Small renal neoplasms: clinical, pathologic, and imaging features

Imaging findings of renal cell carcinoma

There are many imaging modalities used in the diagnosis of renal cell carcinoma, the most common cancer of the kidney, which accounts for approximately 2-3% of adult malignancies. Early detection of this tumor with the correct diagnostic approach using various cross-sectional imaging is very important, as are the clinical and laboratory findings. Familiarity with the spectrum of imaging findings of renal cell carcinoma will enable clinicians to consider appropriate treatment for patients and eliminate unnecessary further imaging studies.

Renal cell carcinoma : clinical features and management

In 1999 it was estimated that renal cell carcinoma (RCC) would account for 29,990 new cancer cases diagnosed in the United States (61% in men and 39% in women), and lead to 11,600 deaths. RCC accounts for 2-3% of all malignancies in adults and causes 2.3% of all cancer deaths in the United States annually (1). Approx 4% of all RCC cases are bilateral at some point in the life of the patient. Data from over 10,000 cases of renal cancer entered in the Connecticut Tumor Registry suggests an increase in the incidence of renal cancer from 1935-1989; in women the incidence increased from 0.7 to 4.2 in 100,000, and in men from 1.6 to 9.6 in 100,000 (2). Factors implicated in the development of RCC include cigarette smoking, exposure to petroleum products, obesity, diuretic use, cadmium exposure, and ionizing radiation (3-9).

Incidental findings found in "healthy" volunteers during imaging performed for research: current legal and ethical implications

Incidental findings found in "healthy" volunteers during research imaging are common and have important implications for study design and performance, particularly in the areas of informed consent, subjects' rights, clinical image analysis and disclosure. In this study, we aimed to determine current practice and regulations concerning information that should be given to research subjects when obtaining consent, reporting of research images, who should be informed about any incidental findings and the method of disclosure. We reviewed all UK, European and international humanitarian, legal and ethical agencies' guidance. We found that the guidance on what constitutes incidental pathology, how to recognise it and what to do about it is inconsistent between agencies, difficult to find and less complete in the UK than elsewhere. Where given, guidance states that volunteers should be informed during the consent process about how research images will be managed, whether a mechanism exists for identifying incidental findings, arrangements for their disclosure, the potential benefit or harm and therapeutic options. The effects of incidentally discovered pathology on the individual can be complex and far-reaching. Radiologist involvement in analysis of research images varies widely; many incidental findings might therefore go unrecognised. In conclusion, guidance on the management of research imaging is inconsistent, limited and does not address the interests of volunteers. Improved standards to guide management of research images and incidental findings are urgently required.

Characterization of contrast enhancement in the ablation zone immediately after radiofrequency ablation of renal tumors

PURPOSE

To characterize the degree of contrast enhancement within the ablation zone immediately after radiofrequency (RF) ablation of renal tumors.

MATERIALS AND METHODS

Patients with renal tumors treated with percutaneous RF ablation at one institution between January 2004 and October 2007 were retrospectively reviewed. For each tumor, computed tomography (CT) density measurements were made at four phases (noncontrast, arterial phase, parenchymal phase, and excretory phase) in each of four CT examinations (before ablation, day 0, 1 month, and 6 months).

RESULTS

A total of 36 renal tumors in 34 patients were treated with CT-guided RF ablation in 35 sessions. Before RF ablation, all tumors exhibited enhancement after intravenous administration of contrast material. The peak density was reached during the parenchymal phase, with a partial washout of contrast agent in the excretory phase. On CT images acquired immediately after RF ablation (day 0), 28 of the 36 ablated tumors (78%) exhibited clinically significant homogeneous enhancement (ie, density change >10 HU) within the ablation zone. However, contrast-enhanced CT studies performed at 1 and 6 months revealed no clinically significant enhancements in any of the 36 treated tumors (mean density changes of 4 HU at 1 month and 3 HU at 6 months).

CONCLUSIONS

Contrast-enhanced CT studies revealed a mild, temporary homogenous contrast enhancement of the ablation zone immediately after RF ablation of renal tumors, which should not be mistaken for a residual, unablated tumor. This enhancement in the ablation zone eventually disappears in follow-up contrast-enhanced CT studies.

The characterization of small hypoattenuating renal masses on contrast-enhanced CT

PURPOSE

To determine if small hypoattenuating renal masses can be characterized as simple cysts or renal cell carcinomas on contrast-enhanced computed tomography (CT).

MATERIALS AND METHODS

We retrospectively identified 20 small (<or=1.5 cm) hypoattenuating renal masses seen on contrast enhanced CT, consisting of 14 simple cysts and six renal cell carcinomas. Three independent readers recorded subjective visual impression (five-point scale from 1=definitely fluid to 5=definitely solid), CT attenuation, border (well circumscribed or ill defined), and shape (ovoid or irregular) for each lesion.

RESULTS

The overall area under the receiver operator characteristic curves for subjective visual impression, CT attenuation, border, and shape were 0.97, 0.82, 0.59, and 0.55, respectively. Using dichotomized ratings (1-2=cyst and 3-5=carcinoma), subjective impression had a sensitivity and specificity of 100% and 79-100%, respectively, for the diagnosis of renal cell carcinoma. Using a threshold of 50 Hounsfield Units (HU) or more, CT attenuation had a sensitivity and specificity of 100% and 43-64%, respectively.

CONCLUSION

Small hypoattenuating renal masses can be characterized with reasonable accuracy by subjective impression and CT attenuation; lesions that appear solid on visual inspection or have an attenuation value of 50 HU or more are likely to be renal cell carcinoma.

Bladder cancer detection with CT urography in an Academic Medical Center

PURPOSE

To evaluate the performance characteristics of computed tomographic (CT) urography for the detection of bladder cancer in patients at risk for the disease.

MATERIALS AND METHODS

Institutional review board approval was obtained for this retrospective HIPAA-compliant review of medical records of 2600 consecutive patients undergoing CT urography. Of these, 838 CT urograms in 779 patients (449 men, mean age of 62 years, range of 27-92 years; 330 women, mean age of 56 years, range of 18-86 years) evaluated for hematuria or a history of urothelial cancer, who had undergone cystoscopy within 6 months of the CT urogram, were included in the study. Clinical reports of CT urograms containing a bladder lesion interpreted as suspicious for malignancy were classified as positive. All others were classified as negative. Cystoscopy reports were classified as positive if a lesion underwent biopsy or was resected or negative if no lesion was detected. Performance characteristics for both CT urography and cystoscopy were determined by using pathologic findings or clinical follow-up as the reference standard. Ninety-five percent confidence intervals were estimated for each test characteristic.

RESULTS

The overall sensitivity, specificity, accuracy, positive predictive value, and negative predictive value (NPV) for bladder cancer detection were 79% (117 of 149), 94% (649 of 689), 91% (766 of 838), 75% (117 of 157), and 95% (649 of 681) for CT urography and 95% (142 of 149), 92% (634 of 689), 93% (776 of 838), 72% (142 of 197), and 99% (634 of 641) for cystoscopy. The NPV of CT urography was higher in patients evaluated for hematuria alone (98%, 589 of 603). However, the accuracy of CT urography was considerably lower in patients with a prior urothelial malignancy (78%, 123 of 158).

CONCLUSION

CT urography is an accurate noninvasive test for detecting bladder cancer in patients at risk for the disease. The high NPV of CT urography in patients with hematuria may obviate cystoscopy in selected patients.

Percutaneous Core Biopsy for Renal Masses: Indications, Accuracy and Results

PURPOSE

We evaluated the results, accuracy and clinical incidence of our standard procedure of percutaneous biopsy for solid renal masses.

MATERIALS AND METHODS

From March 1999 to April 2005, 119 percutaneous core biopsies of renal masses were performed. Biopsies were proposed when there was no formal evidence for a carcinoma diagnosis on computerized tomography.

RESULTS

Benign lesions were diagnosed in 24 biopsies (20.1%), including oncocytoma in 13, angiomyolipoma in 5 and chronic pyelonephritis in 5. Malignancy was identified in 70 biopsies (58.8%), including 57 renal carcinomas (conventional renal cell in 41, papillary in 12 and chromophobe in 4), 4 transitional cell carcinomas, 8 metastases and 1 lymphoma. For 25 biopsies (21%) no accurate diagnosis was possible, including 12 that showed inflammatory tissue and 13 with normal or necrotic tissue. These inconclusive biopsies prompted repeat biopsy in 13 patients, in whom a total of 11 malignant lesions were diagnosed. A total of 64 nephrectomies were performed with a biopsy accuracy for histopathological tumor type and Fuhrman nuclear grade of 86% and 46%, respectively. A period of watchful waiting was proposed for 31 patients (34.2%) and no renal malignancies were found. Computerized tomography showed stabilization or disappearance of the initial renal mass.

CONCLUSIONS

Percutaneous renal tumor biopsies are safe, cost-effective and often conclusive for an acute histological diagnosis. This procedure could be decisive for choosing the optimal treatment, particularly to avoid nephrectomy for benign lesions. Biopsies should not be considered a routine procedure but they could be indicated when there is a lack of radiological evidence in elective patients.

The role of computerized tomographic urography in the initial evaluation of hematuria

PURPOSE

We determined the usefulness of computerized tomographic urography for the initial evaluation of patients with hematuria as an alternative to excretory urography.

MATERIALS AND METHODS

A total of 259 patients (140 men and 119 women), age range 20 to 100 (mean 59.4) years, underwent computerized tomographic urography for the evaluation of hematuria and were available for followup. A cohort of 253 patients (153 men, 100 women), age range 21 to 92 (mean 57.6) years, underwent conventional excretory urography and were evaluated for comparison.

RESULTS

A source of hematuria was identified in 107 patients (41.3%) in the computerized tomographic urography cohort and in 103 patients (40.7%) in the excretory urography cohort. Computerized tomographic urography alone identified a source of hematuria in 25.5% of these patients with the most commonly diagnosed lesions being renal calculi (18.9%), ureteral calculi (2.7%) and renal pelvic masses (2.3%) in the upper tract (0.94 sensitivity), and bladder masses (8.1%), prostatic abnormalities (5.4%) and inflammatory disorders (3.5%) in the lower tract (0.40 sensitivity, 0.99 specificity). The overall detection rate (19.5%), most commonly diagnosed lesions, and lower urinary tract sensitivity and specificity were similar in the excretory urography cohort. However, excretory urography exhibited a markedly lower sensitivity in detecting upper tract lesions (0.50).

CONCLUSIONS

Computerized tomographic urography exhibited a significantly higher sensitivity than conventional excretory urography in detecting upper tract pathology (94.1% vs 50%). However, sensitivity for detecting lower tract lesions was low (40% or less), suggesting that computerized tomographic urography offers a comprehensive alternative to excretory urography but does not obviate the need for adjunctive cystourethroscopy for accurate evaluation of the lower urinary tract.

Renal Mass Core Biopsy: Accuracy and Impact on Clinical Management

OBJECTIVE

The objective of our study was to determine the accuracy of imaging-guided percutaneous renal mass biopsy and its impact on clinical management.

MATERIALS AND METHODS

With institutional review board approval, we retrospectively reviewed imaging-guided renal biopsies performed by radiologists at our institution between February 1999 and July 2005. Patient records, pathology reports, and imaging studies were reviewed. Concordance of biopsy diagnosis and follow-up data was assessed. Significant impact on clinical management was determined in collaboration with two experienced urologists and was defined as a change from no therapy to therapy, including surgery, tumor ablation, chemotherapy, or radiation.

RESULTS

Two hundred seventy-six renal biopsies were performed during the study period. Of these, 123 were random biopsies and fine-needle technique was used for one; these 124 were excluded. One hundred fifty-two renal mass biopsies were performed using coaxial 18-gauge core needle technique in 125 patients (55 women, 70 men; average age, 60 years; range, 28-90 years). There were two (1.3%) postprocedural hematomas (one [0.7%] requiring blood transfusion) and one (0.7%) delayed renal pseudoaneurysm attributed to biopsy. No tumor seeding was identified. In 85 biopsies (56%), malignant neoplasm was found, 61 biopsies (40%) yielded benign findings, and six (4%) were nondiagnostic. The sensitivity for malignancy was 97.7%; specificity, 100%; positive predictive value, 100%; and negative predictive value, 100%. At least 92 (60.5%) biopsy results significantly impacted clinical management.

CONCLUSION

Imaging-guided percutaneous core needle biopsy of renal masses is safe and highly accurate. Tissue diagnosis alters clinical decision making in a majority of the cases and may allow a number of unnecessary nephrectomies to be avoided.

Radiofrequency Ablation of Small Renal Cell Carcinomas Using Multitined Expandable Electrodes: Preliminary Experience

PURPOSE

Radiofrequency ablation is a minimally invasive, nephron-sparing option for renal cell carcinoma (RCC) in poor surgical candidates. We report our contemporary experience with RCC radiofrequency ablation using multitined expandable electrodes along with an aggressive treatment strategy to displace adjacent viscera away from probe tines. Involution of the treatment zone was assessed over time.

MATERIALS AND METHODS

Over a 36-month period, a quality-assurance database identified 22 patients with 26 sporadic RCC who underwent 43 ablations during 27 radiofrequency ablation sessions. The mean age of the cohort was 71 years (range, 47-89 y). Mean RCC diameter was 2.2 cm (range, 1-4 cm). Twenty-six of radiofrequency ablation sessions were performed using multitined expandable electrodes. All ablations used CT guidance with moderate sedation. Adjunctive techniques used during ablation were recorded, as were instances in which ablation mandated penetration of tines beyond the kidney margin. Post-treatment ablation zones were measured from CT/MR images to evaluate serial involution and treatment response.

RESULTS

Technical success in targeting and ablation was 100%. Follow-up periods ranged from 1 to 31 months (mean, 11.2). During this period, one patient presented with marginal local recurrence and underwent repeat radiofrequency ablation. Adjunctive techniques in four patients included water injection for displacement of the tail of the pancreas (n = 1) or descending colon (n = 3). Deliberate penetration of tines beyond the margins of the kidney was performed in 41% of cases; no hemorrhage occurred in these cases. No major complications occurred. Minor complications occurred in 17% of patients, including asymptomatic pneumothorax, perirenal hematomas, subcutaneous hematoma, and subcutaneous abscess. After 6 months, mean involution of the ablation zone was 15% from baseline volume per year.

CONCLUSION

Multitined expandable radiofrequency electrodes produce a high rate of local control for small RCCs with a low complication rate, even when tine penetration of the kidney is required for an adequate tumor treatment margin. Adjacent organs can be protected with adjunctive percutaneous maneuvers.

Conservative management of incidental contrast-enhancing renal masses as safe alternative to invasive therapy

OBJECTIVES

To describe small contrast-enhancing renal masses suggestive of cancer that were managed conservatively with watchful waiting and serial computed tomography scans. Advanced diagnostic imaging has led to the increased incidental detection of renal masses in patients whose multiple comorbid conditions preclude invasive management.

METHODS

A retrospective review was conducted of 29 consecutive patients with 29 incidentally detected asymptomatic renal masses less than 3.5 cm in diameter that were managed conservatively with watchful waiting (because of patient wishes or multiple comorbid conditions) and serial computed tomography scans.

RESULTS

The average patient age was 70 years (range 51 to 88), and the average duration of follow-up imaging was 32 months (range 10 to 89). The average number of follow-up computed tomography scans was 4.9 per patient (range 1 to 11). The average width of the renal masses at diagnosis was 1.83 cm (range 0.4 to 3.5), and the average change in size per year was 0.12 cm for all patients. Four patients underwent radical nephrectomy because of growth of the renal mass (n = 1) or patient wishes (n = 3). The histologic findings in 3 of these 4 patients were consistent with renal cell carcinoma. Two patients underwent radiofrequency ablation of the masses. At last follow-up, metastatic disease had not developed in any patient, and no patient had died of renal cell carcinoma. Two patients had died of other causes.

CONCLUSIONS

The results of our study showed that when comorbid conditions or patient wishes preclude invasive treatment, contrast-enhancing renal masses less than 3.5 cm wide that are suggestive of cancer can be safely managed with watchful waiting and serial computed tomography scans.

Small renal oncocytoma with central cystic degeneration

A case of a small renal oncocytoma with central cystic degeneration, 15 mm in diameter, is reported. Contrast-enhanced computed tomography showed the tumor contained a central hypoattenuating region and had an irregular, heterogeneously enhanced wall. Magnetic resonance images showed a well-circumscribed lesion and the T(1)-weighted image indicated medium signal intensity, whereas the T(2)-weighted image indicated slight hypointensity. Both T(1)- and T(2)-weighted images showed central hyperintensity. Our preoperative diagnosis was renal cell carcinoma originating in a renal cyst wall or cystic renal cell carcinoma. Nephrectomy was performed because frozen-section examination did not completely rule out malignancy. The final pathological diagnosis of the entire surgical specimen was renal oncocytoma with cystic degeneration. To our knowledge, this is the 14th case of renal oncocytoma with central cystic degeneration reported in the published works. We discuss herein the variant forms of oncocytoma and difficulties with their preoperative diagnosis, especially when the tumor is small.

Prospective analysis of computerized tomography and needle biopsy with permanent sectioning to determine the nature of solid renal masses in adults

PURPOSE

We prospectively determined the accuracy of computerized tomography (CT) and needle biopsy of solid renal masses.

MATERIALS AND METHODS

A total of 100 patients with a solid renal mass who were scheduled for operation were prospectively evaluated. CT was performed before radical or partial nephrectomy. Biopsy of the surgical specimens was done twice through the tumor using an 18 gauge biopsy gun. Specimens were sent for permanent section and review by 2 pathologists blinded to each other and to the whole tissue specimens. Images were reviewed by 2 radiologists blinded to each other and to the results of pathological analysis. Results of CT and permanent biopsy were compared with the results of whole tissue specimen analysis.

RESULTS

Specimens were obtained from 59 radical and 41 partial nephrectomies. Malignant neoplasms were present in 85 patients (85%). Overall accuracy was 77% and 72%, the nondiagnostic rate was 20% and 21%, sensitivity was 81% and 83%, and specificity was 60% and 33%. For the 2 radiologists overall accuracy was 60% and 66%, the nondiagnostic rate was 31% and 23%, sensitivity was 70% and 77%, and specificity was 20% and 20%, respectively.

CONCLUSIONS

Overall permanent biopsy results were accurate in more than 72% of cases and CT was accurate in more than 60%. However, because the nondiagnostic rate for CT and needle biopsy was 20% and 31%, respectively, and specificity was low, we do not recommend routine preoperative CT and subsequent needle biopsy to guide treatment decision making. Rather, cases must be decided individually.

Nephron-sparing surgery

The curative management of renal cell carcinoma remains surgical. Recent advances in imaging and increased use of cross-sectional imaging modalities have led to an increased detection of incidental renal cell carcinomas. There is little debate regarding the role of nephron-sparing surgery (NSS) when absolutely indicated. Radical nephrectomy is still considered by many as the treatment of choice for localized renal cell carcinoma in the setting of a normal contralateral kidney. However, there is growing evidence that in the correct patient, the use of NSS in this setting is justified. Therefore, the indications of NSS have evolved in the past decade. Recent data indicate that radical nephrectomy and NSS provide effective and equivalent curative treatment for most renal cell carcinomas, especially those 4 cm or smaller. These data, along with new, refined surgical techniques, new studies regarding the biology of renal cell carcinoma and true incidence of occult multifocality, and earlier diagnosis make NSS an attractive consideration for the practicing urologist.

Incidental detection of preclinical renal tumors with electron beam computed tomography: report of 26 consecutive operated patients

PURPOSE

The purpose of this work was to describe the positive predictive value of electron beam CT (EBCT) for diagnosis of solid renal tumors.

METHOD

Among 11,932 consecutive patients undergoing screening EBCT, 27 cases met EBCT criteria for solid renal tumors. Twenty-six of 27 patients underwent surgery.

RESULTS

Surgical pathology identified 25 solid renal tumors and 1 adrenal hemorrhage with thrombus. Twenty tumors were classified as T1N0M0, one was T2N0M0, and one was T3aN0M0. All tumor patients are clinically well at 1-41 months (mean 17 months) postoperatively. None of the patients had clinical signs or symptoms characteristic of renal malignancy.

CONCLUSION

EBCT is an effective tool for detection of solid renal tumors in a healthy outpatient population (positive predictive value 0.96). The detection rate is low [0.2% (26/11,932) at our facility] in patients undergoing EBCT for other indications. The cost-effectiveness and sensitivity of this technique for solid renal tumor detection among various populations remain to be determined.

Small renal masses: assessment of lesion characterization and vascularity on dynamic contrast-enhanced MR imaging with fat suppression

OBJECTIVE

The aim of our study was to characterize renal lesions equal to or smaller than 3.0 cm using dynamic contrast-enhanced MR imaging with fat suppression by means of quantitative analysis of signal intensity.

MATERIALS AND METHODS

We retrospectively reviewed the MR imaging examinations of 35 patients (20 with renal cell carcinoma, eight with angiomyolipoma, and seven with complicated cysts) who were studied with spin-echo and dynamic fat-suppressed gradient-recalled echo MR sequences, before and after the administration of gadopentetate dimeglumine. Every 30 sec after contrast injection, we measured the lesion percentage of enhancement and the ratio of contrast (lesion-renal cortex signal intensity difference) to noise.

RESULTS

Ten renal cell carcinomas were classified as hypervascular (enhancement greater than that of renal cortex) and 10 as hypovascular. The percentage of enhancement of hypervascular carcinomas was similar to that of renal cortex until 150 sec and greater in the late sequences (180-210 sec, p < 0.01). Hypovascular carcinomas had a lower percentage of enhancement than hypervascular carcinomas (60-210 sec, p < 0.005). Angiomyolipomas, after an early enhancement peak, showed values similar to those of hypovascular carcinomas. Complicated cysts had very low enhancement (p < 0.001). The baseline contrast-to-noise ratio was negative for all lesions (hypointensity with respect to renal cortex). After gadolinium injection, the contrast-to-noise ratio of hypervascular carcinomas rose, becoming positive after 150 sec. Until 60 sec, the contrast-to-noise ratio of hypovascular carcinomas declined slightly, whereas that of angiomyolipomas and cysts fell sharply; then the three curves remained stable (60-210 sec, p < 0.05 for all matches except angiomyolipomas versus cysts).

CONCLUSION

Quantitative analysis of signal intensity variations during dynamic contrast-enhanced MR imaging with fat suppression can be useful in the characterization of small renal lesions.

Spontaneous rupture of renal tumours: the role of imaging in diagnosis and management

This study aimed to evaluate whether patients presenting with spontaneous haemorrhage from renal tumours could be accurately diagnosed and initially managed conservatively, and evaluate the role of imaging in guiding the timing and type of subsequent operation. The clinical features, imaging findings and management of seven patients presenting with spontaneous rupture of renal tumour over a 5-year period were reviewed. The information from various imaging studies was evaluated in relation to the subsequent course of intervention. The tumours consisted of six angiomyolipomas and one renal cell carcinoma. In all cases, imaging studies were diagnostic, with computed tomography being the most useful single modality. Emergency surgery was required in one patient for evacuation of suspected infected haematoma and wedge excision of angiomyolipoma. Three elective nephrectomies were performed, while three other patients with ruptured angiomyolipoma were treated conservatively and remained well, without any intervention. In conclusion, patients presenting with spontaneous rupture of renal tumour can be managed conservatively initially. Imaging facilitates accurate pre-operative diagnosis, which was angiomyolipoma in all but one patient in this series. The subsequent intervention can be tailored according to the lesion type and the anticipated risk of re-haemorrhage.

Computed tomography characterization of renal cell tumors in correlation with histopathology

RATIONALE AND OBJECTIVES

The authors distinguish the histomorphologic subtypes of renal cell tumors (RCTs) by computed tomography (CT).

METHODS

In a consensus conference between radiologists, pathologists, and urologists, the CT criteria of the various subtypes of RCTs (clear cell, chromophilic cell, chromophobic cell renal carcinoma and oncocytoma) were established. Computed tomography scans of 65 resected RCTs were reevaluated independently by seven radiologists. Using a numerical scoring system, they first attempted to differentiate clear cell from nonclear cell RCTs. A further attempt then was made to classify each tumor into one of the four categories.

RESULTS

The sensitivity for the diagnosis of clear cell RCT was 72.5% (213 of 294 true-positive findings) and 82% (132 of 161 true-positive findings) for the nonclear cell group. For tumors more than 3 cm in diameter the sensitivities were 80.25% for the clear cell group and 80.7% for the nonclear cell group. Specific differentiation into the four subtypes was not possible. Oncocytomas were classified correctly in only 6 of 49 observations (12.2%).

CONCLUSIONS

Small clear cell tumors often fail to show the CT characteristics that would permit an accurate classification. In tumors measuring 3 cm or more, differentiation between clear cell and nonclear cell types by means of CT criteria is possible. Nevertheless, as RCTs show a great variation in appearance, a differentiation into subtypes of the nonclear cell RCTs cannot be accomplished by CT. Using a uniform examination protocol and spiral scanning technique, the sensitivity of CT in the diagnosis of the subtypes of RCTs may be able to be further increased. Some tumors, especially oncocytomas, undoubtedly will remain diagnostic dilemmas.

Radiologic evaluation of small and indeterminant renal masses

A common problem in radiologic and urologic practice today is what to do with the small or indeterminant renal mass. Whether found incidentally or sought after because of patient symptomatology, these lesions present a challenge in diagnosis and management. This article outlines the scope of the problem, illustrates representative lesions, suggests imaging and management strategies culled from personal experience, and provides a review of available literature.

Prognostic value of clinical parameters for renal cell carcinoma

– Clinical evaluation of patients with kidney tumours should provide several parameters with possible prognostic value, such as age, sex, incidental discovery, duration of symptoms, weight loss, fever, disease-free interval, performance status, elevated ESR, hypercalcemia, elevated gamma-enolase, local tumour extension, invasion of renal vein and inferior vena cava, lymphatic metastases, distant metastases, tumour dimension, multicentricity, bilaterality and growth velocity. Some of these factors correlate to prognosis in univariate statistical analysis; in multivariate analysis, however, tumour stage is the best prognostic factor, while the other parameters show less or no prognostic value. Besides tumour stage, parameters with an independent value are performance status, weight loss, elevated ESR. Using these prognostic factors, patients can be divided into groups with different prognosis and treatment.

CT after enucleation of renal cell carcinoma

Computed tomography (CT) was performed in 28 patients 2 weeks to 120 months after enucleation of renal cell carcinoma. The postoperative defect could be exactly localized in all patients. A wedge-shaped (N = 11) or concave (N = 9) morphology was typical. No dependence between morphology of the defect and localization or size of the tumor or the operative technique was observed. The defects were smaller (1.9 cm) than the original prominent tumors (3.6 cm). Defect size was dependent on the operative technique: closure by suture of the renal capsule in smaller defects or by fat flap in larger ones. Postoperative hematomas or delayed perfusion in the adjacent parenchyma were seen in five patients. Tumor recurrence was correctly diagnosed in one patient.

Isotope diagnostics, CT and MR in urinary tract diseases of infants and children

Ninety-nine isotope, 4 CT and 10 MR examinations were carried out in 1990 to test urogenital disorders in infants and children. The procedures are described with sidelights on indication, difficulties of technical nature and comparison with internationally published reports. An examination strategy is devised, with estimation of its effectiveness in the follow-up and after-care.

Renal cell carcinoma in childhood

The imaging features of renal cell carcinoma in 4 young patients (age 7 to 14 years) are described. A high proportion (75%) showed calcification on plain radiographs or computed tomography (CT). Both patients who underwent CT showed well defined high density tumours which were also echogenic on ultrasound examination. These findings are significantly different to those most commonly seen on studies of the tumour in adults.

Pitfalls in sonography of renal masses

This paper reviews selected pitfalls in the use of ultrasound (US) for evaluating renal masses without attempting a comprehensive topic review.