[Mimickers and diagnostic pitfalls of urinary bladder cancer]. / Nachahmerläsionen/diagnostische Fallstricke des Harnblasenkarzinoms.

Urothelial carcinoma (UC) is by far the most common malignant neoplasm of the urinary bladder; however, there are both benign and malignant changes of the urothelium which morphologically resemble urothelial carcinomas or other carcinomas of the urinary bladder. Thus, these mimickers can cause problems in the histomorphological diagnosis. This article provides an overview of possible mimickers and pitfalls of bladder cancer as well as practical notes on the diagnostic procedure, partly using case studies.

Artificial intelligence for detection of microsatellite instability in colorectal cancer-a multicentric analysis of a pre-screening tool for clinical application.

BACKGROUND: Microsatellite instability (MSI)/mismatch repair deficiency (dMMR) is a key genetic feature which should be tested in every patient with colorectal cancer (CRC) according to medical guidelines. Artificial intelligence (AI) methods can detect MSI/dMMR directly in routine pathology slides, but the test performance has not been systematically investigated with predefined test thresholds. METHOD: We trained and validated AI-based MSI/dMMR detectors and evaluated predefined performance metrics using nine patient cohorts of 8343 patients across different countries and ethnicities. RESULTS: Classifiers achieved clinical-grade performance, yielding an area under the receiver operating curve (AUROC) of up to 0.96 without using any manual annotations. Subsequently, we show that the AI system can be applied as a rule-out test: by using cohort-specific thresholds, on average 52.73% of tumors in each surgical cohort [total number of MSI/dMMR = 1020, microsatellite stable (MSS)/ proficient mismatch repair (pMMR) = 7323 patients] could be identified as MSS/pMMR with a fixed sensitivity at 95%. In an additional cohort of N = 1530 (MSI/dMMR = 211, MSS/pMMR = 1319) endoscopy biopsy samples, the system achieved an AUROC of 0.89, and the cohort-specific threshold ruled out 44.12% of tumors with a fixed sensitivity at 95%. As a more robust alternative to cohort-specific thresholds, we showed that with a fixed threshold of 0.25 for all the cohorts, we can rule-out 25.51% in surgical specimens and 6.10% in biopsies. INTERPRETATION: When applied in a clinical setting, this means that the AI system can rule out MSI/dMMR in a quarter (with global thresholds) or half of all CRC patients (with local fine-tuning), thereby reducing cost and turnaround time for molecular profiling.

[Status of the availability and use of next generation sequencing (NGS) in bladder cancer-a questionnaire within the uropathology working group]. / Status der Verfügbarkeit und Anwendung von "next generation sequencing" (NGS) beim Harnblasenkarzinom ­ eine Umfrage in der Arbeitsgemeinschaft Uropathologie.

BACKGROUND: Technical advancement and availability of high-throughput analysis has advanced molecular subtyping of most cancers. Thus, new possibilities for precision oncology have emerged. AIM: Therefore, we aimed to collect data regarding availability and use of next generation sequencing (NGS) for urothelial cancer within the uropathology working group of the German Society of Pathology. METHODS: We collected data by questionnaires and additionally asked for sequencing results of bladder cancers in the participating institutions. RESULTS: A total of 13 university-affiliated institutes of pathology took part in the survey. All university institutes offer NGS-based molecular panel diagnostics and provide panels covering between 15 and 170 genes. Altogether, only 20 bladder cancers were sequenced in routine diagnostics and for 10 cancers potential targeted treatment options were available. DISCUSSION: So far, despite availability of NGS diagnostics at university institutes of pathology, only few bladder cancer samples have been sequenced. Based on current data from the molecular subtyping of bladder cancers, we recommend a step-by-step protocol with basic immunohistochemistry analysis and subsequent subtype-dependent analyses, e.g., alterations of the fibroblast growth factor receptors (FGFR) or comprehensive gene panel analyses.

[Molecular tumor board in uro-oncology-from a pathologist's view]. / Molekulares Tumorboard Uroonkologie aus pathologischer Sicht.

Besides evidence- and guideline-based tumor therapy, personalized targeted therapies within study settings or individual experimental settings in advanced cancers without further therapeutic options are emerging. A comprehensive molecular analysis of the tumor in a molecular pathology laboratory is important for all targeted therapy approaches. However, the interpretation of the molecular results is crucial and potential therapeutic conclusions can only be drawn by considering the clinical situation and within a setting of oncological experience. Therefore, the molecular results and their potential impact have to be discussed at a molecular tumor board, an interdisciplinary expert team consisting of clinicians, oncologists, (molecular) pathologists, systems physicians, study teams and where required geneticists. If the molecular tumor board decides a targeted therapeutic approach is appropriate, patients should be enrolled in studies or registries with controlled settings and documentation in order to evaluate the therapeutic concepts. Furthermore, molecular-based individual experimental therapies are possible within extreme clinical situations.

The role of beta-catenin mutation and SOX9 expression in sex cord-stromal tumours of the testis.

The WHO classification of testis tumours includes the group of sex cord-stromal tumours. They are divided into several histological types, i.e. Leydig cell (LCT) and Sertoli cell tumours (SCT). Based on the physiological expression of ß-catenin in normal testis/Sertoli cells, it was previously shown that SCT can carry a ß-catenin mutation, causing a nuclear positivity for ß-catenin and cyclin D1. Furthermore, it could be shown that the stabilization of ß-catenin in Sertoli cells causes the loss of the Sertoli cell marker SOX9. We wanted to know whether the stabilization of ß-catenin in sex cord-stromal tumours influences SOX-9 expression and thus could be used in the diagnosis of sex cord-stromal tumours. Therefore, 53 cases of sex cord-stromal tumours and tumour-like lesions were investigated for their immunohistochemical expressions of ß-catenin, cyclin D1 and SOX9. In addition, mutation analyses of the ß-catenin gene (exon 3; CTNNB1) were performed. ß-catenin mutation in SCT results in nuclear ß-catenin and cyclin-D1 expressions on immunohistochemical analysis. The nuclear expression/stabilization of ß-catenin causes the loss of SOX9 in these tumours. In contrast, SOX9 is considerably expressed in non-mutated SCT as well as in Sertoli cells of non-neoplastic testes. In summary, immunohistochemical analyses of ß-catenin and SOX9 are useful to distinguish SCT from other sex cord-stromal tumours of the testis. Furthermore, the presence of SOX9 indicates that the cells of origin may be Sertoli cells.

[Tumorigenesis from a pathological perspective : Tumor spread and epigenetically regulated genes in bladder cancer]. / Tumorgenese aus pathologischer Sicht : Tumorausbreitung und epigenetisch regulierte Gene beim Harnblasenkarzinom.

The article describes the tumorigenesis of bladder cancer from a pathological perspective in three dimensions: morphology, genetics and epigenetics. Field cancerization and tumor cell migration/seeding are the two main hypotheses used for explaining synchronous and metachronous tumors in the urinary tract. By detailed histological mapping of completely embedded cystectomy specimens we found a single tumor focus in nearly 2/3 of the bladders accompanied by surrounding preinvasive carcinoma in situ. We substantiated our findings by studies analyzing TP53 mutations and loss of heterozygosity in various tumor sites. Identical TP53 mutations suggested a clonal relationship of the tumor foci. In situ lineage tracing via cytochrome C oxidase and succinate dehydrogenase enzyme histochemistry and subsequent mitochondrial DNA mutation analysis for definitive evidence of a clonal relationship in bladder tumors remained inconclusive. We found indications for both theories but intraurothelial migration/seeding was more prominent.A further mechanism in tumorigenesis is gene inactivation by epigenetic DNA methylation. We analyzed DNA methylation of various genes, which had previously been found by RNA expression analysis to be downregulated in bladder cancer. Most importantly, epigenetically silenced ITIH5 was associated with early relapse in pT1 high grade tumors and functionally showed an enhanced invasive metastatic phenotype in tumor cells, suggesting a putative tumor suppressive role. Thus, epigenetic gene silencing is an additional mechanism of tumorigenesis especially in tumor progression.

[Non-muscle invasive bladder cancer : Current aspects of diagnostics, local therapy options and the update of the 2016 WHO classification]. / Nichtmuskelinvasives Harnblasenkarzinom : Aktuelles zu Diagnoseverfahren, lokalen Therapieoptionen und zum Update der WHO-Klassifikation 2016.

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.

[Preneoplastic lesions and precursors of urothelial cancer]. / Präneoplastische Läsionen und Vorstufen des Urothelkarzinoms.

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.

[Specific types of bladder cancer]. / Spezifische Typen des Harnblasenkarzinoms.

Bladder cancer shows rare variants and special subtypes with diverse prognostic importance and therefore may necessitate different therapeutic approaches. For pathologists it is important to histologically diagnose and specify such variants. Nested variants of urothelial carcinoma with inconspicuous, well-formed tumor cell nests present with an aggressive course. The plasmacytoid variant, which morphologically resembles plasma cells is associated with a shorter survival time and a high frequency of peritoneal metastasis. Micropapillary urothelial carcinoma with small papillary tumor cell islands within artificial tissue retraction spaces and frequent lymphovascular invasion also has a poor prognosis. Other important rare differential variants listed in the World Health Organization (WHO) classification are microcystic, lymphoepithelioma-like, sarcomatoid, giant cell and undifferentiated urothelial carcinomas. Additionally, there are three special types of bladder cancer: squamous cell carcinoma, adenocarcinoma and small cell neuroendocrine carcinoma of the bladder. These tumors are characterized by pure squamous cell or glandular differentiation and are sometimes less responsive to adjuvant (chemo)therapy. Small cell carcinoma of the bladder mimics the neuroendocrine features of its pulmonary counterpart, shows an aggressive course but is sensitive to (neo-)adjuvant chemotherapy. The morphology and histology of the most important variants and special types are discussed in this review.

[Cytology in uropathological diagnostics]. / Zytologie in der uropathologischen Diagnostik.

Cytology in uropathological diagnostics is mainly performed for oncological purposes. The assessment of malignancy by urothelial cell morphology is therefore decisive; however, cytology is only sensitive enough to detect high-grade tumor cells and the different low-grade tumors cannot be reliably diagnosed. Thus, the four-tier classification system of cytological findings (i.e. negative, atypical cells but significance uncertain, suspicious and positive) refers to high-grade tumor cells only. Furthermore, for valid cytological diagnostics not only the cytological specimen but also clinical information on cystoscopy findings and, if applicable, a biopsy should be evaluated together. In difficult differential diagnostic settings, e.g. differentiation between reactive versus neoplastic atypia or difficult to access lesions in the upper urinary tract, additional fluorescence in situ hybridization of cytological preparations might be helpful. At the moment there are no indications for further immunocytology or additional biomarker tests.

[Squamous cell lesions of the urinary bladder]. / Plattenepitheliale Läsionen der Harnblase.

BACKGROUND: Squamous cell carcinoma (SCC) and transitional carcinoma with squamous differentiation (SCC/TCC) are rare in western countries. Chronic inflammation and irritation of the urothelium are common risk factors for the development of SCC and TCC/SCC. Tumour biology of squamous cell cancer and precancerous squamous lesions is different from transitional cell cancer (TCC). Recent advances in molecular analysis of benign and malignant squamous cell lesions indicate that they are closely associated and might lead to improved bladder cancer subclassification in the future. AIM: At present, the clinical management and therapy of SCC remains challenging, as scientific evidence based on prospective clinical trials is not available. We performed an analysis of available literature on natural history, treatment, and prognosis of SCC, SCC/TCC and metaplastic lesions. Furthermore, recent findings in molecular cancer biology are discussed with a focus on their relevance for SCC carcinogenesis.

[Non-invasive and invasive urothelial tumours: special challenges in uropathological diagnostics]. / Nicht-invasive und invasive Urothelneoplasien : Besondere Herausforderungen in der uropathologischen Diagnostik.

The current 2004 WHO classification of bladder tumors categorizes non-invasive and invasive urothelial neoplasms into prognostically relevant groups according to the histopathological cell morphology and underlying genetic changes. Although many parts of the classification have not been changed dramatically, even small changes have caused uncertainty and scepticism among urologists and pathologists in recent years. The following review article is structured into various challenges for urologists and pathologists and provides an overview of rare but clinically relevant subgroups and diagnostics, interpretation of diagnoses and pathological findings with respect to consequences for the daily clinical routine (extended diagnosis, therapy and prognosis).

[Urine markers with special regard to fluorescent in situ hybridization (FISH)]. / Uringebundene Marker mit besonderer Berücksichtigung der Fluoreszenz-in-situ-Hybridisierung (FISH).

Patient care with noninvasive or minimally invasive methods is appealing for the patient. It has to be assessed in terms of validity to guarantee improvement of patient care. Urine cytology for the detection of tumour cells can be considered a valid method since its specificity and sensitivity is high when high-grade tumour cells are sought. High-grade tumour cells are considered the clinically most relevant finding in urine specimens. Fluorescent in situ hybridization of interphase nuclei on centromeric and gene loci has been optimized for urothelial carcinoma and increases the sensitivity of tumour findings. It also gives a valid chance to adapt the number of cystoscopies in the follow-up of bladder cancer patients more individually.

[Characterisation of DNA methylation biomarkers for bladder cancer]. / Charakterisierung von DNA-Methylierungs-Biomarkern für das Harnblasenkarzinom.

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.

[Current knowledge in molecular pathology of urothelial cancer]. / Stand des Wissens zur molekularen Pathologie des Urothelkarzinoms.

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.