture and for the selection of those with complex renal masses for more elaborate and expensive inpatient investigation. Ultrasound is not infallible but a safe diagnostic pathway may be drawn up in which ultrasound errors are not allowed to lead to diagnostic disasters. This approach reduced the use of arteriography for renal masses by two-thirds. With care the diagnosis of the common chance finding of a renal mass can be made simpler, safer, and cheaper.

Combined use of ultrasound and nuclear medicine techniques in kidney disease

Combined ultrasound and nuclear medicine procedures in the evaluation of urinary-tract disease are essentially limited to the kidneys. They are useful in the evaluation of patients with masses, renal failure, unilateral nonfunctioning kidney, trauma, and transplants. In our experience the combined use of these techniques has increased diagnostic accuracy and in many cases has obviated the need for more complex procedures associated with higher radiation doses. This is an especially important factor in children and in adults in the childbearing age group. We have achieved success with these modalities because of the constant communication between the referring physicians and the ultrasound and nuclear medicine divisions.