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Urothelial carcinoma of the upper urinary tract (upper tract urothelial carcinoma, UTUC) is less common than bladder carcinoma with nearly identical risk factors and has a poorer prognosis. The standard diagnostic procedure is imaging of the upper urinary tract by computed tomography urography. In cases of diagnostic uncertainty, a diagnostic ureterorenoscopy with biopsy sampling can be performed in addition to urine cytology. Treatment depends primarily on the stage and grading of the tumor. Depending on the extent and localization, organ-preserving treatment or radical nephroureterectomy is indicated. Perioperative systemic treatment in high-risk UTUC can be performed in both neoadjuvant and adjuvant settings, although the current data on neoadjuvant chemo- and immunotherapy do not yet allow standard application. For metastatic disease, a multimodal treatment approach consisting of cisplatin-based or carboplatin-based chemotherapy, immunotherapy, and treatment with enfortumab vedotin can be considered. Salvage surgery, radiotherapy and metastasectomy are available for rare individual cases., (© 2023. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

The new World Health Organization (WHO) classification of urogenital tumors is still primarily based on anatomic location, but is also a hierarchical taxonomic classification without separate chapters for tumors of the upper urinary tract and the urethra. It clarifies aspects regarding grading and noninvasive entities. It consolidates the use of the Paris system for urinary cytology as well as various subtypes/special types of neoplasms, and incorporates general concepts of the 5th edition of the WHO blue book. In addition to mesenchymal tumors, well-differentiated neuroendocrine tumors and neuroendocrine carcinomas are addressed in separate chapters. Papillary non-invasive low- and high-grade carcinomas and carcinoma in situ remain, while dysplasia and urothelial proliferation of unknown malignant potential (UPUMP) are no longer treated as separate entities. Former variants of urothelial carcinoma are now called subtypes and aberrant differentiation and special types are more precisely defined., (© 2023. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Aims: Immune checkpoint inhibitor (ICI) therapy has become a viable treatment strategy in bladder cancer. However, treatment responses vary, and improved biomarkers are needed. Crucially, the characteristics of immune cells remain understudied especially in squamous differentiated bladder cancer (sq-BLCA). Here, we quantitatively analysed the tumour-immune phenotypes of sq-BLCA and correlated them with PD-L1 expression and FGFR3 mutation status., Methods: Tissue microarrays (TMA) of n = 68 non-schistosomiasis associated pure squamous cell carcinoma (SCC) and n = 46 mixed urothelial carcinoma with squamous differentiation (MIX) were subjected to immunohistochemistry for CD3, CD4, CD8, CD56, CD68, CD79A, CD163, Ki67, perforin and chloroacetate esterase staining. Quantitative image evaluation was performed via digital image analysis., Results: Immune infiltration was generally higher in stroma than in tumour regions. B-cells (CD79A) were almost exclusively found in stromal areas (sTILs), T-lymphocytes and macrophages were also present in tumour cell areas (iTILs), while natural killer cells (CD56) were nearly missing in any area. Tumour-immune phenotype distribution differed depending on the immune cell subset, however, hot tumour-immune phenotypes (high density of immune cells in tumour areas) were frequently found for CD8 + T-cells (33%), especially perforin + lymphocytes (52.2%), and CD68 + macrophages (37.6%). Perforin + CD8 lymphocytes predicted improved overall survival in sq-BLCA while high PD-L1 expression (CPS ≥ 10) was significantly associated with higher CD3 + , CD8 + and CD163 + immune cell density and high Ki67 (density) of tumour cells. Furthermore, PD-L1 expression was positively associated with CD3 + /CD4 + , CD3 + /CD8 + and CD68 + /CD163 + hot tumour-immune phenotypes. FGFR3 mutation status was inversely associated with CD8 + , perforin + and CD79A + lymphocyte density., Conclusions: Computer-based image analysis is an efficient tool to analyse immune topographies in squamous bladder cancer. Hot tumour-immune phenotypes with strong PD-L1 expression might pose a promising subgroup for clinically successful ICI therapy in squamous bladder cancer and warrant further investigation., (© 2023. The Author(s).)

Immunohistochemistry is widely used in diagnostic and scientific analysis of urothelial carcinoma. Objective interpretation of staining results is mandatory for accuracy and comparability in diagnostic and therapeutic patient care as well as research.Herein we summarize and explain standardized microscopic evaluation and scoring approaches for immunohistochemical stainings. We focus on commonly used and generally feasible approaches for different cellular compartments and comment on their utility in diagnostics and research practice., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

High-grade non-muscle-invasive bladder cancer (HG NMIBC) patients are at high risk (HR) of progression to muscle-invasion. Bladder-preserving therapies for this patient subgroup are limited, and additional treatments are desirable. Recently, enfortumab vedotin, targeting cancer-associated NECTIN4, has been approved for the treatment of advanced urothelial carcinoma. However, data on the expression of NECTIN4 and its therapeutic potential for HR NMIBC are scarce. Here, NECTIN4 was immunohistochemically analyzed in urothelial HG NMIBC by studying cohorts of carcinoma in situ (CIS)/T1HG (N = 182 samples), HG papillary tumors from mixed-grade lesions (mixed TaHG) (N = 87) and papillary HG tumors without a history of low-grade disease (pure TaHG/T1HG) (N = 98) from overall 225 patients. Moreover, inter-lesional NECTIN4 heterogeneity in multifocal HG NMIBC tumors was determined. A high prevalence of NECTIN4 positivity was noted across HG NMIBC subgroups (91%, N = 367 samples), with 77% of samples showing moderate/strong expression. Heterogenous NECTIN4 levels were observed between HG NMIBC subgroups: non-invasive areas of CIS/T1HG and pure TaHG/T1HG samples showed NECTIN4 positivity in 96% and 99%, with 88% and 83% moderate/strong expressing specimens, respectively, whereas significantly lower NECTIN4 levels were detected in mixed TaHG lesions (72% positivity, 48% of samples with moderate/strong NECTIN4 expression). Moreover, higher NECTIN4 heterogeneity was observed in patients with multifocal mixed TaHG tumors (22% of patients) compared to patients with multifocal CIS/T1HG and pure TaHG/T1HG tumors (9% and 5%). Taken together, NECTIN4-directed antibody-drug conjugates might be promising for the treatment of HR NMIBC patients, especially for those exhibiting CIS/T1HG and pure TaHG/T1HG tumors without a history of low-grade disease., (© 2022. The Author(s).)

Recent findings suggested a benefit of anti-EGFR therapy for basal-like muscle-invasive bladder cancer (MIBC). However, the impact on bladder cancer with substantial squamous differentiation (Sq-BLCA) and especially pure squamous cell carcinoma (SCC) remains unknown. Therefore, we comprehensively characterized pure and mixed Sq-BLCA (n = 125) on genetic and protein expression level, and performed functional pathway and drug-response analyses with cell line models and isolated primary SCC (p-SCC) cells of the human urinary bladder. We identified abundant EGFR expression in 95% of Sq-BLCA without evidence for activating EGFR mutations. Both SCaBER and p-SCC cells were sensitive to EGFR tyrosine kinase inhibitors (TKIs: erlotinib and gefitinib). Combined treatment with anti-EGFR TKIs and varying chemotherapeutics led to a concentration-dependent synergism in SCC cells according to the Chou-Talalay method. In addition, the siRNA knockdown of EGFR impaired SCaBER viability suggesting a putative "Achilles heel" of Sq-BLCA. The observed effects seem Sq-BLCA-specific since non-basal urothelial cancer cells were characterized by poor TKI sensitivity associated with a short-term feedback response potentially attenuating anti-tumor activity. Hence, our findings give further insights into a crucial, Sq-BLCA-specific role of the ERBB signaling pathway proposing improved effectiveness of anti-EGFR based regimens in combination with chemotherapeutics in squamous bladder cancers with wild-type EGFR-overexpression.

BK polyomavirus (BKPyV) causes major complications in solid organ transplant recipients but little is known about its role in the development of urothelial carcinoma (UC) during immunosuppression. Immunohistochemistry (IHC) screening for polyomavirus large T antigen (LTag) was performed in 94 micropapillary UC (MPUC), 480 unselected UC, 199 muscle invasive UC (including 83 UC with variant differentiation), 76 cases of plasmocytoid, nested and large nested UC and 15 posttransplant UC. LTag expressing UC were reevaluated regarding their histomorphological features and characterized by IHC for p53 and HER2, chromogenic in situ hybridization for HER2 and SNaPshot analysis of the TERT promoter and HRAS. Real-time PCR and next generation sequencing (NGS) were performed to search for BKPyV-DNA and for variants in the tumor and viral genomes. We detected five LTag expressing UC which were diagnosed between 2 and 18 years after kidney (n = 4) or heart (n = 1) transplantation. 89 MPUC without history of organ transplantation and overall 755 UC (including cases with variant histology) were LTag negative. Of the five LTag expressing UC, three were MPUC, one showed extensive divergent differentiation with Mullerian type clear cell carcinoma, and one displayed focal villoglandular differentiation. All five tumors had aberrant nuclear p53 expression, 2/5 were HER2-amplified, and 3/5 had TERT promoter mutations. Within the 50 most common cancer related genes altered in UC we detected very few alterations and no TP53 mutations. BKPyV-DNA was present in 5/5 UC, chromosomal integration of the BKPyV genome was detectable in 4/5 UC. Two UC with BKPyV integration showed small deletions in the BKPyV noncoding control region (NCCR). The only UC without detectable BKPyV integration had a high viral load of human herpesvirus 6 (HHV-6). Our results suggest that LTag expression of integrated BKPyV genomes and resulting p53 inactivation lead to aggressive high-grade UC with unusual, often micropapillary morphology.

Aims: Nested variant of urothelial carcinoma (NVUC) is rare, and only a few small series exist. Molecular characteristics and the classifying marker profile as well as therapeutic targets of this specific variant are mostly unknown. The aim of this study was to characterise NVUC at the molecular level in one of the largest cohorts to date. In addition, we applied an immunohistochemical marker panel in order to define the molecular subtype., Methods and Results: Sixty NVUC cases were collected from different departments. TERT promoter mutation analysis was carried out in all samples using SNaPshot analysis. Targeted sequencing of 48 cancer-related genes by next-generation sequencing (NGS) analysis was performed in a subset of 26 cases. Immunohistochemical markers CD44, CK5, CK14, EGFR, p63, FOXA1, GATA3, CD24 and CK20 were used to elucidate the molecular subtype. A total of 62.5% of NVUC cases harboured a mutation of the TERT promoter. Additionally, TP53, JAK3 and CTNNB1 were among the most frequently mutated genes identified by NGS analysis. Subtyping revealed that all NVUC express luminal markers such as CD24, FOXA1, GATA3 and CK20., Conclusions: In summary, NVUC belong to the luminal molecular subtype. Moreover, a subset of NVUC seems to be characterised by mutations of the Wnt and inflammatory pathways, including JAK3 mutations, indicating a different biological background compared to conventional urothelial bladder cancer., (© 2019 The Authors. Histopathology published by John Wiley & Sons Ltd.)

Comprehensive molecular analyses of urothelial bladder cancer (UBC) have defined distinct subtypes with potential therapeutic implications. In this study, we focused on micropapillary urothelial carcinoma (MPUC), an aggressive, histomorphologically defined rare variant. Apart from genetic alterations shared with conventional UBC, alterations of the HER2 gene have been reported in higher frequencies. However, only small cohorts of MPUCs have been analyzed, and the real impact is still unclear. We collected a cohort of 94 MPUCs and immunohistochemically tested HER2, basal (CD44, CK5, EGFR, p63) and luminal (CD24, FOXA1, GATA3, CK20) markers to allocate MPUC to a molecular subtype. Additionally, HER2 amplification status was assigned by chromogenic in situ hybridization. Sanger sequencing of exon 4 and 8 was used to test for HER2 mutations. Kruskal-Wallis test was calculated to compare marker distribution between proportions of the MPUC component. HER2 2+/3+ staining scores were identified in 39.6% of 91 analyzed MPUCs and were not differentially distributed among the proportion of the MPUC component (P = .89). Additionally, CISH analysis revealed 30% of HER2-amplified tumors independently of the MPUC fraction. In 6/90 evaluable MPUCs, a p.S310F HER2 mutation was detected. Overexpression of luminal markers was observed in the majority of MPUC. Our investigations of the largest cohort of analyzed MPUC demonstrate that HER2 overexpression and amplifications are common genetic alterations and identification of overexpressed luminal markers allows subclassification to the luminal subtype. These findings highlight the need of histomorphological recognition of MPUC and analysis of HER2 status and the luminal molecular subtype for potential targeted therapeutic strategies., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The stratification of bladder cancer into luminal and basal tumors has recently been introduced as a novel prognostic system in patient cohorts of muscle-invasive bladder cancer or high-grade papillary carcinomas. Using a representative immunohistochemistry panel, we analyzed luminal and basal marker expression in a large case series (n = 156) of urothelial carcinoma in situ (CIS), a precancerous lesion that frequently progresses to muscle-invasive disease. The majority of CIS cases was characterized by a positivity for luminal markers (aberrant cytokeratin (CK) 20 85% (132/156), GATA3 median Remmele score (score of staining intensity (0-3) multiplied with percentage of positive cells (0-4)): 12, estrogen receptor (ER) β Remmele score > 2: 88% (138/156), human epidermal growth factor receptor 2 (Her2) Dako score 3+ 32% (50/156), Her2 Dako score 2+ 33% (51/156)), and marginal expression of basal markers (CK5/6+ 2% (3/156), CK14+ 1% (2/156)). To further investigate phenotypic stability during disease progression, we compared 48 pairs of CIS and invasive tumors from the same biopsy. A highly significant loss of luminal marker expression (p < 0.001) was observed in the course of progression whereas an increase of basal marker expression (p < 0.01) was noted in the invasive compartment. Importantly, 91% of CIS cases demonstrated a positivity for at least one of the two predictive markers Her2 and ERβ, indicating that the analysis of Her2 and ERβ may help to identify CIS-patient subgroups prone to more efficient targeted treatment strategies. Larger prospective and biomarker-embedded clinical trials are needed to confirm and validate our preliminary findings.

Introduction: Urothelial carcinoma of the bladder is known as one of most common malignant tumors in the urogenital tract. Non-muscle invasive bladder cancer (NMIBC) in particular has a high recurrence rate and results in correspondingly high costs for the public health system., Methods: To improve the recurrence rate and the prognosis of NMIBC the diagnosis, resection technique, adjuvant instillation therapy and exact histopathological classification of tumor lesions are indispensable. This article gives an overview on the current developments in this field., Results: The current European Association of Urology (EAU) guidelines and the preliminary version of the German S3 guidelines on bladder cancer list photodynamic diagnosis (PDD) and narrow band imaging (NBI) as diagnostic procedures for tumors of the bladder. The trend for resection of bladder tumors is towards the use of en bloc resection using various techniques. Furthermore, an update of the WHO classification aims at a better identification and prognosis of the different risk groups of NMIBC., Conclusion: The treatment of NMIBC can only be improved by the combination of optimized diagnosis, precise tumor resection, improved adjuvant intravesical therapy and correct histopathological evaluation of tumors.

As even a mere thickening of the urothelium can harbor genetic changes identical to that of low grade papillary urothelial tumors, it is not always possible to clearly recognize a precursor lesion of urothelial carcinoma by routine histological diagnostics. Complementary immunohistochemical and molecular diagnostic methods assist the recognition of these entities. These methods especially help to identify clinically important genetically unstable cells as the hallmark of carcinoma in situ (CIS). Little is known about the clinical significance of the morphological subtypes of CIS, which range from large cell to micropapillary variants. For a better understanding of special types of bladder cancer (e.g. adenocarcinoma and squamous cell carcinoma), it seems to be important to define the phenotype and the molecular pattern of non-urothelial lesions, such as intestinal metaplasia and squamous metaplasia, better and more precisely.

Histological tumor subtyping, staging, and grading are of utmost importance to stratify patients with bladder cancer for treatment and should be as precise as possible. In the presented study, we investigated the prognostic impact of standard clinicopathological parameters in cystectomy patients and compared embedding of the entire bladder with standard partial embedding via a virtual superimposed approach. The study included 121 cystectomy specimens, which were completely embedded. Clinical and histopathological data of patients were obtained (median follow-up 21.5 months; range 1-67 months). For 88 patients two-dimensional tumor maps (macrophotographs and histology-based maps) were prepared, and embedding of the entire bladder was compared with a virtual standard partial embedding, created by a virtual overlay and data extraction of the tumor maps. Kaplan-Meier plots, Cox regression estimators, Chi-square, and McNemar tests were used. In a multivariate Cox regression model for overall survival, only venous invasion (p = 0.008, HR = 3.35, 95 % CI 1.375-8.161) and organ-confined (pTis-pT2) versus non-organ-confined diseases (pT3-pT4; p = 0.021, HR 2.669, 95 % CI 1.157-6.159) were found significant. Advanced versus standard embedding revealed significant improvement in the detection of carcinoma in situ (50 versus 61, p = 0.003) and lymphatic invasion (18 versus 24, p = 0.041), but no significant advantage in the detection of tumor stage, tumor multifocality, or venous invasion (all p > 0.05). TNM classification, including lymphatic and venous invasion, is of utmost importance to stratify patients with advanced invasive bladder cancer. Histopathological details are detected more reliably by whole organ embedding, but this approach showed no significant benefit in terms of outcome-related parameters (max. tumor stage, venous invasion) in our cohort.

Metabolic components like fatty acids and acyl-Coenzyme A (acyl-CoA) thioesters have been implicated in the pathogenesis of various tumours. The activation of fatty acids to acyl-CoAs is catalysed by long chain acyl-CoA synthetases (ACSLs), and impairment of ACSL expression levels has been associated with tumourigenesis and progression. Since ACSLs have never been investigated in bladder tissues, the study aims to characterize ACSL expression and acyl-CoA synthesis in normal and neoplastic bladder tissues, as well as cell lines. ACSL isoforms 1, 3, 4 and 5 and synthesis of acyl-CoAs were analysed using qRT-PCR, western blot analysis, immunohistochemistry and lipid mass spectrometry. In normal urothelium, expression of ACSL1, 3, 4 and 5, with highest levels of ACSL isoform 5 was found. However, ACSL5 expression was reduced in corresponding neoplastic tissues and urothelial cell lines depending on the grade of cellular differentiation. Anti-ACSL5 immunostainings showed expression in normal urothelium and a gradual loss of ACSL5 protein via pre-invasive lesions to invasive carcinomas. High expression of ACSL5 correlated with increased α-galactosidase activity and positive Uroplakin III staining in tumours. In contrast, synthesis of acyl-CoAs was enhanced in neoplastic bladder tissues compared to normal urothelium, and reflected an increase with respect to cellular differentiation. These results confirm an expression of ACSLs, especially isoform 5, in human urothelium, prove enzymatic/lipidomic changes in bladder cancer tissues, and suggest an involvement of ACSL5 in cellular maturation and/or senescence with possible effects onto induction of tumour formation or progression. Further work may identify responsible pathway alterations, and attempting to re-balance the metabolic equilibrium of the urothelium may offer a further opportunity for tumour treatment and prevention.

Besides worse prognosis of bladder cancer with squamous differentiation (pure squamous cell carcinoma (SCC) or mixed urothelial carcinoma (UC/SCC)), high-grade non-keratinising squamous differentiation is difficult to identify in haematoxylin-eosin stainings. This study aims to validate routine immunohistochemical markers for squamous differentiation in a larger cohort of patients. Tissue microarrays of 89 pure SCCs and mixed UC/SCCs, 66 urothelial carcinomas (UC), precursor lesions and normal urothelium were stained for cytokeratin (CK) 5/6, CK 5/14, CK 7, CK 20 and uroplakin III. Electron microscopy was performed to confirm the differentiation. Pure SCCs displayed staining throughout the epithelium for CK 5/6 (76.6% (36/47)) and CK 5/14 (95.8% (46/48)), focal staining for CK 7 (28.9% (13/45)) and no staining for CK 20 and uroplakin III (both 0% (0/48)). UCs exhibited a basal or diffuse staining for CK 5/6 (30.2% (16/53)) and CK 5/14 (57.1% (32/56)), focal positivity for CK 7 (83.6% (46/55)), CK 20 (50.9% (29/57)) and uroplakin III (21.8% (12/55)). Each marker discriminated SCC and UC significantly (p < 0.01). A third subgroup rarely showed full epithelial staining for CK 5/6 (14.3% (1/7)) and CK 5/14 (28.6% (2/7)), focal staining for CK 7 (85.7% (6/7)) and no staining for CK 20 and uroplakin III (both 0% (0/7)). Electron microscopy could prove both, SCC and UC characteristics, revealing a transient type. A staining pattern with CK 5/6- and CK 5/14-positivity plus CK 20- and uroplakin III-negativity identified squamous differentiation in bladder tumours and revealed a third type of squamous transdifferentiation.

Despite considerable advances in recent years in our understanding of the genetic changes occurring in urinary bladder cancer, similar progress in the field of epigenetics has hitherto been lacking. Increasingly, however, focus has shifted in the direction of aberrant DNA methylation as a result of recent studies showing the direct impact of such promoter hypermethylation on the loss of tumor suppressor gene expression and function, therefore potentially affecting tumor genesis and progression. The purpose of this study is the identification and characterization of new DNA methylation markers in urinary bladder cancer, with the expectation that these markers could then be incorporated in a multi-gene panel for clinical use in early cancer detection. In addition, better understanding of the signalling pathways involved will undoubtedly impact the development of new treatment strategies. Potential candidate genes, including the Wnt antagonist SFRP5 among others, will be validated by different epigenetic techniques using invasive and superficial urothelial cell lines as well as tumor and urine samples from bladder cancer patients.

Results of molecular pathology have supported changes in the 2004 WHO classification of urothelial cancer. Since then new molecular data such as the distribution pattern of the fibroblast growth factor receptor 3 (FGFR3) has further supported the principle of low and high grade entities of urothelial carcinoma. Animal experiments with knockout mice and conditional knockout systems reveal important parallels to humans and results emphasize the cellular context as a trigger for malignancy. One special feature of the urothelium is its high protection of the urothelial cells by members of the retinoblastoma gene family, efficiently inhibiting invasion even in the presence of p53 mutations. In search of the tumor stem cell phenotype the basal cell phenotype is the focus of attention providing a high clonogenic potential. At the same time detailed analysis of the distribution of mutations in the mitochondrial genome within the urothelium will help to gain insight into the spreading of normal cell or tumor cell clones. The overall data in urological oncology provide evidence that diagnostic and prognostic tools for urothelial cancer can only be reached with multiparametric approaches.

Small cell carcinoma of the urinary bladder is a rare entity known as an aggressive tumor. As it is rarely associated with transitional cell carcinoma in situ but more commonly with invasive transitional cell carcinoma, its origin is not well understood. We report a case of small cell carcinoma with coexisting transitional cell carcinoma in situ, where histologic mapping and parallel immunohistochemical and molecular analyses (TP53 mutation analyses, loss of heterozygosity) were performed. Immunohistochemical characterization (synaptophysin, thyroid transcription factor-1, chromogranin A, neuron specific enolase, CD56, CK, CK7, CK20, CD44v6, and p53) emphasized the morphology. Identical point mutations of TP53 were identified in invasive small cell carcinoma and transitional cell carcinoma in situ. No loss of heterozygosity of microsatellite markers D3S3050, D9S303, D9S304, D9S171, D9S775, D9S1748, D9S1751, D17S786, D17S918, and TP53alu was found in either component. We provide, for the first time, molecular evidence for the development of invasive small cell carcinoma out of transitional cell carcinoma in situ.