Variant Histology in Bladder Cancer—Current Understanding of Pathologic Subtypes

CT and MRI features of sarcomatoid urothelial carcinoma of the bladder and its differential diagnosis with conventional urothelial carcinoma

BACKGROUND

Sarcomatoid urothelial carcinoma (SUC) is a rare and highly malignant form of bladder cancer with a poor prognosis. Currently, there is limited information on the imaging features of bladder SUC and reliable indicators for distinguishing it from conventional urothelial carcinoma (CUC). The objective of our study was to identify the unique imaging characteristics of bladder SUC and determine factors that aid in its differential diagnosis.

MATERIALS AND METHODS

This retrospective study enrolled 22 participants with bladder SUC and 61 participants with CUC. The clinical, pathologic, and CT/MRI data from both groups were recorded, and a comparison was conducted using univariate analysis and multinomial logistic regression for distinguishing SUC from CUC.

RESULTS

The majority of SUCs were located in the trigone of the bladder and exhibited large tumor size, irregular shape, low ADC values, Vesical Imaging-Reporting and Data System (VI-RADS) score ≥ 4, the presence of necrosis, and an invasive nature. Univariate analysis revealed significant differences in terms of tumor location, shape, the maximum long-axis diameter (LAD), the short-axis diameter (SAD), ADC-value, VI-RADS scores, necrosis, extravesical extension (EVE), pelvic peritoneal spread (PPS), and hydronephrosis/ureteral effusion (p < .001 ~ p = .037) between SUCs and CUCs. Multinomial logistic regression found that only SAD (p = .014) and necrosis (p = .003) emerged as independent predictors for differentiating between SUC and CUC. The model based on these two factors achieved an area under curve (AUC) of 0.849 in ROC curve analysis.

CONCLUSION

Bladder SUC demonstrates several distinct imaging features, including a high incidence of trigone involvement, large tumor size, and obvious invasiveness accompanied by necrosis. A bladder tumor with a large SAD and evidence of necrosis is more likely to be SUC rather than CUC.

Metastatic Tropism in Urothelial Carcinoma With Variant Histology: A Comprehensive NCDB Analysis

INTRODUCTION

Bladder cancer (BCa) with variant histology (VH) is notably aggressive and not as well studied as pure urothelial carcinoma (UC). The characteristics of variant BCa in the setting of metastatic disease may contribute to treatment response/resistance and subsequent disease progression. In this study, we sought to assess VH's impact on metastasis sites at presentation in metastatic BCa.

METHODS

The National Cancer Database was queried from 2004 to 2019 to analyze cT1-4 cN0-3 cM1 patients with UC and VH BCa. The primary endpoint was the presence of metastasis to different organs. Binomial multivariable logistic regression was performed to determine the impact of VH on metastatic sites while controlling for multiple variables.

RESULTS

Total 6005 eligible patients diagnosed with either UC or VH were included. Patients with small cell histology, the second most common VH, were more likely to have liver metastasis (OR: 4.335) while less likely to have lung metastases (OR: 0.521). Squamous cell carcinoma decreased the odds of bone metastasis (OR: 0.449). Adenocarcinoma increased the odds of lung metastases (OR: 1.690). Micropapillary VH is less likely to metastasize to the lungs (OR: 0.182) but more likely to spread to nonregional lymph nodes (OR: 2.623). Sarcomatoid subtype did not exhibit a statistically significant variation in the odds ratio for any of the metastatic sites.

CONCLUSION

This study comprehensively analyzes the limited research regarding metastatic BCa and VH. Our analysis underscores each subtype exhibiting heterogeneous metastatic tropism. Importantly, these findings illustrate the role of routine somatic gene expression profiling to guide adequate staging and treatment intensification and to offer a foundation for future studies of VH BCa care.

MRI-based radiomics analysis of bladder cancer: prediction of pathological grade and histological variant

AIM

To develop magnetic resonance imaging (MRI)-based radiomics models for the prediction of the pathological grade and histological variant of bladder cancer.

MATERIALS AND METHODS

A total of 227 patients who underwent bladder MRI and had histopathologically confirmed grades and variants were included retrospectively from January 2017 to March 2022. They were assigned to a training set (n=131) and a testing set (n=96) based on the MRI system. MRI-based radiomics features were extracted from manually segmented volumes of interest from high-b-value DWI images and ADC maps. The radiomics models were trained with all possible pipelines in the training set. One optimal model was selected using the fivefold cross-validation method and verified by the testing set according to the pathological results. Univariate and multivariate analyses were performed to identify the significant clinical and imaging factors for developing clinical-radiomics models.

RESULTS

The radiomics model for grade prediction had area under the curve (AUC) values of 0.784, 0.786, and 0.733 in the training, cross-validation, and testing sets, respectively. The radiomics model for variant prediction had AUC values of 0.748, 0.757, and 0.789 in the training, cross-validation, and testing sets, respectively. The performance of the clinical-radiomics model was significantly improved compared with the radiomics models alone for the total dataset (AUC for grade: 0.846 versus 0.756; AUC for variant: 0.810 versus 0.757, p<0.05).

CONCLUSION

MRI-based radiomics models could be used to predict the pathological grade and histological variants of bladder cancer with relatively good performance.

Fluorodeoxyglucose positron emission tomography (18F-FDG PET)-computed tomography (CT) in the initial staging of bladder cancer: a single institution experience

BACKGROUND

The purpose of this study was to assess the usefulness of fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET)-computed tomography (CT) scan for staging urinary bladder cancer. The study also sought to determine the effect of ¹⁸F-FDG PET/CT on management decisions and its implications for patient care.

METHODS

A total of 133 patients with bladder cancer who had both conventional imaging and ¹⁸F-FDG PET/CT for initial staging were identified. All ¹⁸F-FDG-PET/CT findings were classified as true positive, true negative, false positive, or false negative based on their potential to impact the intent of treatment. The sensitivity, specificity, positive predictive value, and negative predictive value were calculated using the standard definition. Furthermore, the rate of change in therapy intent was determined for the entire sample and for subgroups with non-muscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC) patients.

RESULTS

The overall concordance rate between PET/CT and conventional imaging was around 54%. On conventional images, 18% of patients had localized disease, which was upstaged in 6.8% of cases using ¹⁸F-FDG PET/CT. Pelvic lymph node involvement was detected in 18.8% of cases using conventional imaging, which was downstaged to localized disease in 4.5% of cases using ¹⁸F-FDG PET/CT. While 63.2% of patients had systemic disease on a CT scan, 24.7% of cases were downstaged using PET/CT. Overall, the rate of change in therapy intent was 26.3% for the entire sample, 24.5% for NMIBC subgroup, and 27.3% for MIBC patients.

CONCLUSIONS

The study found that ¹⁸F-FDG PET/CT is an effective and accurate tool for staging bladder cancer in newly diagnosed patients. Approximately one quarter of patients had a change in management intent based on ¹⁸F-FDG PET/CT results. The study suggests that PET/CT should be used as a standard for newly diagnosed patients, but more research is needed to confirm this.

Clinicopathologic analysis of patients undergoing repeat transurethral resection of bladder tumour following an initial diagnosis of urothelial carcinoma with lamina propria invasion and variant/divergent histology

AIMS

A subset of patients with urothelial carcinoma (UCa) and lamina propria (LP) invasion in bladder biopsies/transurethral resections (TURs) are at significant risk for recurrence and have increased rates of progression to UCa with muscularis propria (MP) invasion. The clinicopathologic features of this patient population has not been well characterised in the Pathology literature.

METHODS

We performed a search through our urologic pathology files and expert consult cases of the senior author for bladder biopsies/TURs of UCa with LP invasion and variant/divergent histology from 2014 to 2020. Patients with a prior diagnosis of UCa with MP invasion or upper tract UCa were excluded. Clinicopathologic data were obtained.

RESULTS

Ninety-five patients with at least one biopsy/TUR of UCa with LP invasion and variant/divergent histology were identified. Mean patient age was 72 years (range: 46-92 years) with a male predominance 2.3:1. Initial variant/divergent histologies identified were: glandular (35.8%), squamous (23.2%), micropapillary (20%), clear cell/lipid rich (12.6%), diffuse/signet ring/plasmacytoid (10.5%), nested (9.5%), sarcomatoid (6.3%), poorly differentiated/anaplastic (4.2%), small cell (2.1%), lymphoepithelioma-like (2.1%), osteoclast-like giant cells (1.1%) and tumour giant cells (1.1%). Two or more variant histologies were identified in 18.9% of these cases. The rate of micropapillary UCa was significantly higher in multifocal tumours compared with unifocal tumours (37% vs 7.1%).

CONCLUSIONS

In our cohort of patients undergoing early repeat biopsy/TUR, 75% of patients had persistent UCa. Additionally, almost 25% of patients had a prior diagnosis of UCa without a variant/divergent histology identified. Our findings highlight the critical role of repeat biopsy/TUR especially in a subset of patients who have variant/divergent histology, even in the absence of MP invasion.

Bladder Preservation for Muscle-Invasive Bladder Cancer With Variant Histology

A growing body of evidence has shown bladder-preservation with chemo-radiotherapy achieves comparable survival to Radical Cystectomy (5-year OS 50%-70%) and superior quality of life outcomes for patients with muscle-invasive urothelial carcinoma of the bladder (UC). However, up to 55% of patients harbor variant histology and in this review we aim to clarify the role of bladder-preservation for this group. We first draw the distinction between urothelial carcinoma with divergent differentiation (UCDD) and non-urothelial carcinoma (NUC). UCDD is common, increasing in prevalence, and whilst each subtype may have its own characteristics current evidence suggests comparable outcomes with radical cystectomy and bladder-preservation. Non-urothelial carcinoma is a collection of distinct pathologies each deserving of its own management strategy. However, these tumors are rare, and evidence is generated from retrospective studies with significant inherent bias. Small cell carcinoma of the bladder has good evidence for bladder-preservation; however, other pathologies such as Squamous Cell Carcinoma and Adenocarcinoma are not well supported. We recommend careful multidisciplinary appraisal of the evidence for each subtype and honest patient discussion about the limited evidence before reaching management decisions. As we look to the future molecular-profiling may help better characterize these tumors and aid in treatment selection.

Radical cystectomy for bladder urothelial carcinoma with aggressive variant histology

Purpose: The aim of this study is to report our experience in managing bladder cancer in patients with variant pathology. Methods: Retrospective data collection for all patients managed by radical cystectomy over the last 3 years for a variant pathol-ogy was completed. We specifically included micropapillary and nested variants. Results: Ten patients were identified, with eight having micropapillary carcinoma (MPC) and two having nested vari-ants. Nine patients were male. The median age was 75. The two patients with nested variant were 56 and 62 years old, respec-tively, whereas all patients with MPC were over the age of 70. Upon cystectomy of all micropapillary cases, three patients(37.5%) had positive lymph node invasion and the final patholo-gy was T2 (two patients), T3 (two patients), and T4 (four patients). Barring a grade III complication Clavien-Dindo classi-fication due to wound dehiscence that necessitated secondary surgical closure, there were no specific perioperative complica-tions. Given the urethral invasion, cystourethrectomy was per-formed on the female patient. Within a median 13-month fol-low-up, three patients developed local recurrence, including two urethral and one new lateral pelvic mass. Conclusions: Considering the muscle invasive nature of micropapillary and nested bladder cancer, aggressive surgical management should not be postponed. Moreover, due to notable prevalence of concurrent and/or recurrent urethral involvement, initial urethrectomy or early and frequent postoperative ure-throscopy should be provided. Patients with variant histology bladder cancer may benefit from early radical cystectomy when compared to bladder sparing protocols and prostate sparing cystectomy treatment options. 

Non-muscle-invasive bladder cancer: An overview of potential new treatment options

AIM

This review article summarizes the current clinical practice guidelines around disease definitions and risk stratifications, and the treatment of non-muscle-invasive bladder cancer (NMIBC). Recently completed and ongoing clinical trials of novel and investigational therapies in Bacillus Calmette-Guérin (BCG)-naïve, BCG-recurrent, and BCG-unresponsive patient populations are also described, e.g., those involving immune checkpoint inhibitors, targeted therapies, other chemotherapy regimens, vaccines, and viral- or bacterial-based treatments. Finally, a brief overview of enhanced cystoscopy and drug delivery systems for the diagnosis and treatment of NMIBC is provided.

BACKGROUND

A global shortage of access to BCG is affecting the management of BCG-naïve and BCG-recurrent/unresponsive NMIBC; hence, there is an urgent need to assist patients and urologists to enhance the treatment of this disease.

METHODS

Searches of ClinicalTrials.gov, PubMed, and Google Scholar were conducted. Published guidance and conference proceedings from major congresses were reviewed.

CONCLUSION

Treatment strategies for NMIBC are generally consistent across guidelines. Several novel therapies have demonstrated promising antitumor activity in clinical trials, including in high-risk or BCG-unresponsive disease. The detection, diagnosis, surveillance, and treatment of NMIBC have also been improved through enhanced disease detection.

Accuracy of Transurethral Resection of the Bladder in Detecting Variant Histology of Bladder Cancer Compared with Radical Cystectomy

BACKGROUND

Correct identification of variant histologies (VHs) of bladder cancer (BCa) at transurethral resection of the bladder (TURB) could drive the subsequent treatment.

OBJECTIVE

To evaluate the concordance in detecting VHs between TURB and radical cystectomy (RC) specimens in BCa patients.

DESIGN, SETTING, AND PARTICIPANTS

We retrospectively analyzed 1881 BCa patients who underwent TURB and subsequent RC at seven tertiary care centers between 1980 and 2018. VHs were classified as sarcomatoid, lymphoepithelioma-like, neuroendocrine, squamous, micropapillary, glandular, adenocarcinoma, nested, and other variants.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Concordance between TURB and RC was defined as the ability to achieve histological subtypes at TURB confirmed at RC specimen, and was expressed according to Cohen's kappa coefficient.

RESULTS AND LIMITATIONS

Of the patients, 14.6% and 21% were diagnosed with VH at TURB and RC specimens, respectively. The most common VHs at TURB were squamous, neuroendocrine, and micropapillary carcinoma (5.2%, 1.5%, and 1.5%, respectively). At RC, the most frequent VHs were squamous, micropapillary, and sarcomatoid carcinoma (7.2%, 3.0%, and 2.7%, respectively). The overall concordance in detecting VH was defined as slight concordance (coefficient: 0.18). Moderate concordance was found for neuroendocrine, adenocarcinoma, and squamous carcinoma (coefficient: 0.49, 0.47, and 0.41, respectively). Micropapillary, glandular, and other variants showed slight concordance (coefficient: 0.05, 0.17, and 0.12, respectively), while nested and sarcomatoid carcinoma showed fair concordance (coefficient: 0.32 and 0.26, respectively). Results may be limited by the absence of centralized pathological analysis.

CONCLUSIONS

A non-negligible percentage of patients were diagnosed with VH at both TURB and RC. TURB showed relatively low accuracy, ranging from poor to moderate, in detecting VHs. Our study underlines the need of additional diagnostic tools in order to identify VHs properly at precystectomy time and to improve patient survival outcomes.

PATIENT SUMMARY

In this report, we underlined the low accuracy of transurethral resection of the bladder in detecting variant histologies and the need for additional diagnostic tools.

Diagnostic value of urine cytology in detecting histologic variants of urothelial carcinomas in the urinary bladder: Cytopathologic correlation of 72 cases

BACKGROUND

Precise identification of histologic variants in urothelial carcinoma (UC) is important because some histologic types have a poor prognosis and clinical management varies. Urine cytology is used for bladder cancer screening, but the cytomorphologic features of histologic variants have not been well described. In the current study, we evaluate the effectiveness of urine cytology in detecting histologic variants of UC in the urinary bladder.

METHODS

Seventy-two urine cytology specimens from patients diagnosed with high-grade UCs by radical cystectomy were retrospectively reviewed and correlated with histopathologic findings of subsequent radical cystectomy specimens.

RESULTS

Of 72 total cases, 24 (33%) cases showed six histologic variants in corresponding surgical specimens, including squamous differentiation (13 cases), plasmacytoid variant (3 cases), micropapillary variant (3 cases), sarcomatoid variant (3 cases), giant cell variant (1 case), and glandular differentiation (1 case). Histopathology and cytomorphology were well correlated in 13 cases (54%), with squamous differentiation in 11 of 13 cases (85%), micropapillary features in 1 out of 3 cases (33%), and spindle cell/sarcomatoid features in 1 of 3 cases (33%). Furthermore, mucosal involvement by histologic variants, not amount of histologic variant, was related to high concordance rates between cytology and histology diagnosis.

CONCLUSIONS

The morphologic features of some histologic variants of high-grade UCs, such as squamous differentiation, micropapillary variant, and sarcomatoid variant, are partially reflected on urine cytology. In addition, mucosal involvement by histologic variants was associated with a higher detection rate of histologic variants in urine cytology.

Transurethral needle electrode resection and transurethral holmium laser resection of bladder cancer

Purpose

The aim of the present study was to explore the efficacy and safety of transurethral needle electrode resection and transurethral holmium laser resection of non-muscular invasive bladder cancer (NMIBC).

Patients and methods

In this prospective, case-control study, patients from the Urinary Surgery or Oncology Department who met the inclusion and exclusion criteria received transurethral needle electrode resection (n = 52) or transurethral holmium laser resection (n = 51).

Results

A total of 103 patients with NMIBC were included in the present study, with 68 males and 35 females. Their mean age was 57.3 years. Sixty-two patients had Ta, 15 patients had T1, and 26 patients had Tis. Operative time, intraoperative blood loss, postoperative gross hematuria time, bladder irrigation time, and postoperative hospitalization time were all significantly lower in the transurethral holmium laser resection group than the transurethral needle electrode resection group. After resection, transurethral holmium laser resection significantly decreased the value of HGF, TSH, and TNF-α versus the transurethral needle electrode resection group. The incidence of obturator reflex was significantly lower in the transurethral holmium laser resection group than the transurethral needle electrode resection group. There was no significant difference in disease-free survival rate and progression-free survival rate between the two groups.

Conclusions

Transurethral holmium laser resection has clinical advantages in the treatment of NMIBC.