Cystic renal cell carcinoma: biology and clinical behavior

CT-based radiomics model using stability selection for predicting the World Health Organization/International Society of Urological Pathology grade of clear cell renal cell carcinoma

OBJECTIVES

This study aimed to develop a model to predict World Health Organization/International Society of Urological Pathology (WHO/ISUP) low-grade or high-grade clear cell renal cell carcinoma (ccRCC) using 3D multiphase enhanced CT radiomics features (RFs).

METHODS

CT data of 138 low-grade and 60 high-grade ccRCC cases were included. RFs were extracted from four CT phases: non-contrast phase (NCP), corticomedullary phase, nephrographic phase, and excretory phase (EP). Models were developed using various combinations of RFs and subjected to cross-validation.

RESULTS

There were 107 RFs extracted from each phase of the CT images. The NCP-EP model had the best overall predictive value (AUC = 0.78), but did not significantly differ from that of the NCP model (AUC = 0.76). By considering the predictive ability of the model, the level of radiation exposure, and model simplicity, the overall best model was the Conventional image and clinical features (CICFs)-NCP model (AUC = 0.77; sensitivity 0.75, specificity 0.69, positive predictive value 0.85, negative predictive value 0.54, accuracy 0.73). The second-best model was the NCP model (AUC = 0.76).

CONCLUSIONS

Combining clinical features with unenhanced CT images of the kidneys seems to be optimal for prediction of WHO/ISUP grade of ccRCC. This noninvasive method may assist in guiding more accurate treatment decisions for ccRCC.

ADVANCES IN KNOWLEDGE

This study innovatively employed stability selection for RFs, enhancing model reliability. The CICFs-NCP model's simplicity and efficacy mark a significant advancement, offering a practical tool for clinical decision-making in ccRCC management.

Clear cell renal cell carcinoma with cystic component similar to multilocular cystic renal neoplasm of low malignant potential: a rare pattern of cyst-dependent progression from multilocular cystic renal neoplasm of low malignant potential

BACKGROUND

For clear cell renal cell carcinoma (ccRCC) with cystic component similar to multilocular cystic renal neoplasm of low malignant potential (MCRN-LMP) and solid low-grade component simultaneously, we propose the designation "ccRCC with cystic component similar to MCRN-LMP" and to study the relationship between MCRN-LMP and it.

METHODS

Twelve cases of MCRN-LMP and 33 cases of ccRCC with cystic component similar to MCRN-LMP were collected from 3,265 consecutive RCCs to compare them in clinicopathological features, immunohistochemical findings (PAX8, CA-IX, CK7, Vimentin, CD10, P504s, TFE3, 34βE12) and prognosis.

RESULTS

There was no significant difference in age, sex ratio, tumor size, treatment, grade and stage between them (P > 0.05). All ccRCCs with cystic component similar to MCRN-LMP coexisted with MCRN-LMP and solid low-grade ccRCCs, and MCRN-LMP component ranged from 20 to 90% (median, 59%). The positive ratio of CK7 and 34βE12 in MCRN-LMPs and ccRCCs' cystic parts was significantly higher than that in ccRCCs' solid parts, but the positive ratio of CD10 in MCRN-LMPs and ccRCCs' cystic parts was significantly lower than that in ccRCCs' solid parts (P < 0.05). There was no significant difference of all immunohistochemistry profiles between MCRN-LMPs and ccRCCs' cystic parts (P > 0.05). No patient developed recurrence or metastasis.

CONCLUSIONS

MCRN-LMP and ccRCC with cystic component similar to MCRN-LMP have similarity and homology in clinicopathological features, immunohistochemical findings and prognosis, and form a low-grade spectrum with indolent or low malignant potential behavior. The ccRCC with cystic component similar to MCRN-LMP may be a rare pattern of cyst-dependent progression from MCRN-LMP.

Malignant ascites following radical nephrectomy for cystic renal cell carcinoma

A 69-year-old man with a history of laparoscopic radical nephrectomy for papillary renal cell carcinoma presented with a 1-week history of generalised abdominal pain, distension and loss of appetite. Clinical examination and CT imaging demonstrated ascites associated with peritoneal nodules, raising the possibility of metastatic disease. Immunochemistry staining from ascites fluid cytology confirmed renal cell carcinoma. Following multidisciplinary discussions, the patient was commenced on a small-molecule tyrosine kinase inhibitor.

Computed Tomography-Guided Microwave Ablation of Cystic Renal Cell Carcinoma: Assessment of Technique and Complications

This report evaluates the techniques and complications of microwave ablation of cystic renal cell carcinoma. Five patients with cystic renal cell carcinoma were treated with microwave ablation between October 2015 and June 2020. Medical records were reviewed to evaluate technique and complications. Technical success and primary technique efficacy both were 100%. There were no complications. Mean follow-up time was 18 months (range, 6-36 months). No local recurrence was identified during the follow-up period. Renal function remained stable at 1 month and the last follow-up. Percutaneous microwave ablation is promising for the nonsurgical management of cystic renal cell carcinoma.

Oncological outcomes of active surveillance and percutaneous cryoablation of small renal masses are similar at intermediate term follow-up

BACKGROUND

Active surveillance (AS) and minimally invasive ablative therapies such as percutaneous cryoablation (PCA) are emerging as alternative treatment modalities in the management of small renal masses (SRMs).

METHODS

Fifty-nine patients underwent PCA since 2011 and 75 underwent AS since 2010 at two different institutions. Only patients with follow-up ≥ 6 months were included. All patients were followed with a standardized protocol. Treatment failure was defined by dimensional progression for AS and renal recurrence for PCA, in addition to stage and/or metastatic progression for both groups.

RESULTS

Treatment failure was observed in 14 cases (18,7%) during AS (mainly due to dimensional progression) and 12 patients (16%) underwent delayed intervention with a mean follow-up of 36,83 months. Seven patients (11,9%) in the PCA group experienced treatment failure with a mean follow-up of 33,39 months and 3 of them underwent re-ablation successfully. Cancer-specific-survival at 2 and 5 years was 100% and 95,8% in AS-group vs. 98,2% and 98,2% in PCA-group (p=0,831). One patient in both groups died from metastatic disease. Overall-survival at 2 and 5 years was 91,7% and 82,4% in the AS-group vs. 96,5% and 96,5% in the PCA-group (p=0,113). Failure-free survival at 2 and 5 years was 90,9% and 70,1% in the AS-group vs. 93,1% and 70,9% in the PCA-group (p=0,645).

CONCLUSIONS

AS and PCA provide similar survival outcomes and are safe and valid treatment options for elderly and comorbid patients with SRMs.

Prolonged natural history of a cystic renal cell carcinoma: A case report

We describe the successful management of a 50-year male who presented with gradually progressive abdominal swelling for over 20 years. The highlights of the case are giant renal mass occupying the whole abdomen and the absence of metastasis despite a long history.

Bosniak Classification of Cystic Renal Masses, Version 2019: An Update Proposal and Needs Assessment

Cystic renal cell carcinoma (RCC) is almost certainly overdiagnosed and overtreated. Efforts to diagnose and treat RCC at a curable stage result in many benign neoplasms and indolent cancers being resected without clear benefit. This is especially true for cystic masses, which compared with solid masses are more likely to be benign and, when malignant, less aggressive. For more than 30 years, the Bosniak classification has been used to stratify the risk of malignancy in cystic renal masses. Although it is widely used and still effective, the classification does not formally incorporate masses identified at MRI or US or masses that are incompletely characterized but are highly likely to be benign, and it is affected by interreader variability and variable reported malignancy rates. The Bosniak classification system cannot fully differentiate aggressive from indolent cancers and results in many benign masses being resected. This proposed update to the Bosniak classification addresses some of these shortcomings. The primary modifications incorporate MRI, establish definitions for previously vague imaging terms, and enable a greater proportion of masses to enter lower-risk classes. Although the update will require validation, it aims to expand the number of cystic masses to which the Bosniak classification can be applied while improving its precision and accuracy for the likelihood of cancer in each class.

Long-term oncological outcomes of cystic renal cell carcinoma according to the Bosniak classification

OBJECTIVES

To evaluate the prognostic role of the Bosniak classification on the long-term oncological outcomes of cystic renal cell carcinomas.

MATERIAL AND METHOD

In a national multicentric retrospective study, we included patients treated surgically for localized cystic RCC from 2000 to 2010. Patients with a follow-up of less than 4 years, benign tumors, and ablative treatments were excluded. The primary outcome was disease-free survival.

RESULTS

152 patients met the inclusion criteria: Bosniak II (6%), III (53%), IV (41%), with a median follow-up of 61 (12-179) months. Characteristics of the population and the tumors were [median, (min-max)] age 57 (25-84) years old, tumor size 43 mm (20-280), RENAL score 7 (4-12), PADUA score 8 (5-14). Treatments were 55% partial nephrectomy, 45% radical nephrectomy, 74% open surgery, and 26% laparoscopy. In pathological report, cystic RCC were mainly of low grade (1-2, 77%) and low stage (pT1, 81%). The two main histological subtypes were conventional (56%) and papillary (23%) RCC. Staging at presentation and histological characteristics were similar between Bosniak III and IV, except for high grade which was more common in Bosniak IV (12 vs 36%, p < 0.01). The Bosniak classification was not predictive of the recurrence, as 5- and 10-year disease-free survival were similar in Bosniak III and IV (92% vs 92% and 84% vs 83%, p = 0.60).

CONCLUSION

The Bosniak classification is predictive of the risk of malignancy but not of the oncological prognosis. Regardless of the initial Bosniak categories, almost all cystic RCCs were of low stage/grade and had low long-term recurrence rate.

Development and prospective validation of a novel weighted quantitative scoring system aimed at predicting the pathological features of cystic renal masses

OBJECTIVES

To develop and prospectively validate a novel weighted quantitative scoring system based on CT findings, namely, the renal cyst index (RCI), aimed at preoperatively predicting the pathological features of cystic renal masses (CRMs).

METHODS

The RCI was based on four critical features of CRMs: the cyst wall, septal, nodule, and cyst contents. These parameters were scored with 1, 2, or 3 points. Weight coefficients for these parameters were determined by the multivariable logistic regression. The odds ratio (OR) and 95% confidence interval (95% CI) were used to summarise the results. The RCI was defined as the sum of these four weight coefficients. Malignancy risk prediction models were built based on the retrospective evaluation of 441 patients. We also compared the prediction ability of the RCI with the Bosniak classification in the 441 patients and applied these novel models to 152 masses resected in our institution to prospectively validate the efficiency of the RCI.

RESULTS

The wall point (OR = 5.71 [95% CI = 1.734-18.808, p = 0.004, point = 2], OR = 12.665 [95% CI = 3.750-42.770, p < 0.001, point = 3]), septal point (OR = 3.325 [95% CI = 1.272-8.692, p = 0.014, point = 3]), nodule point (OR = 4.588 [95% CI = 1.429-14.729, p < 0.001, point = 2], OR = 17.032 [95% CI = 5.017-57.820, p = 0.010, point = 3]), content point (OR = 22.822 [95% CI = 1.041-495.995, p = 0.047, point = 2], OR = 2.723 [95% CI = 1.296-10.696, p = 0.015, point = 3]), and RCI (OR = 1.247 [95% CI = 1.197-1.299, p < 0.001]) were significantly associated with malignancy. Masses with an RCI < 6 were regarded as benign masses; masses with an RCI ≥ 10 were regarded as malignant masses. The malignancy risk of masses with an RCI > 6 but < 10 were determined by a nomogram. The prediction ability of the RCI was significantly superior to the Bosniak classification for Bosniak IIF and III masses (AUC: 0.912 vs. 0.753, p = 0.001). The RCI also accurately predicted the pathological features of 152 masses.

CONCLUSION

The RCI is a reliable quantitative scoring system in predicting the malignancy risk of CRMs, and it outperformed the Bosniak classification system in some ways.

KEY POINTS

• The renal cyst index (RCI) is a useful weighted quantitative classification system based on CT findings for diagnosing cystic renal masses. • The RCI outperforms the Bosniak classification system in some ways, especially for Bosniak IIF and III masses. • Masses with an RCI < 6 can be regarded as a simple cyst, while those with an RCI > 10 can be regarded as malignant masses.

Active Surveillance for Localized Renal Masses: Tumor Growth, Delayed Intervention Rates, and >5-yr Clinical Outcomes

BACKGROUND

Active surveillance (AS) has gained acceptance as a management strategy for localized renal masses.

OBJECTIVE

To review our large single-center experience with AS.

DESIGN, SETTING, AND PARTICIPANTS

From 2000 to 2016, we identified 457 patients with 544 lesions managed with AS from our prospectively maintained kidney cancer database. A subset analysis was performed for patients with ≥5-yr follow-up without delayed intervention (DI).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Linear growth rates (LGRs) were estimated using linear regression for the initial LGR (iLGR) AS interval and the entire AS period. Overall survival (OS) and cumulative incidence of DI were estimated with Kaplan-Meier methods utilizing iLGR groups, adjusting for covariates. DI was evaluated for association with OS in Cox models.

RESULTS AND LIMITATIONS

Median follow-up was 67 mo (interquartile range [IQR] 41-94 mo) for surviving patients. Cumulative incidence of DI (n=153) after 1, 2, 3, 4, and 5 yr was 9%, 22%, 29%, 35%, and 42%, respectively. Median initial maximum tumor dimension was 2.1cm (IQR 1.5-3.1cm). Median iLGR and overall LGR were 1.9 (IQR 0-7) and 1.9 (IQR 0.3-4.2) mm/yr, respectively. Compared with the no growth group, low iLGR (hazard ratio [HR] 1.25, 95% cumulative incidence [CI] 0.82-1.91), moderate iLGR (HR 2.1, 95% CI 1.31-3.36), and high iLGR (HR 1.87, 95% CI 1.23-2.84) were associated with DI (p=0.003). The iLGR was not associated with OS (p=0.8). DI was not associated with OS (HR 1.34, 95% CI 0.79-2.29, p=0.3). Five-year cancer-specific mortality (CSM) was 1.2% (95% CI 0.4-2.8%). Of 99 patients on AS without DI for >5 yr, one patient metastasized.

CONCLUSIONS

At >5 yr, AS±DI is a successful strategy in carefully managed patients. DI often occurs in the first 2-3 yr, becoming less likely over time. Rare metastasis and low CSM rates should reassure physicians that AS is safe in the intermediate to long term.

PATIENT SUMMARY

In this report, we looked at the outcomes of patients with kidney masses who elected to enroll in active surveillance rather than immediate surgery. We found that patients who need surgery are often identified early and those who remain on active surveillance become less likely to need surgery over time. We concluded that active surveillance with or without delayed surgery is a safe practice and that, when properly managed and followed, patients are unlikely to metastasize or die from kidney cancer.

Imaging and Screening of Kidney Cancer

Renal cell carcinoma (RCC) exhibits a diverse and heterogeneous disease spectrum, but insight into its molecular biology has provided an improved understanding of potential risk factors, oncologic behavior, and imaging features. Computed tomography (CT) and MR imaging may allow the identification and preoperative subtyping of RCC and assessment of a response to various therapies. Active surveillance is a viable management option in some patients and has provided further insight into the natural history of RCC, including the favorable prognosis of cystic neoplasms. This article reviews CT and MR imaging in RCC and the role of screening in selected high-risk populations.

Postoperative Outcome of Cystic Renal Cell Carcinoma Defined on Preoperative Imaging: A Retrospective Study

PURPOSE

We evaluated the postoperative outcome of cystic renal cell carcinoma defined on preoperative computerized tomography. We also sought to find the optimal cutoff of the cystic proportion in association with patient prognosis.

MATERIAL AND METHODS

In this institutional review board approved study with waiver of informed consent, 1,315 patients were enrolled who underwent surgery for a single renal cell carcinoma with preoperative computerized tomography. The cystic proportion of renal cell carcinoma was determined on computerized tomography. The optimal cutoff of the cystic proportion was explored regarding cancer specific survival. Renal cell carcinomas were categorized as cystic or noncystic renal cell carcinoma according to a conventional cutoff (ie cystic proportion 75% or greater) and an optimal cutoff. Postoperative outcomes were then compared between the 2 groups. Multivariate Cox regression analysis was performed to determine the independent predictor of cancer specific survival.

RESULTS

Of the 1,315 lesions 107 (8.1%) were identified as cystic renal cell carcinoma according to a conventional cutoff. The postoperative outcome of cystic renal cell carcinoma was significantly better than that of noncystic renal cell carcinoma (p <0.001). Neither metastasis nor recurrence developed after surgery in patients with cystic renal cell carcinoma. In association with the cancer specific survival rate, the optimal cutoff of the cystic proportion was 45% and 197 cases (15.0%) were accordingly defined as cystic renal cell carcinoma. On Cox regression analysis, a cystic proportion of 45% or greater of the renal cell carcinoma was an independent predictor of a favorable outcome regarding cancer specific survival (HR 0.34, p = 0.03).

CONCLUSIONS

Cystic renal cell carcinoma defined on preoperative computerized tomography is associated with low metastatic potential and favorable outcomes after surgery. Particularly, a cystic proportion of 45% or greater is an independent prognostic factor for favorable survival.

Multilocular cystic renal cell carcinoma in a 23 year old female

Multilocular cystic renal cell carcinoma (MCRCC) has been identified as a separate subtype of renal cell carcinoma (RCC) in the 2004 World Health Organization classification of adult renal tumors. MCRCC represents a rare variant of clear cell RCC. The common age group for this tumor is between 40 and 60 years. In our case, MCRCC occurred at the age of 23 years in a female patient. We report this case because of its rarity in this age group, sex, good prognosis, and also to avoid a misdiagnosis as conventional clear cell RCC. However, before making a diagnosis of MCRCC, it has to be differentiated from tubulocystic carcinoma, cystic nephroma, cystic clear cell carcinoma, and clear cell papillary RCC.

Cystic renal masses

PURPOSE

The purpose of the study is to provide an update on the imaging evaluation of cystic renal masses, to review benign and malignant etiologies of cystic renal masses, and to review current controversies and future directions in the management of these lesions.

CONCLUSIONS

Cystic renal masses are relatively common in daily practice. The Bosniak classification is a time-proven method for the imaging classification and management of these lesions. Knowledge of the pathognomonic features of certain benign Bosniak 2F/3 lesions is important to avoid surgery on these lesions (e.g., localized cystic disease, renal abscess). For traditionally surgical Bosniak lesions (Classes 3 and 4), there are evolving data that risk stratification based on patient demographics, imaging size, and appearance may allow for expanded management options including tailored surveillance or ablation, along with the traditional surgical approach.

Sorting the Alphabet Soup of Renal Pathology: A Review

Diseases of the kidney often have their names shortened, creating an arcane set of acronyms which can be confusing to both radiologists and clinicians. This review of renal pathology aims to explain some of the most commonly used acronyms within the field. For each entity, a summary of the clinical features, pathophysiology, and radiological findings is included to aid in the understanding and differentiation of these entities. Discussed topics include acute cortical necrosis, autosomal dominant polycystic kidney disease, angiomyolipoma, autosomal recessive polycystic kidney disease, acute tubular necrosis, localized cystic renal disease, multicystic dysplastic kidney, multilocular cystic nephroma, multilocular cystic renal cell carcinoma, medullary sponge kidney, paroxysmal nocturnal hemoglobinuria, renal papillary necrosis, transitional cell carcinoma, and xanthogranulomatous pyelonephritis.

Cystic renal cell carcinoma carries an excellent prognosis regardless of tumor size

INTRODUCTION

Cystic renal cell carcinoma (cystic RCC) is thought to carry an improved prognosis relative to clear cell RCC (CCRCC); however, this is based on small case series. We used a population-based tumor registry to compare clinicopathologic features and cancer-specific mortality (CSM) of cystic RCC with those of CCRCC.

MATERIALS AND METHODS

The Surveillance, Epidemiology, and End Results database was queried for all patients diagnosed and treated for cystic RCC and CCRCC between 2001 and 2010. Clinical and pathologic factors were compared using t tests and chi-square tests as appropriate. Kaplan-Meier survival analysis compared CSM differences between cystic RCC and CCRCC.

RESULTS

A total of 678 patients with cystic RCC and 46,677 with CCRCC were identified. The mean follow-up duration was 52 and 40 months, respectively. When compared with CCRCC patients, those with cystic RCC were younger (mean age 58 vs. 61 y, P < 0.001), more commonly black (22% vs. 9%, P < 0.001), and female (45% vs. 41%, P = 0.02). Cystic RCCs were more commonly T1a tumors (66% vs. 55%, P < 0.001), well differentiated (33% vs. 16%, P < 0.001), and smaller (mean size = 3.8 vs. 4.5 cm, P < 0.001). Cystic RCC was associated with a reduction in CSM when compared with CCRCC (P = 0.002). In a subset analysis, this reduction in CSM was seen only for those with T1b/T2 tumors (P = 0.01) but not for those with T1a RCCs lesions (P = 0.31).

CONCLUSIONS

We report the largest series of cystic RCC and corroborate the findings of improved CSM when compared with CCRCC for larger tumors; however, no difference was noted in smaller tumors, suggesting that tumor biology becomes more relevant to prognosis with increasing size. These data may suggest a role for active surveillance in appropriately selected patients with small, cystic renal masses.

An Unusual Presentation of Cystic Nephroma in an Adult Man

Cystic nephroma (CN) is an uncommon, benign lesion of the kidney, whose clinical presentation is nonspecific with symptoms such as flack pain, hematuria and urinary tract infection. There are two peaks in the incidence of the tumor, with a bimodal distribution presenting in children between three months and two years, and in adults over 30-years of age. We report a case of CN in the middle part of the left kidney in a 66-year-old male that presented with a singular unilocular, well-circumscribed cyst containing numerous calcifications on the walls and with unremarkable thin or relatively thicker septa from the border with the renal parenchyma, but no solid components. Laparoscopic nephrectomy was performed. Images, histopathological and immunohistochemical features, that are potentially useful for refining this lesion, are discussed.

Microsimulation model of CT versus MRI surveillance of Bosniak IIF renal cystic lesions: should effects of radiation exposure affect selection of imaging strategy?

OBJECTIVE

The objective of this study was to quantify the effects of radiation-induced cancer risks in patients with Bosniak category IIF lesions undergoing CT versus MRI surveillance.

MATERIALS AND METHODS

We developed a Markov-Monte Carlo model to determine life expectancy losses attributable to radiation-induced cancers in hypothetical patients undergoing CT versus MRI surveillance of Bosniak IIF lesions. Our model tracked hypothetical patients as they underwent imaging surveillance for up to 5 years, accounting for potential lesion progression and treatment. Estimates of radiation-induced cancer mortality were generated using a published organ-specific radiation-risk model based on Biological Effects of Ionizing Radiation VII methods. The model also incorporated surgical mortality and renal cancer-specific mortality. Our primary outcome was life expectancy loss attributable to radiation-induced cancers. A sensitivity analysis was performed to assess the stability of the results with variability in key parameters.

RESULTS

The mean number of examinations per patient was 6.3. In the base case, assuming 13 mSv per multiphase CT examination, 64-year-old men experienced an average life expectancy decrease of 5.5 days attributable to radiation-induced cancers from CT; 64-year-old women experienced a corresponding life expectancy loss of 6.9 days. The results were most sensitive to patient age: Life expectancy loss attributable to radiation-induced cancers increased to 21.6 days in 20-year-old women and 20.0 days in 20-year-old men. Varied assumptions of each modality's (CT vs MRI) depiction of lesion complexity also impacted life expectancy losses.

CONCLUSION

Microsimulation modeling shows that radiation-induced cancer risks from CT surveillance for Bosniak IIF lesions minimally affect life expectancy. However, as progressively younger patients are considered, increasing radiation risks merit stronger consideration of MRI surveillance.

Tumor grade of clear cell renal cell carcinoma assessed by contrast-enhanced computed tomography

The purpose of this study was to clarify the association between CT findings and Fuhrman grade of clear cell renal cell carcinoma (ccRCC). The study group consisted of 214 surgically proven ccRCC in 214 patients. Contrast-enhanced CT studies were retrospectively assessed for tumor size, cystic versus solid, calcification, heterogeneity of lesions, percentage of non-enhancing (necrotic) areas, and growth pattern. CT findings and Fuhrman grade were compared. Nineteen of 22 (86.4%) cystic ccRCC were low grade (Fuhrman grades 1-2). There was no significant correlation between tumor size and grade in cystic ccRCC (P = 0.43). In predominantly solid ccRCC, there was significant correlation between tumor size and grade (P < 0.0001). Thirty-eight of 43 (88.4%) infiltrative ccRCC were high grade (Fuhrman grades 3-4). Logistic regression showed tumor size and infiltrative growth were significantly associated with grades 3-4 (P = 0.00083 and P = 0.0059). Cystic ccRCC tends to be low grade. Infiltrative growth and larger tumor size may increase the likelihood of high grade ccRCC.

Laparoscopic versus Open Partial Nephrectomy for Multilocular Cystic Renal Cell Carcinoma: A Direct Comparison Based on Single-Center Experience

Objectives: To compare the treatment of laparoscopic (LPN) versus open partial nephrectomy (OPN) in patients with multilocular cystic renal cell carcinoma (MCRCC). Methods: Thirty-seven patients diagnosed with MCRCC were reviewed retrospectively between January 2007 and January 2013 at our institution. They were divided into two groups: group 1 (LPN) consisted of 19 patients (51.4%) and group 2 (OPN) of 18 patients (48.6%). RENAL and the Preoperative Aspects and Dimensions Used for an Anatomical classification were applied to predict perioperative complications, which were graded based on the Clavien-Dindo classification. Results: The two groups were comparable with regard to all of the patients' baseline characteristics. In group 1, the mean operative time was 142.1 min, including the mean warm ischemia time (WIT) of 32.6 min; the mean estimated blood loss (EBL) was 96.1 ml, the mean retroperitoneal drainage lasted 3.6 days, and the mean postoperative hospital stay was 5.3 days. In group 2, the figures were 126.6 and 23.5 min, 223.3 ml, and 4.6 and 8.7 days, respectively. The differences in WIT, EBL, drainage days and hospitalization were statistically significant between both groups (p < 0.05). No recurrence or new lesions occurred in these patients during a mean follow-up of 37.8 months. Conclusions: Our single-center experience suggests that although it remains technically complex, demanding and challenging for MCRCC, LPN can still induce favorable perioperative results and survival rates in MCRCC are comparable with OPN.

Solid renal masses: what the numbers tell us

OBJECTIVE

Solid renal masses are most often incidentally detected at imaging as small (≤ 4 cm) localized lesions. These lesions comprise a wide spectrum of benign and malignant histologic subtypes, but are largely treated with surgical resection given the limited ability of imaging to differentiate among them with consistency and high accuracy. Numerous studies have thus examined the ability of CT and MRI techniques to separate benign lesions from malignancies and to predict renal cancer histologic grade and subtype. This article synthesizes the evidence regarding renal mass characterization at CT and MRI, provides diagnostic algorithms for evidence-based practice, and highlights areas of further research needed to drive imaging-based management of renal masses.

CONCLUSION

Despite extensive study of morphologic and quantitative criteria at conventional imaging, no CT or MRI techniques can reliably distinguish solid benign tumors, such as oncocytoma and lipid-poor angiomyolipoma, from malignant renal tumors. Larger studies are required to validate recently developed techniques, such as diffusion-weighted imaging. Evidence-based practice includes MRI to assess renal lesions in situations where CT is limited and to help guide management in patients who are considered borderline surgical candidates.

Pathological characteristics and radiographic correlates of complex renal cysts

OBJECTIVES

To characterize pathological and cancer-specific outcomes of surgically resected cystic renal tumors and to identify clinical or radiographic features associated with these outcomes.

METHODS AND MATERIALS

All patients at our institution who underwent radical or partial nephrectomy for complex renal cystic masses between 2004 and 2011 with available computed tomographic imaging were included. The Bosniak score was determined, as were 10 specific radiographic characteristics of renal cysts in patients with preoperative imaging available for review. These characteristics were correlated with cystic mass histopathology. Recurrence-free survival after surgery was determined.

RESULTS

Overall, 133 patients underwent renal surgery for complex cystic lesions, 89 (67%) of whom had malignant lesions. Malignancy risk increased with Bosniak score (P≤0.01) and presence of mural nodules (P = 0.01). Most (63%) malignancies demonstrated clear cell histology. The papillary renal cell carcinomas (25%) exhibited lower enhancement levels (P = 0.04) and were less often septated (P<0.01). Of the malignancies, 79% were low stage (pT1), and 73% were Fuhrman grade 1 or 2. Large cyst size was associated with advanced tumor stage (P = 0.05). Neither Bosniak score nor any other radiographic parameter was associated with Fuhrman grade. In 70 patients with a median follow-up of 43 months, only 1 (1.4%) developed disease recurrence.

CONCLUSIONS

Most cystic renal malignancies are low-stage, low-grade lesions. Papillary renal cell carcinomas account for nearly a quarter of cystic renal malignancies and have unique radiographic characteristics. Disease recurrence after surgical resection is rare. These findings suggest an indolent behavior for cystic renal tumors, and these lesions may be amenable to active surveillance.

Clinicopathologic outcomes of cystic renal cell carcinoma

BACKGROUND

The purpose of this study was to describe the clinicopathologic characteristics and oncologic outcomes of patients who underwent nephrectomy for cystic renal masses.

PATIENTS AND METHODS

Using an institutional review board-approved database, we retrospectively reviewed the clinical, pathologic, radiologic, and oncologic outcome data of patients who received nephrectomy for a complex cystic renal mass.

RESULTS

Sixty-one patients were identified who received nephrectomy for a complex cystic lesion. Average age was 64 years. Thirty-nine (64%) patients were male. At the time of resection, 1 (1.6%), 3 (4.8%), 53 (86.8%), and 4 (6.5%) had a Bosniak category II, IIF, III, and IV cystic lesion, respectively. Nineteen (31.1%) patients were initially managed expectantly but underwent surgery because of progression of complexity on follow-up. Mean pathologic tumor size was 3.3 cm (range, 0.7-12 cm). Forty-eight (78.6%) of the lesions were found to be malignant. Thirty-seven (77.1%), 5 (10.4%), 4 (8.3%), and 2 (4.1%) were stage T1a, T1b, T2a, and T3a, respectively. Clear cell was the most common histologic subtype (44%), followed by papillary (21.3%), and unclassified RCC (4.9%). With a mean and median follow-up of 48.4 and 43.0 months, respectively, no patients developed a local or metastatic recurrence. All patients were alive at last follow-up.

CONCLUSION

In our series with moderate follow-up, cystic RCCs do not appear to recur or progress regardless of size, histologic subtype, or grade. These findings suggest the malignant potential of cRCCs is significantly less than solid RCCs. Further investigation is required to determine if cRCCs should be classified and managed independently from solid RCCs.

Laparoscopic partial nephrectomy for multilocular cystic renal cell carcinoma: a potential gold standard treatment with excellent perioperative outcomes

Background

To report on the perioperative outcomes of laparoscopic partial nephrectomy (LPN) for multilocular cystic renal cell carcinoma (MCRCC) and evaluate the feasibility of this minimally invasive technique as a potential gold standard treatment for MCRCC.

Methods

We retrospectively reviewed the database of surgically pathological findings of patients who were diagnosed with MCRCC at Peking University First Hospital and Chinese PLA General Hospital (Beijing, China) between May 2009 and January 2013. A total of 42 patients with an average age of 48.3 years who were treated with LPN were collected. The patients’ perioperative outcomes were reported and analyzed.

Results

All operations were performed successfully without massive hemorrhage or open conversion. None of patients received lymph node dissection or metastasectomy. Two patients required postoperative transfusion with a mean amount of 175 cc packed red blood cells. Only three patients experienced mild postoperative complications. The mean operative time was 2.4 ± 1.2 hours, including the mean warm ischemia time (WIT) of 23.2 ± 5.7 minutes. The mean estimated blood loss was 72.0 ± 49.6 ml. The mean retroperitoneal drainage was 4.4 ± 1.7 days. The mean postoperative hospital stay was 6.1 ± 1.9 days. Pathologically, 40 (95.2%) of the tumors presented as stage pT1abN0M0, while the remaining two (4.8%) presented as stage pT2aN0M0. No recurrences or new lesions occurred in these patients at a mean follow-up time of 30.0 months.

Conclusions

Although the effective option of LPN is not yet the gold standard treatment for conventional renal cell carcinoma, it should be strongly recommended as a potential gold standard treatment for MCRCC due to the benign nature of MCRCC and the excellent perioperative outcomes provided by LPN.

Multilocular cystic renal cell carcinoma: a rare entity with review of literature

Multilocular cystic renal cell carcinoma (MCRCC) represents a rare variant of clear cell renal cell carcinoma (RCC). MCRCC has been recognized as a separate subtype of RCC in the 2004 World Health Organization (WHO) classification of adult renal tumors. MCRCC is diagnosed on the basis of strict histological criteria according to 2004 WHO classification. The chief differentials diagnosis to be considered include cystic nephroma, cystic clear cell carcinoma, clear cell papillary renal cell carcinoma and tubulocystic carcinoma. Only few cases of MCRCC are reported in literature. This case is being highlighted for its rarity and so as to avoid a misdiagnosis as conventional RCC.

Preoperative decision making for renal cell carcinoma: cystic morphology in cross-sectional imaging might predict lower malignant potential

OBJECTIVES

Several histologic studies showed more favorable oncologic outcome for renal cell carcinoma (RCC) with cystic change. However, there is no prognostic tool to judge on cystic RCC preoperatively. We hypothesized, that cystic morphology in cross-sectional imaging predicts lower malignant potential.

MATERIALS AND METHODS

From our prospectively conducted oncologic database, we identified 825 patients who underwent surgery for malignant renal tumors between 2001 and 2010. In 348 cases (42%), adequate imaging was available for an independent review by 2 radiologists. We excluded recurrent and synchronous bilateral RCC, familial syndromes, collecting duct carcinoma, and metastases of other origin. For the resulting 319 patients, we compared clinical, pathologic, and survival outcomes.

RESULTS

Median age was 63 (19-88) years and 220 (69%) patients were male. Median follow-up was 1.7 (0-9.8) years. Of 319 renal masses, 277 (86.8%) were solid and 42 (13.2%) were cystic. In cystic RCC, median tumor diameter was lower (3 cm vs. 4 cm, P = 0.002) and nephron-sparing surgery was more frequent (69% vs. 41.5%, P = 0.002). None of the patients with cystic RCC and 56 (20.2%) with solid RCC had synchronous systemic disease (P = 0.001). The nuclear grade of cystic RCC was more favorable (P = 0.002). Patients with cystic RCC showed better overall (P = 0.049) and cancer-specific survival (P = 0.027). In a multivariate model, only synchronous metastases, positive R status, and greater tumor diameter were independent risk factors (P ≤ 0.03).

CONCLUSIONS

We report the first study to show that cystic morphology in cross-sectional imaging might predict RCC with a lower malignant potential. This insight could allow less invasive treatment strategies in selected patients.

Multilocular cystic renal cell carcinoma: a rare entity

Multilocular cystic renal cell carcinoma (MCRCC) is an uncommon subtype of clear cell renal cell carcinoma that appears to have a favourable prognosis. Literature reports a very low incidence of 1-2% of MCRCC among the renal neoplasms. The first such reported case was in 1957 by Robinson. In 1998, Eble et al suggested following diagnostic criterion for MCRCC: (1) an expansile mass surrounded by a fibrous capsule; (2) interior of tumour entirely composed of cysts and septa with no expansile nodule or solid component confined to more than 10% of entire tumour and (3) septa containing aggregates of clear epithelial cells. We report a case of MCRCC in a 60-year-old male patient who presented with abdominal lump and after suspicion of renal malignancy underwent nephrectomy. The patient was perfectly well till last follow-up of 3 months postoperatively.

Multilocular cystic renal cell carcinoma: clinicopathological features and preoperative prediction using multiphase computed tomography

OBJECTIVE

• To analyse the clinicopathological and radiological features of multilocular cystic renal cell carcinoma (MCRCC) and to determine the preoperative factors differentiating MCRCC from other cystic RCC (CRCC).

PATIENTS AND METHODS

• The medical records of 53 patients with complex cystic renal masses evaluated by multiphase computed tomography (CT), surgically removed and confirmed as sporadic RCC were reviewed. • Of these 53 patients, 23 were classified as having MCRCC and 30 as other CRCCs, defined as RCCs with extensive cystic change or cystic necrosis. • Another 22 patients were treated for complex cystic renal masses presumed to be RCC and diagnosed as having benign cyst.

RESULTS

• Benign cysts and MCRCCs were significantly more likely to be of Bosniak classification III than other CRCCs (77% vs 61% vs 27%, P= 0.001). • The mean Hounsfield unit (HU) during the corticomedullary phase (CMP) was significantly higher in other CRCCs, with HU ≥38 having 83% sensitivity and 80% specificity for predicting other CRCCs. • In a multiple regression model, Bosniak classification and mean HU during CMP were independent factors predictive of other CRCCs. • In the 41 patients with masses >4 cm in diameter, the combination of Bosniak classification IV and HU ≥38 during CMP showed 63% sensitivity, 96% specificity, 91% positive predictive value and 80% negative predictive value, yielding 2% false-positive and 15% false-negative rates.

CONCLUSIONS

• The mean HU during CMP and Bosniak classification can differentiate MCRCC from other CRCCs. • This could help in selecting an appropriate surgical method, such as nephron-sparing surgery, for complex cystic renal masses >4 cm.

Determination of the cutoff value of the proportion of cystic change for prognostic stratification of clear cell renal cell carcinoma

PURPOSE

Cystic renal cell carcinoma has more favorable biology than noncystic renal cell carcinoma. Recently cystic change detected grossly or by low power microscopy was found to be a good prognostic factor for clear cell renal cell carcinoma. We assessed the optimal cutoff value of the proportion of cystic change with prognostic significance for clear cell renal cell carcinoma.

MATERIALS AND METHODS

We identified 223 patients with clear cell renal cell carcinoma who underwent partial or radical nephrectomy between 2001 and 2003. The cystic proportion of the tumor cut surface was calculated objectively and its prognostic significance was evaluated.

RESULTS

The ROC curve showed that a cystic percent of between 6% and 10% was appropriate to detect patients with renal cell carcinoma at low risk for cancer mortality and progression. A cutoff of 6% was adopted as a break point of cystic change for patient stratification. We analyzed the records of 87 patients (39.0%) with tumors with a cystic proportion of greater than 5%, that is 6% or greater. They had significantly lower stage and lower Fuhrman nuclear grade than patients with tumors with a cystic change of 5% or less (each p<0.0001). On multivariate analysis a cystic proportion of more than 5% was a good prognostic indicator of cancer specific and progression-free survival (HR 0.221, p=0.044 and HR 0.214, p=0.004, respectively).

CONCLUSIONS

In patients with clear cell renal cell carcinoma a cystic change comprising more than 5% of the tumor is a good independent predictor of survival.

Predicting growth of solid renal masses under active surveillance

OBJECTIVES

The natural history and growth rates of untreated solid enhancing renal tumors is being defined through active surveillance series. Serial radiographic evaluation of patients who are not surgical candidates or refuse surgical treatment provides an opportunity to characterize the growth of untreated enhancing renal tumors. Here we evaluate factors that may help predict radiographic growth during observation.

MATERIALS AND METHODS

We reviewed our renal cancer database for enhancing renal masses that were radiographically observed for a period of at least 12 months. Variables examined included patient age, gender, lesion size on presentation, radiographic tumor characteristics, duration of active surveillance, linear growth rate, surgical pathology, development of new renal tumors, and stage progression.

RESULTS

One hundred nine patients with 124 sporadic enhancing renal tumors were identified undergoing a period of active surveillance of at least 12 months. Median patient age was 73 years (mean 69.8, range 35-87); 72% (78/109) of patients were males. Median duration of active surveillance was 26 months (mean 33.4, range 12-156). Multifocal disease was present in 9% (10/109) of patients on presentation, accounting for 20% (25/124) of all tumors. Tumor size on presentation was a median of 2.0 cm (mean 2.61, range 0.4-12.0). Overall median tumor growth rate was 0.21 cm/y (mean 0.28, range 1.4-2.47). Observed linear growth rates were independent of patient age, gender, tumor size on presentation, multifocality, and radiographic characteristics (solid versus cystic), P > 0.05. Of the patients initiating a period of active surveillance 36% (39/109) eventually underwent definitive therapy. Malignant pathology was present in 90% (35/39) of patients undergoing treatment. In patients continuing active surveillance [64% (70/109)], 2.9% (2/70) developed de novo renal lesions and 1.4% (1/70) developed metastatic disease.

CONCLUSIONS

Currently, no clinical predictors of tumor growth or disease progression have been identified, although, the risk of developing progressive disease over the short term appears low. Clinical and molecular markers of disease progression are needed prior to offering active surveillance to otherwise acceptable surgical candidates.

Deficiency of FLCN in mouse kidney led to development of polycystic kidneys and renal neoplasia

The Birt–Hogg–Dubé (BHD) disease is a genetic cancer syndrome. The responsible gene, BHD, has been identified by positional cloning and thought to be a novel tumor suppressor gene. BHD mutations cause many types of diseases including renal cell carcinomas, fibrofolliculomas, spontaneous pneumothorax, lung cysts, and colonic polyps/cancers. By combining Gateway Technology with the Ksp-Cre gene knockout system, we have developed a kidney-specific BHD knockout mouse model. BHD^flox/flox/Ksp-Cre mice developed enlarged kidneys characterized by polycystic kidneys, hyperplasia, and cystic renal cell carcinoma. The affected BHD^flox/flox/Ksp-Cre mice died of renal failure at approximate three weeks of age, having blood urea nitrogen levels over tenfold higher than those of BHD ^flox/+/Ksp-Cre and wild-type littermate controls. We further demonstrated that these phenotypes were caused by inactivation of BHD and subsequent activation of the mTOR pathway. Application of rapamycin, which inhibits mTOR activity, to the affected mice led to extended survival and inhibited further progression of cystogenesis. These results provide a correlation of kidney-targeted gene inactivation with renal carcinoma, and they suggest that the BHD product FLCN, functioning as a cyst and tumor suppressor, like other hamartoma syndrome–related proteins such as PTEN, LKB1, and TSC1/2, is a component of the mTOR pathway, constituting a novel FLCN-mTOR signaling branch that regulates cell growth/proliferation.

[The cystic component in the renal cancer: conceptual overiew]

The renal cancer (RC) cystic component is on the radiological tests and could be consolidate with pathological analysis. The concepts "cystic renal cancer" or "cystic renal tumor" contain a group of entities range from cystic grown pattern RCs to pseudocystic tumors as well as cystic renal diseases coinciding with the RC. The CR and the cystic renal diseases have a great variety to sorts of presentations, giving different ways of radiological images, blending solid and cystic areas. Some papers use indiscriminately expression "cystic" without pathologic proof. Just cystic grown pattern RCs and multilocular cystic carcinoma could be named "cystic renal tumors". For de rest, especially over image study, is more suitable to use expressions as "renal tumor of cystic configuration", while pathologic report are available.