Imaging of kidney cancer

Experiences of robot assisted thrombectomy with 2-year follow-up

BACKGROUND

No consensus has been reached on operative procedures since a limited case series of robot-assisted inferior vena cava thrombectomy (RA-IVCT) and robot-assisted radical nephrectomy (RA-RN) have been described.

METHODS

The clinical data of 21 patients who underwent RA-IVCT and RA-RN were retrieved from the database. Preoperative preparation was used for assessment of the tumour. Surgical procedures were recorded, and operative skills were summarised.

RESULTS

The median IVC clamping time was 23 min, and IVC wall invasion was pathologically found in 2 cases. The mean postoperative hospital stay was 8.4 days and most patients recovered to full ambulation and oral feeding on the fourth day. None of the patients had liver or kidney dysfunction at the last follow-up (median, 24 months).

CONCLUSION

RA-IVCT presents technical challenges to surgeons. IVC control is an important part of the surgical process and different sides require different techniques.

Mesenchymal-Epithelial Transition Kinase Inhibitor Therapy in Patients with Advanced Papillary Renal-Cell Carcinoma: A Systematic Review and Meta-Analysis

Papillary subtypes of renal-cell carcinoma (pRCC) represent 10-15% of the cases and commonly have MET alterations. This systematic review and single-arm meta-analysis evaluated MET inhibitor therapy (METi) efficacy and safety in adults with confirmed advanced pRCC. The search strategy included PubMed, Web-of-science, Cochrane, and Scopus. We used the DerSimonian/Laird random effect model for all analyses; p-value < 5% was considered significant, and heterogeneity was assessed with I2. Three clinical trials and six cohort studies were included with 504 patients; 31% were MET-driven. Our pooled analysis demonstrated an objective response rate (ORR) in MET-driven, MET-independent, and overall patients of: 36% (95%CI: 10-62), 0% (95%CI: 0-3), and 21% (95%CI: 1-41), respectively. One-year disease control and progression-free survival rates were, respectively, 70% (95%CI: 52-88) and 15% (95%CI: 10-20). Twelve- and twenty-four-month survival rates were, respectively, 43% (95%CI: 23-64) and 10% (95%CI: 0-30). The prevalence of adverse events of any grade and grades 3-5 were 96% (95%CI: 91-100) and 44% (95%CI: 37-50), respectively. We suggest METi has anti-tumor activity and is tolerable in patients with advanced pRCC.

Radiological Features of T1a Renal Cell Carcinoma on Axial Unenhanced Computed Tomography

CT has become a commonly used diagnostic procedure in clinical practice, particularly in emergency healthcare delivery. Accordingly, the increase in CT usage has increased the likelihood of incidental detections (ID) of renal cell carcinomas (RCCs). This article discusses key points and limitations associated with the diagnosis and characterization of T1a RCC (≤4 cm in diameter) and shows how to improvise on the differentiation of T1a RCC with unenhanced CT (UE-CT). We retrospectively reviewed UE-CT findings of cases associated with the histopathologic diagnosis of T1a RCC and examined the discrimination capacity and radiological characteristics with regard to small RCCs (SRCCs). Detection and characterization of T1a RCC based on UE-CT are not easy in many cases due to limitations in CT findings, but there are notable radiological features to facilitate detection and differentiation. The growth pattern is important for the detection of SRCCs. Internal characteristic features (average attenuation, heterogeneity) are useful for the characterization of the RCC. In addition, CT image visualization techniques may help improve the detectability of RCCs on UE-CT. Radiological features are important in detecting SRCCs and facilitating further examination. In this study, we discuss some cases of T1a RCCs and evaluate the radiological characteristics of the tumors seen on UE-CT.

Diagnostic test accuracy of ADC values for identification of clear cell renal cell carcinoma: systematic review and meta-analysis

OBJECTIVES

To perform a systematic review on apparent diffusion coefficient (ADC) values of renal tumor subtypes and meta-analysis on the diagnostic performance of ADC for differentiation of localized clear cell renal cell carcinoma (ccRCC) from other renal tumor types.

METHODS

Medline, Embase, and the Cochrane Library databases were searched for studies published until May 1, 2019, that reported ADC values of renal tumors. Methodological quality was evaluated. For the meta-analysis on diagnostic test accuracy of ADC for differentiation of ccRCC from other renal lesions, we applied a bivariate random-effects model and compared two subgroups of ADC measurement with vs. without cystic and necrotic areas.

RESULTS

We included 48 studies (2588 lesions) in the systematic review and 13 studies (1126 lesions) in the meta-analysis. There was no significant difference in ADC of renal parenchyma using b values of 0-800 vs. 0-1000 (p = 0.08). ADC measured on selected portions (sADC) excluding cystic and necrotic areas differed significantly from whole-lesion ADC (wADC) (p = 0.002). Compared to ccRCC, minimal-fat angiomyolipoma, papillary RCC, and chromophobe RCC showed significantly lower sADC while oncocytoma exhibited higher sADC. Summary estimates of sensitivity and specificity to differentiate ccRCC from other tumors were 80% (95% CI, 0.76-0.88) and 78% (95% CI, 0.64-0.89), respectively, for sADC and 77% (95% CI, 0.59-0.90) and 77% (95% CI, 0.69-0.86) for wADC. sADC offered a higher area under the receiver operating characteristic curve than wADC (0.852 vs. 0.785, p = 0.02).

CONCLUSIONS

ADC values of kidney tumors that exclude cystic or necrotic areas more accurately differentiate ccRCC from other renal tumor types than whole-lesion ADC values.

KEY POINTS

• Selective ADC of renal tumors, excluding cystic and necrotic areas, provides better discriminatory ability than whole-lesion ADC to differentiate clear cell RCC from other renal lesions, with area under the receiver operating characteristic curve (AUC) of 0.852 vs. 0.785, respectively (p = 0.02). • Selective ADC of renal masses provides moderate sensitivity and specificity of 80% and 78%, respectively, for differentiation of clear cell renal cell carcinoma (RCC) from papillary RCC, chromophobe RCC, oncocytoma, and minimal-fat angiomyolipoma. • Selective ADC excluding cystic and necrotic areas are preferable to whole-lesion ADC as an additional tool to multiphasic MRI to differentiate clear cell RCC from other renal lesions whether the highest b value is 800 or 1000.

T1a renal cell carcinoma on unenhanced CT: analysis of detectability and imaging features

Background

Increasing use of unenhanced computed tomography (CT) has been associated with the increasing incidental detection of renal cell carcinoma (RCC) at an earlier stage.

Purpose

To evaluate the characteristics in detecting and differentiating T1a RCCs on unenhanced CT.

Material and Methods

We retrospectively reviewed 68 patients with 68 T1a RCCs and 39 benign regions. Two radiologists interpreted the images on unenhanced axial CT and performed a blinded and independent review of T1a RCCs. The readers evaluated the presence of RCC and differentiated the detected lesions.

Results

The consensus of two readers detected 53 (78%) RCCs. Of the 53 detected RCCs, 42 (62%) RCCs were correctly diagnosed and 11 (16%) masses were misdiagnosed as benign. Of the 39 benign regions, 29 (74%) cysts were diagnosed correctly, but 10 (26%) cysts were misdiagnosed as malignant. The following values of the radiologists were obtained by consensus: sensitivity = 61.8% (42/68); specificity = 74.4% (29/39); positive predictive value = 80.8% (42/52); negative predictive value = 55.0% (29/55); accuracy = 66.4% (71/107). The receiver operating characteristic curve of consensus was 0.754. Inter-observer correlation was κ = 0.849. There was a significant difference in tumor size (P = 0.019) and the contour type of tumor (P = 0.0207) between correctly diagnosed RCCs and not correctly diagnosed RCCs.

Conclusion

Our findings showed that tumor size and contour type could affect the detection and differentiation of T1a RCC on unenhanced CT. To detect and differentiate T1a RCC on unenhanced CT is difficult. However, the findings from this study may help detection of RCCs on unenhanced CT.

Review of renal cell carcinoma and its common subtypes in radiology

Representing 2%-3% of adult cancers, renal cell carcinoma (RCC) accounts for 90% of renal malignancies and is the most lethal neoplasm of the urologic system. Over the last 65 years, the incidence of RCC has increased at a rate of 2% per year. The increased incidence is at least partly due to improved tumor detection secondary to greater availability of high-resolution cross-sectional imaging modalities over the last few decades. Most RCCs are asymptomatic at discovery and are detected as unexpected findings on imaging performed for unrelated clinical indications. The 2004 World Health Organization Classification of adult renal tumors stratifies RCC into several distinct histologic subtypes of which clear cell, papillary and chromophobe tumors account for 70%, 10%-15%, and 5%, respectively. Knowledge of the RCC subtype is important because the various subtypes are associated with different biologic behavior, prognosis and treatment options. Furthermore, the common RCC subtypes can often be discriminated non-invasively based on gross morphologic imaging appearances, signal intensity on T2-weighted magnetic resonance images, and the degree of tumor enhancement on dynamic contrast-enhanced computed tomography or magnetic resonance imaging examinations. In this article, we review the incidence and survival data, risk factors, clinical and biochemical findings, imaging findings, staging, differential diagnosis, management options and post-treatment follow-up of RCC, with attention focused on the common subtypes.

Postoperative distal ureteric and bladder cuff recurrence in a Grade I renal transitional cell carcinoma diagnosed and restaged by fluorodeoxyglucose positron emission tomography-computed tomography

A 56-year-old male having Grade I transitional cell carcinoma (TCC) of left kidney, postleft nephrectomy and upper 1/3(rd) ureterectomy presented with painless hematuria. Restaging fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) revealed abnormal linear FDG uptake in the lower 2/3(rd) of the left ureter and in the bladder adjacent to the left vesicoureteric junction, no locoregional adenopathy nor distant metastases (Figures 1 and 2- left column). Patient underwent left lower ureterectomy with partial cystectomy. Postoperative histopathology was TCC. Instillation of Bacillus Calmette-Guérin injection in the bladder was done postoperatively. A follow-up FDG PET/CT scan performed 3 months postoperatively was revealed no abnormal focal FDG uptake in the whole body revealing disease free status. FDG PET was helpful in diagnosing tumor recurrence in the distal remnant ureter. This case attempts to highlight the role of FDG PET/CT in follow-up, residual and recurrence evaluation.

Unenhanced CT for the detection of renal cell carcinoma: effect of tumor size and contour type

PURPOSE

To evaluate effect of tumor size and contour type for the detection of renal cell carcinoma (RCC) on unenhanced CT.

METHODS

This retrospective institutional review board approved study that includes 111 patients with RCC and 100 patients without RCC who underwent unenhanced CT. Two readers performed a blinded and independent review of the presence of RCC on unenhanced CT. The area under the receiver operating characteristic curves (AUC) was compared by tumor size (<3 cm: small, or ≥3 cm: large) and contour type (endophytic, mesophytic, or exophytic).

RESULTS

For tumor size, the AUC for small RCC (0.70 and 0.78, for reader 1 and reader 2) was significantly lower than that for large RCC (0.97 and 0.99, for reader 1 and reader 2) (p < 0.001). As for contour type of tumor, the AUC for endophytic RCC (0.60 and 0.71, for reader 1 and reader 2) was significantly lower than that for mesophytic RCC (0.95 and 0.98, for reader 1 and reader 2) and exophytic RCC (0.98 and 0.99, reader 1 and reader 2) (p < 0.001).

CONCLUSION

On unenhanced CT, tumor size and contour type can affect the detection of RCC. While most large or exophytic RCC can be easily detected, the detection of small and endophytic RCC is highly limited.

Renal mucinous tubular and spindle cell carcinoma: a report of 8 cases and review of the literature

Background

Mucinous tubular and spindle cell carcinoma of kidney (MTSCC-K) is a rare variant of renal tumor. The current data show most of MTSCCs are of low malignant potential and rare cases metastatic to lymph nodes have been reported; however, the recorded computed tomography (CT) and follow up data are limited.

Material and method

In the present study, we retrospectively analyzed CT and clinicopathological data of eight patients with renal MTSCC-K.

Results

A total of eight cases, including six females and two males, were included in this analysis with a mean age of 48.4 (range 25 to 81) years. Mean tumor size was 4.2 (range 2.5 to 10.0) cm. Preoperative CT demonstrated that all tumors were slightly enhanced on both corticomedullary and nephrographic phase, which was different from many other renal cell carcinomas. Three of them were treated with open radical nephrectomy, three with laparoscopic radical nephrectomy and the other two with laparoscopic partial nephrectomy. No postoperative therapy was applied. Patients were followed up for 15 to 64 months and there was no evidence of recurrence and metastasis.

Conclusions

The MTSCC-K has special clinicopathological characteristics, low degree of malignancy and relative good prognosis. The diagnosis mainly depends on the histopathological examination and CT may help to differentiate with papillary renal cell carcinoma. Surgical treatment is recommended and additional therapies are not necessary.

Virtual slides

The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/8435581771088249.

The value of "liver windows" settings in the detection of small renal cell carcinomas on unenhanced computed tomography

OBJECTIVE

To assess if "liver window" settings improve the conspicuity of small renal cell carcinomas (RCC).

METHODS

Patients were analysed from our institution's pathology-confirmed RCC database that included the following: (1) stage T1a RCCs, (2) an unenhanced computed tomography (CT) abdomen performed ≤ 6 months before histologic diagnosis, and (3) age ≥ 17 years. Patients with multiple tumours, prior nephrectomy, von Hippel-Lindau disease, and polycystic kidney disease were excluded. The unenhanced CT was analysed, and the tumour locations were confirmed by using corresponding contrast-enhanced CT or magnetic resonance imaging studies. Representative single-slice axial, coronal, and sagittal unenhanced CT images were acquired in "soft tissue windows" (width, 400 Hounsfield unit (HU); level, 40 HU) and liver windows (width, 150 HU; level, 88 HU). In addition, single-slice axial, coronal, and sagittal unenhanced CT images of nontumourous renal tissue (obtained from the same cases) were acquired in soft tissue windows and liver windows. These data sets were randomized, unpaired, and were presented independently to 3 blinded radiologists for analysis. The presence or absence of suspicious findings for tumour was scored on a 5-point confidence scale.

RESULTS

Eighty-three of 415 patients met the study criteria. Receiver operating characteristics (ROC) analysis, t test analysis, and kappa analysis were used. ROC analysis showed statistically superior diagnostic performance for liver windows compared with soft tissue windows (area under the curve of 0.923 vs 0.879; P = .0002). Kappa statistics showed "good" vs "moderate" agreement between readers for liver windows compared with soft tissue windows.

CONCLUSION

Use of liver windows settings improves the detection of small RCCs on the unenhanced CT.

Preoperative evaluation of perinephric fat invasion in patients with renal cell carcinoma: correlation with pathological findings

The purpose of this study was to evaluate the role of computed tomography (CT) and magnetic resonance imaging (MRI) scans in predicting perinephric fat invasion. Preoperative CT and MRI scans of 109 patients were assessed retrospectively by two radiologists focusing on perinephric fat invasion. Findings were correlated with histopathology. Perinephric fat involvement on imaging was reported in 55 cases, and postoperative pathology record confirmed it in 32 patients. The sensitivity, specificity, positive predictive value, and negative predictive value were 82%, 63%, 48%, and 89%, respectively, with a P value of .001. To conclude, cross-sectional imaging techniques can reliably predict perinephric fat invasion in renal carcinomas preoperatively.

Renal MALT lymphoma associated with Waldenström macroglobulinemia

Mucosa associated lymphoid tissue lymphoma (MALT lymphoma) is mostly seen in the gastrointestinal tract; origin from the kidney is extremely rare. Waldenström macroglobulinemia (WM) is a clinicopathologic syndrome denoted by the presence of monoclonal gammopathy in the serum, typically caused by lymphoproliferative disorder. Literature review did not find any report of renal MALT lymphoma accompanied by WM. Herein, for the first time, we report a 72 year-old female patient with a history of chronic kidney disease, presenting with solitary renal mass; MALT lymphoma was confirmed by pathological examination. A serology study identified the presence of WM. No manifestation of hyperviscosity syndrome was noted. Bone marrow biopsy disclosed the concurrent systemic involvement. Her treatment response was uneventful and the renal mass responded with regressive change in size after chemotherapy. The renal function remained stable during follow-up. MALT lymphoma should be considered as an underlying pathology of isolated renal mass. Furthermore, patients with MALT lymphoma should be screened for Waldenström macroglobulinemia and hyperviscosity syndrome.

Diagnosis and treatment of primary adult renal sarcoma

OBJECTIVE

To investigate the clinical characteristics of primary adult renal sarcoma.

METHODS

A total of 1654 cases with adult renal tumors were treated during 1985 to 2009 in Peking Union Medical College Hospital. Of all, 17 cases were diagnosed as primary renal sarcoma and underwent radical nephrectomy. The clinical features of 17 such patients were retrospectively analyzed.

RESULTS

The first symptom of 10 (59%) cases in all renal sarcomas was abdominal mass. The pathological diagnosis was leiomyosarcoma (7 cases), rhabdomyosarcoma (2 cases), malignant fibrous histiocytoma (2 cases), low-differentiated sarcoma (2 cases), chromophobe renal cell carcinoma coexisting with liposarcoma (1 case), fibrosarcoma (1 case), embryonic sarcoma (1 case) and leiomyosarcoma (1 case). One patient died of tumor thrombus of the inferior vena cava during surgery. Finally, 15 cases were regularly followed up for 4 to 60 months. Till now, 1 had tumor-free survival for 9 months, and the other 14 cases died 2-38 months after the operation with a median survival time of 18 (range, 5-60) months. The median survival time of leiomyosarcoma group was 28 (range, 11-60) months, and 2 cases of malignant fibrous histiocytoma died 4 and 8 months after the operation respectively.

CONCLUSIONS

The primary renal sarcoma has the clinical symptom similar with advanced renal cell carcinoma and has poor prognosis. Leiomyosarcoma might have relative good prognosis.

Imaging in renal cell carcinoma

Imaging plays a central role in the detection, diagnosis, staging, and follow-up of renal cell carcinoma (RCC). Most renal masses are incidentally detected with modern, high-resolution imaging techniques and a variety of management options exist for the renal masses encountered today. This article discusses the role of multiple imaging modalities in the diagnosis of RCC and the imaging features of specific pathologic subtypes and staging techniques. Future directions in RCC imaging are presented, including dynamic contrast-enhanced and unenhanced techniques, as well as the development of novel tracers for positron emission tomography.

Incidental finding of renal masses at unenhanced CT: prevalence and analysis of features for guiding management

OBJECTIVE

The purposes of this study were to investigate the frequency and clinical relevance of the incidental finding of renal masses at low-dose unenhanced CT and to analyze the results for features that can be used to guide evaluation.

MATERIALS AND METHODS

Images from unenhanced CT colonographic examinations of 3001 consecutively registered adults without symptoms (1667 women, 1334 men; mean age, 57 years) were retrospectively reviewed for the presence of cystic and solid renal masses 1 cm in diameter or larger. An index mass, that is, the most complex or concerning, in each patient was assessed for size, mean attenuation, and morphologic features. Masses containing fat or with attenuation less than 20 HU or greater than 70 HU were considered benign if they did not contain thickened walls or septations, three or more septations, mural nodules, or thick calcifications. Masses with attenuation between 20 and 70 HU or any of these features were considered indeterminate. The performance of CT colonography in the detection of renal cell carcinoma was calculated for masses with 2 or more years of follow-up.

RESULTS

At least one renal mass was identified in 433 (14.4%) patients. The mean size of the index masses was 25 ± 16 mm; 376 (86.8%) masses were classified as benign and 57 (13.2%) as indeterminate. The 20- to 70-HU attenuation criterion alone was used for classification of 53 indeterminate lesions. Follow-up data (mean follow-up period, 4.4 years; range, 2-6.3 years) were available for 353 (81.5%) patients with masses (41 indeterminate, 312 benign). Four of the 41 indeterminate masses were diagnosed as renal cell carcinoma. The sensitivity and specificity for renal cell carcinoma on the basis of the indeterminate criteria were 100% and 89.4%. The positive and negative predictive values were 9.8% and 100%.

CONCLUSION

The incidental finding of a renal mass is relatively common at unenhanced CT, but imaging criteria can be used for reliable identification of most of these lesions as benign without further workup. Mean attenuation alone appears reliable for determining which renal masses need further evaluation.

Primary renal lymphoma mimicking renal cell carcinoma

Primary renal lymphoma is very rare. Lymphomatous involvement of the kidney is often seen as a part of disseminated disease. The prognosis is usually poor with median survival less than a year. It is essential to differentiate between renal cell carcinoma and renal lymphoma in patients presenting with solitary renal masses. We present a 52-year-old lady who presented with a solitary renal mass and was diagnosed to have primary lymphoma of the kidney and discuss briefly about primary renal lymphoma.

A rare presentation of metastatic renal clear cell carcinoma to the tongue seen on FDG PET

Renal clear cell carcinoma has a great metastatic potential, with possibly uncommon secondary lesions, notably in the head and neck region. The role of F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG PET) in the staging or follow-up of urological malignancies is still not clearly defined. We report a case of metastatic renal cell carcinoma involving the tongue and a cervical lymph node, 3 years after initial nephrectomy. The use of combined positron emission tomography/computed tomography scan showed increased F-18 FDG activity in these 2 lesions that were then diagnosed and treated by surgery. Although the diagnostic performance of F-18 FDG PET is limited in the detection of primary disease, this imaging modality can be a very useful tool in the follow-up of renal clear cell carcinoma.

Radiologic evaluation of small renal masses (II): posttreatment management

The increase in the detection of small renal masses (SRMs) and their best knowledge leads to a change in the therapeutic management of these lesions. The use of a less aggressive surgical technique or even an expectant attitude is the current tendency, in order to preserve as much renal function as possible. Imaging techniques are essential in the followup of these lesions. It allows us to know the postsurgical changes and possible complications due to treatment and the presence of local recurrence and metastases. Furthermore, a close radiological followup of SRM related to ablative treatments is mandatory. The purpose of this article is to reveal the imaging features of complications due to surgical or ablative treatments, local recurrence and metastasis, as well as their followup.