Frequent somatic CDH1 loss-of-function mutations in plasmacytoid variant bladder cancer

Histologic subtypes of non-muscle invasive bladder cancer

The majority of bladder cancers (BCs) are non-muscle invasive BCs (NMIBCs) and show the morphology of a conventional urothelial carcinoma (UC). Aberrant morphology is rare but can be observed. The classification and characterization of histologic subtypes (HS) in UC in BC have mainly been described in muscle invasive bladder cancer (MIBC). However, the currently used classification is applied for invasive urothelial neoplasm and therefore, also valid for a subset of NMIBC. The standard transurethral diagnostic work-up misses the presence of HS in NMIBC in a considerable percentage of patients and the real prevalence is not known. HS in NMIBC are associated with an aggressive phenotype. Consequently, clinical guidelines categorize HS of NMIBC as "(very) high-risk" tumors and recommend offering radical cystectomy to these patients. Alternative strategies for bladder preservation can only be offered to highly selected patients and ideally within clinical trials. Novel treatment strategies and biomarkers have been established MIBC and NMIBC but have not been comprehensively investigated in the context of HS in NMIBC. Further evaluation prior to implementation into clinical practice is needed.

Pathology focused review of morphologic subtypes and molecular variants of urothelial carcinoma with an emphasis on clinical/treatment relevance

Urothelial carcinoma (UC) has significant morbidity, mortality, and remains the most financially costly carcinoma to manage and treat. This review will cover special morphologic features of UC that may be noted by the pathologist and any subsequent significance in terms of clinical management or treatment considerations as mentioned or recommended in the latest WHO 2022 classification of GU tumors. Many important potentially therapy altering morphologic findings can be consistently identified and reported on routine microscopic examination of hematoxylin and eosin (H&E) stained slides. Furthermore, there has been a rapid advancement of molecular diagnostics and tailored therapies throughout oncology, and we will briefly highlight some of these as they relate to the management of UC. We will actively attempt to limit the discussion of histologic descriptions or pathologic diagnostic criteria of these entities and focus rather on the recognition of their importance/implication for clinicians who must make clinical management decisions based upon these findings. Finally, the importance of open lines of communication with the pathologists who review clinical specimens as well as their practice and reporting methods cannot be overstated.

Molecular profile of bladder cancer progression to clinically aggressive subtypes

Bladder cancer is a histologically and clinically heterogenous disease. Most bladder cancers are urothelial carcinomas, which frequently develop distinct histological subtypes. Several urothelial carcinoma histological subtypes, such as micropapillary, plasmacytoid, small-cell carcinoma and sarcomatoid, show highly aggressive behaviour and pose unique challenges in diagnosis and treatment. Comprehensive genomic characterizations of the urothelial carcinoma subtypes have revealed that they probably arise from a precursor subset of conventional urothelial carcinomas that belong to different molecular subtypes - micropapillary and plasmacytoid subtypes develop along the luminal pathway, whereas small-cell and sarcomatoid subtypes evolve along the basal pathway. The subtypes exhibit distinct genomic alterations, but in most cases their biological properties seem to be primarily determined by specific gene expression profiles, including epithelial-mesenchymal transition, urothelial-to-neural lineage plasticity, and immune infiltration with distinct upregulation of immune regulatory genes. These breakthrough studies have transformed our view of bladder cancer histological subtype biology, generated new hypotheses for therapy and chemoresistance, and facilitated the discovery of new therapeutic targets.

Molecular Pathology of Urothelial Carcinoma

Urothelial carcinoma is characterized by the presence of a wide spectrum of histopathologic features and molecular alterations that contribute to its morphologic and genomic heterogeneity. It typically harbors high rates of somatic mutations with considerable genomic and transcriptional complexity and heterogeneity that is reflective of its varied histomorphologic and clinical features. This review provides an update on the recent advances in the molecular characterization and novel molecular taxonomy of urothelial carcinoma and variant histologies.

Plasmacytoid urothelial carcinoma of the urinary bladder-A clinicopathological and molecular analysis of 52 cases

Plasmacytoid urothelial carcinoma (UC) is a rare histologic subtype of bladder cancer that is associated with an aggressive clinical behavior. We analyzed the clinicopathologic and molecular features of plasmacytoid UC in 52 patients from a single institute. The patients included 44 men and 8 women, with a mean age of 64 years (range, 41-91 years). All bladder cancers were high-grade UC, and plasmacytoid component accounted for a mean of 47% of bladder tumors (range, 5-100%). Distinct gene mutations were found in most plasmacytoid UCs (n = 49); the most common mutations were TP53 (n = 30), followed by TERT (n = 20), and CDH1 (n = 18). Copy number analysis was performed in 34 patients, and 13 of them showed copy number variations. Expression of HER2 was analyzed in 18 patients by immunohistochemistry, and 3 of them showed HER2 overexpression, which was confirmed by fluorescence in situ hybridization analysis. Thirty-two patients died of disease in a median of 15 months (range, 1-45 months). No individual gene mutations were significantly associated with clinical outcome, but mutations in the mammalian target of rapamycin (mTOR) pathway, including PICK3CA and PIK3R1 mutations, were associated with a significantly shorter survival duration (p < 0.05). Plasmacytoid UC is an aggressive histologic subtype that demonstrates frequent somatic gene mutations and CNVs, which may underlie its oncogenesis and progression. Gene mutations of the mTOR pathway are associated with poor outcome in a subset of patients with plasmacytoid UC.

Current Advances in the Management of Nonurothelial Subtypes of Bladder Cancer

Urothelial cancer (UC) is the most common histology seen in bladder tumors. The 2022 WHO classification of urinary tract tumors includes a list of less common subtypes (formerly known as variants) for invasive UC which are considered high-grade tumors. This review summarizes the most recent advances in the management of selected nonurothelial subtypes of bladder cancer: squamous cell carcinoma, small cell carcinoma, sarcomatoid urothelial carcinoma, micropapillary carcinoma, plasmacytoid carcinoma, adenocarcinoma, and urachal carcinoma. The role of neoadjuvant and adjuvant chemotherapy has not been well characterized for most of these histologies, and prospective data are extremely limited. Participation in clinical trials is recommended in advanced disease.

E-cadherin loss drives diffuse-type gastric tumorigenesis via EZH2-mediated reprogramming

Diffuse-type gastric adenocarcinoma (DGAC) is a deadly cancer often diagnosed late and resistant to treatment. While hereditary DGAC is linked to CDH1 mutations, the role of CDH1/E-cadherin inactivation in sporadic DGAC tumorigenesis remains elusive. We discovered CDH1 inactivation in a subset of DGAC patient tumors. Analyzing single-cell transcriptomes in malignant ascites, we identified two DGAC subtypes: DGAC1 (CDH1 loss) and DGAC2 (lacking immune response). DGAC1 displayed distinct molecular signatures, activated DGAC-related pathways, and an abundance of exhausted T cells in ascites. Genetically engineered murine gastric organoids showed that Cdh1 knock-out (KO), KrasG12D, Trp53 KO (EKP) accelerates tumorigenesis with immune evasion compared with KrasG12D, Trp53 KO (KP). We also identified EZH2 as a key mediator promoting CDH1 loss-associated DGAC tumorigenesis. These findings highlight DGAC's molecular diversity and potential for personalized treatment in CDH1-inactivated patients.

Urinary tract cytology showing variant morphology and divergent differentiation

Urothelial carcinoma represents a diverse group of tumours with distinct histologic subtypes, each exhibiting unique cytomorphologic features, architectural growth patterns, and/or well-developed aberrant differentiation. In fact, there are more than 13 subtypes of urothelial carcinoma recognized in the 2022 WHO classification of tumours in the urinary tract. The identification of these subtypes is crucial for an accurate diagnosis of urothelial carcinoma, and many have important clinical implications. Variant/divergent features may coexist with conventional high-grade urothelial carcinoma (HGUC) or present with 100% variant morphology. In urinary tract cytology (UTC), urothelial carcinoma can display divergent differentiation, such as squamous, glandular, or small cell carcinoma differentiation. The use of cell block preparations and immunohistochemistry with available residual urine can enhance diagnostic accuracy. On the other hand, identifying urothelial carcinoma variants, including nested, micropapillary, and plasmacytoid subtypes, poses significant challenges in UTC. Many cases of these variants are only detected retrospectively after variant histology has been established from resection specimens. Moreover, some variants exhibit features inconsistent with the diagnostic criteria for HGUC according to the Paris System for Reporting Urinary Tract Cytology. Nevertheless, the rarity of pure variant morphology and the occurrence of some false negatives for these variant cases are essential to maintain the specificity of UTC overall. This review covers the histology, cytomorphology, and important clinical aspects observed in urothelial carcinoma exhibiting divergent differentiation and various urothelial carcinoma variants detected in UTC.

One Size Fits Some: Approaching Rare Malignancies of the Urinary Tract

OPINION STATEMENT

Urothelial carcinoma is the predominant cancer of the urinary tract but when divergent and subtype histology (non-urothelial) are identified at time of pathologic diagnosis, therapeutic and diagnostic challenges transpire. To this end, pathologic review to confirm any non-urothelial histology is key since these subtypes can often be overlooked. Few prospective trials are dedicated to understanding these non-urothelial histologic types; however, current, and past trials did allow patients with these non-urothelial histologic types to enroll, and inferences can be made about treatment efficacy and survival. Existing treatment regimens for non-urothelial bladder cancers are akin to standard urothelial cancer regimens using surgical approaches for localized disease and platinum-based chemotherapy for advanced disease. The reported clinical trials, that will be discussed, center on non-urothelial histologic types. These studies, albeit limited, provide critical insight into tumor biology and response to standard platinum-based chemotherapy, immune checkpoint inhibitors, and antibody drug conjugates. The inclusion of non-urothelial histologic types will be essential for clinical trials in development to provide further therapeutic advances and provide essential efficacy data.

Molecular characterization of plasmacytoid urothelial carcinoma and the impact on treatment implications

Bladder cancer researchers and clinicians have increasingly viewed tumor biology through the lens of genomic and molecular alterations, drastically improving our knowledge of the underlying disease biology. This understanding has led to significant advances in treatment options that allow implementation of a personalized approach to cancer treatment. Large-scale genomic studies initially focused on the most common forms of bladder cancer. However, as genomic and molecular technologies become more widespread and are applied to less common variant histologies, we are gaining additional insight into the unique molecular and genomic characteristics driving the biology of variant histologies of bladder cancer. In this review, we summarize the current state of knowledge of molecular alterations underlying the distinct tumor biology of plasmacytoid urothelial carcinoma and how these alterations may impact treatment options.

Renal pelvis cancer with initial symptoms of malignant gastric outlet obstruction

Introduction

Gastric outlet obstruction caused by upper tract urothelial carcinoma is rare.

Case presentation

A 78-year-old man presented to the hospital with nausea and vomiting. No hematuria was observed. Computed tomography revealed a tumor in the right renal pelvis and duodenal stenosis. Gastrojejunostomy was performed to treat the symptoms of the gastric outlet obstruction so that the patient could resume oral intake and outpatient chemotherapy. Chemotherapy was unsuccessful, and the patient died 9 months after the gastrojejunostomy. Histological assessment of an autopsy specimen revealed plasmacytoid urothelial carcinoma with direct infiltration of the duodenal wall, which caused the stenosis.

Conclusion

Autopsy revealed a right renal pelvis cancer causing gastric outlet obstruction. Early gastrojejunostomy enabled oral intake and outpatient visits.

Impact of surgical margin and extent of lymphadenectomy on oncologic outcomes in plasmacytoid urothelial carcinoma

OBJECTIVE

Guideline recommendations disagree on template boundaries for pelvic lymph node dissection (PLND) in conventional urothelial carcinoma. Less is known about PLND in variant histology. We aimed to analyze the role of LND in plasmacytoid urothelial carcinoma (PUC).

METHODS

A retrospective review of patients with cTanyNanyM0 PUC who underwent radical cystectomy (RC) with PLND was performed from 2012 to 2022. Lymph node count (LNC) was a surrogate for extent of lymph node dissection and dichotomized based on maximally selected rank statistics. Multivariable cox hazard regression analysis (MVA) for overall survival (OS) corrected for age, perioperative chemotherapy, soft tissue margin status, and stage ≥pT3 and/or pN+ was performed. Disease free survival (DFS) and OS were estimated using Kaplan-Meier (KM) analysis.

RESULTS

Sixty-seven patients with median age of 71, who were 79.1% male were included. Neoadjuvant and adjuvant chemotherapy were administered in 61.2% and 19.4% of patients, respectively. At RC, 70.1% were ≥pT3. Median LNC was 22 (IQR 14-27) with 43.3% of patients being pN+. Calculated optimal-LNC cut point for DFS and OS was 19. Grouping by optimal (≥20) vs. suboptimal-LNC (<20), no significant clinicodemographic differences were found. Optimal-LNC provided improved DFS (P = 0.05) and OS (P = 0.02). Optimal-LNC (HR 0.47, 0.24-0.93 CI 95%, P = 0.03) and negative soft tissue margin (HR 0.38, 0.19-0.76 CI 95%, P = 0.01) was associated with improved OS on MVA. Receipt of perioperative chemotherapy did not improve OS (P = 0.46).

CONCLUSION

In PUC, complete surgical extirpation achieving negative soft tissue margins and removing ≥20 lymph should be prioritized if operative intervention is pursued.

The Many Faces of Urothelial Carcinomas: An Update From Pathology to Clinical Approach and Challenges in Practice

Urothelial carcinoma is a heterogeneous disease with histomorphological and genomic variations throughout the same tumor or between tumors from different patients. It has been shown that most of these histologic and genetic differences have prognostic significance and may have a guiding role in determining the appropriate treatment choice for the patient. Therefore, it is crucial for both the pathologist and the clinician to be conscious of these variations and to consider them in patient management. Recently, a consensus molecular classification has been developed and categorized urothelial carcinomas into 6 subclasses. These molecular subclasses seem to be associated with prognosis and/or response to certain therapeutic approaches like chemotherapy or immune checkpoint inhibitory therapy; however, it has not yet been sufficiently validated and has some limitations for routine application. As is well known, there are therapeutic limitations in locally advanced or metastatic urothelial carcinomas, especially those inappropriate for standard therapy with platinum-based chemotherapy regimens. Emerging new therapeutic approaches and testing for appropriate patient selection for those are discussed in this article.

Precision Medicine in Bladder Cancer: Present Challenges and Future Directions

Bladder cancer (BC) is characterized by significant histopathologic and molecular heterogeneity. The discovery of molecular pathways and knowledge of cellular mechanisms have grown exponentially and may allow for better disease classification, prognostication, and development of novel and more efficacious noninvasive detection and surveillance strategies, as well as selection of therapeutic targets, which can be used in BC, particularly in a neoadjuvant or adjuvant setting. This article outlines recent advances in the molecular pathology of BC with a better understanding and deeper focus on the development and deployment of promising biomarkers and therapeutic avenues that may soon make a transition into the domain of precision medicine and clinical management for patients with BC.

Recent Advances in the Classification of Bladder Cancer - Updates from the 5th Edition of the World Health Organization Classification of the Urinary and Male Genital Tumors

BACKGROUND

The World Health Organization Classification (WHO) of Urinary and Male Genital Tumors has recently been updated to its 5th edition. The new edition presents a comprehensive approach to the classification of urinary and male genital tumors with an incorporation of morphologic, clinical, and genomic data.

OBJECTIVE

This review aims to update the new classification of bladder cancer in the 5th edition and to highlight important changes in nomenclatures, diagnostic criteria, and molecular characterization, as compared to the 4th edition.

METHODS

The pathologic classification of bladder cancer in the 5th edition of WHO Classification of Urinary and Male Genital Tumours was compared to that in the 4th edition. PubMed was searched using key words, including bladder cancer, WHO 1973, WHO 1998, WHO 2004, WHO 2016, histology, pathology, genomics, and molecular classification in the time frame from 1973 to August of 2022. Other relevant papers were also consulted, resulting in the selection of 81 papers as references.

RESULTS

The binary grading of papillary urothelial carcinoma (UC) is practical, but it may be oversimplified and contribute to "grade migration" in recent years. An arbitrary cutoff (5%) has been proposed for bladder cancers with mixed grades. The diagnosis of papillary urothelial neoplasm with low malignant potential has been dramatically reduced in recent years because of overlapping morphology and treatment with low-grade papillary UC. An inverted growth pattern should be distinguished from true (or destructive) stromal invasion in papillary UC. Several methods have been proposed for pT1 tumor substaging, but it is often challenging to substage pT1 tumors in small biopsy specimens. Bladder UC shows a high tendency for divergent differentiation, leading to several distinct histologic subtypes associated with an aggressive clinical behavior. Molecular classification based on the genomic analysis may be a useful tool in the stratification of patients for optimal treatment.

CONCLUSIONS

The 5th edition of WHO Classification of Urinary and Male Genital Tumours has made several significant changes in the classification of bladder cancer. It is important to be aware of these changes and to incorporate them into routine clinical practice.

KDM6A Loss Triggers an Epigenetic Switch That Disrupts Urothelial Differentiation and Drives Cell Proliferation in Bladder Cancer

Disruption of KDM6A, a histone lysine demethylase, is one of the most common somatic alternations in bladder cancer. Insights into how KDM6A mutations affect the epigenetic landscape to promote carcinogenesis could help reveal potential new treatment approaches. Here, we demonstrated that KDM6A loss triggers an epigenetic switch that disrupts urothelial differentiation and induces a neoplastic state characterized by increased cell proliferation. In bladder cancer cells with intact KDM6A, FOXA1 interacted with KDM6A to activate genes instructing urothelial differentiation. KDM6A-deficient cells displayed simultaneous loss of FOXA1 target binding and genome-wide redistribution of the bZIP transcription factor ATF3, which in turn repressed FOXA1-target genes and activated cell-cycle progression genes. Importantly, ATF3 depletion reversed the cell proliferation phenotype induced by KDM6A deficiency. These data establish that KDM6A loss engenders an epigenetic state that drives tumor growth in an ATF3-dependent manner, creating a potentially targetable molecular vulnerability.

SIGNIFICANCE

A gain-of-function epigenetic switch that disrupts differentiation is triggered by inactivating KDM6A mutations in bladder cancer and can serve as a potential target for novel therapies.

Plasmacytoid Variant Urothelial Cell Carcinoma: A Case of a Histological Variant of Urinary Bladder Cancer With Aggressive Behavior

This paper presents a case report of plasmacytoid variant urothelial carcinoma (PVUC), a rare form of transitional cell carcinoma. PVUC is known for its unique clinical features, aggressive behavior, and poor survival rates. PVUC comprises less than 3% of all bladder tumors, and its diagnosis is often difficult due to its resemblance to other forms of bladder cancer. It requires a staging workup to rule out metastasis, relies heavily on immunostaining and histopathological analysis for diagnosis, and requires a multidisciplinary approach with early aggressive treatment, including cisplatin-based chemotherapy following surgery. This report highlights the importance of understanding rare variants of bladder cancer to ensure timely and accurate diagnosis and appropriate treatment planning. We report here a case of a 75-year-old male with multiple comorbidities who presented with hematuria and was diagnosed with urothelial carcinoma plasmacytoid type, which was initially treated with transurethral resection but later found to be unresectable and treated with palliative chemotherapy and radiation therapy. Eventually, the patient passed away three years after the diagnosis.

Urothelial Carcinoma: Divergent Differentiation and Morphologic Subtypes

Urothelial carcinoma (UC) is known to encompass a wide spectrum of morphologic features and molecular alterations. Approximately 15% to 25% of invasive UC exhibits histomorphologic features in the form of "divergent differentiation" along other epithelial lineages, or different "subtypes" of urothelial or sarcomatoid differentiation. It is recommended that the percentage of divergent differentiation and or subtype(s) be reported whenever possible. Recent advances in molecular biology have led to a better understanding of the molecular underpinning of these morphologic variations. In this review, we highlight histologic characteristics of the divergent differentiation and subtypes recognized by the latest version of WHO classification, with updates on their molecular and clinical features.

Molecular Taxonomy and Immune Checkpoint Therapy in Bladder Cancer

Bladder cancer is a heterogeneous disease, which exhibits a wide spectrum of clinical and pathologic features. Recent genomic studies have revealed that distinct molecular alterations may underlie the diverse clinical behaviors of bladder cancer, leading to a novel molecular classification. The intrinsic molecular subtypes exhibit distinct gene expression signatures and different clinicopathologic features. Genomic alterations also underlie the development of bladder cancer histologic subtypes. Genomic characterization provides new insights to understanding the biology of bladder cancer and improves the diagnosis and treatment of this complex disease. Biomarkers can aid the selection of patients for immune checkpoint therapy.

Non-urothelial and urothelial variants of bladder cancer

Non-urothelial bladder cancers make up a rare minority of all genitourinary (GU) tract histologic cancers since urothelial cancer (UC) makes up the most common histologic subtype. Bladder cancer variant histology (BCVH) or urothelial variants also occur rarely though distinction is important given aggressive presentation and natural history. While methods for diagnosis and treatment of typical urothelial cancers (UC) are well-established, there are no clear guidelines with regard to the diagnosis of non-urothelial bladder cancers, which often results in misdiagnosis and treatment delay. This review will focus on the clinicopathologic characteristics of the most common non-urothelial bladder cancers, to be distinguished from bladder cancer variant histology containing a UC component. The role of genomics in non-urothelial bladder cancers is evolving and the use of biomarkers to guide the diagnosis and treatment of these tumors remains a key area of unmet need. Treatment of these cancers will be discussed in a companion review.

LGR6-dependent conditional inactivation of E-cadherin and p53 leads to invasive skin and mammary carcinomas in mice

Tissue-specific inactivation of E-cadherin combined with tumor suppressor loss leads to invasive and metastatic cancers in mice. While epidermal E-cadherin loss in mice induces squamous cell carcinomas, inactivation of E-cadherin in the mammary gland leads to invasive lobular carcinoma. To further explore the carcinogenic consequences of cell-cell adhesion loss in these compartments, we developed a new conditional mouse model inactivating E-cadherin (Cdh1) and p53 (Trp53) simultaneously in cells expressing the leucine-rich repeat-containing G-protein coupled receptor 6 (Lgr6), a putative epithelial stem cell marker in the skin and alveolar progenitor marker in the mammary gland. Compound Lgr6-CreERT2;Cdh1^F;Trp53^F female mice containing either heterozygous or homozygous Cdh1^F alleles were bred, and Lgr6-driven Cre expression was activated in pre-puberal mice using tamoxifen. We observed that 41% of the mice (16/39) developed mostly invasive squamous-type skin carcinomas, but also a non-lobular mammary tumor was formed. In contrast to previous K14cre or WAPcre E-cadherin and p53 compound models, no significant differences were detected in the tumor-free survival of Lgr6-CreERT2 heterozygous Cdh1^F/WT;Trp53^F/F versus homozygous Cdh1^F/F;Trp53^F/F mice (778 versus 754 days, p=0.5). One Cdh1^F homozygous mouse presented with lung metastasis that originated from a non-lobular and ERα negative invasive mammary gland carcinoma with squamous metaplasia. In total, 2/8 (25%) Cdh1^F heterozygous and 3/12 (25%) Cdh1^F homozygous mice developed metastases to lungs, liver, lymph nodes, or the gastro-intestinal tract. In conclusion, we show that inducible and conditional Lgr6-driven inactivation of E-cadherin and p53 in mice causes squamous cell carcinomas of the skin in approximately 40% of the mice and an occasional ductal-type mammary carcinoma after long latency periods.

FOXA1 repression drives lineage plasticity and immune heterogeneity in bladder cancers with squamous differentiation

Cancers arising from the bladder urothelium often exhibit lineage plasticity with regions of urothelial carcinoma adjacent to or admixed with regions of divergent histomorphology, most commonly squamous differentiation. To define the biologic basis for and clinical significance of this morphologic heterogeneity, here we perform integrated genomic analyses of mixed histology bladder cancers with separable regions of urothelial and squamous differentiation. We find that squamous differentiation is a marker of intratumoral genomic and immunologic heterogeneity in patients with bladder cancer and a biomarker of intrinsic immunotherapy resistance. Phylogenetic analysis confirms that in all cases the urothelial and squamous regions are derived from a common shared precursor. Despite the presence of marked genomic heterogeneity between co-existent urothelial and squamous differentiated regions, no recurrent genomic alteration exclusive to the urothelial or squamous morphologies is identified. Rather, lineage plasticity in bladder cancers with squamous differentiation is associated with loss of expression of FOXA1, GATA3, and PPARG, transcription factors critical for maintenance of urothelial cell identity. Of clinical significance, lineage plasticity and PD-L1 expression is coordinately dysregulated via FOXA1, with patients exhibiting morphologic heterogeneity pre-treatment significantly less likely to respond to immune checkpoint inhibitors.

Are We Ready to Implement Molecular Subtyping of Bladder Cancer in Clinical Practice? Part 2: Subtypes and Divergent Differentiation

Following several attempts to achieve a molecular stratification of bladder cancer (BC) over the last decade, a "consensus" classification has been recently developed to provide a common base for the molecular classification of bladder cancer (BC), encompassing a six-cluster scheme with distinct prognostic and predictive characteristics. In order to implement molecular subtyping (MS) as a risk stratification tool in routine practice, immunohistochemistry (IHC) has been explored as a readily accessible, relatively inexpensive, standardized surrogate method, achieving promising results in different clinical settings. The second part of this review deals with the pathological and clinical features of the molecular clusters, both in conventional and divergent urothelial carcinoma, with a focus on the role of IHC-based subtyping.

Panel Informativity Optimizer: An R Package to Improve Cancer Next-Generation Sequencing Panel Informativity

Mutation detection by next-generation sequencing is routinely used for cancer diagnosis. Selecting an optimal set of genes for a given cancer is not trivial as it has to optimize informativity (ie, the number of patients with at least one mutation in the panel), while minimizing panel length to reduce sequencing costs and increase sensitivity. We propose herein Panel Informativity Optimizer (PIO), an open-source software developed as an R package with a user-friendly graphical interface to help optimize cancer next-generation sequencing panel informativity. Using patient-level mutational data from either private data sets or preloaded data set of 91 independent cohorts from 31 different cancer types, PIO selects an optimal set of genomic intervals to maximize informativity and panel size in a given cancer type. Different options are offered, such as the definition of genomic intervals at the gene or exon level and the use of optimization strategy at the patient or patient per kilobase level. PIO can also propose an optimal set of genomic intervals to increase informativity of custom panels. A panel tester function is also available for panel benchmarking. Using public databases, as well as data from real-life settings, we demonstrate that PIO allows panel size reduction of up to 1000 kb, and accurately predicts the performance of custom or commercial panels.

Prognostic Significance of Lineage Diversity in Bladder Cancer Revealed by Single-Cell Sequencing

Bladder cancer is the most common malignant tumor of the urinary system. We investigated the clinical implications of cell lineages in bladder cancer by integrating single-cell and bulk transcriptome data. By investigating the single-cell transcriptional profiles of 12,424 cells from normal bladder, eleven cell types and five types of epithelial sub-population were identified. Based on the signature of cell types identified in single-cell profiles, deconvolution analysis was employed to estimate cell types and epithelial lineages in the bulk RNA sequencing bladder cancer cohort. Cancer subtypes with clinical implications were further identified based on the heterogeneity of the epithelial lineage across patients. This study suggests that the EMT-like subtype is robustly correlated with poor prognosis and the umbrella subtype is a positive factor for the patient survival. Our research has a high potential for accurate prognostic and therapeutic stratification of bladder cancer.

Clinical whole-genome sequencing in cancer diagnosis

Characterizing the genomic landscape of cancers is a routine part of clinical care that began with the discovery of the Philadelphia chromosome and has since coevolved with genomic technologies. Genomic analysis of tumors at the nucleotide level using DNA sequencing has revolutionized the understanding of cancer biology and identified new molecular drivers of disease that have led to therapeutic advances and improved patient outcomes. However, the application of next-generation sequencing in the clinical laboratory has generally been limited until very recently to targeted analysis of selected genes. Recent technological innovations and reductions in sequencing costs are now able to deliver the long-promised goal of tumor whole-genome sequencing as a practical clinical assay.

Prostate Cancer with Peritoneal Carcinomatosis: A robotic-assisted radical prostatectomy-based Case Series

OBJECTIVE

To aid in the diagnosis and treatment of patients with metastatic tumor seeding, an exceedingly phenomenon following minimally invasive urological surgery, additional case reports are needed.

MATERIALS AND METHODS

We report our experience with patients determined to have peritoneal carcinomatosis following robotic-assisted radical prostatectomy (RARP) and provide a descriptive summary of these unique cases.

RESULTS

Five cases of peritoneal carcinomatosis were identified, all of which occurred relatively late - between 8-13 years - following RARP. Four of the five cases had T3 disease at the time of prostatectomy. ⁶⁸Ga-PSMA PET identified peritoneal carcinomatosis in three of five cases.

CONCLUSIONS

Certain clinical factors, such as advanced pathologic stage at the time of prostatectomy, may predict risk for carcinomatosis following RARP. Additionally, next generation imaging modalities, such as PSMA PET, may aid in identifying these metastases and are likely to identify increasing numbers of these patients as next generation imaging becomes more widely available. Continued documentation and classification of this atypical presentation are needed to improve our understanding and management of this phenomenon.

Association between germline pathogenic variants and breast cancer risk in Japanese women: the HERPACC study

Approximately 5-10% of breast cancers are hereditary, caused by germline pathogenic variants (GPVs) in breast cancer predisposition genes. To date, most studies of the prevalence of GPVs and risk of breast cancer for each gene based on cases and non-cancer controls have been conducted in Europe and the United States, and little information from Japanese populations is available. Furthermore, no studies considered confounding by established environmental factors and single nucleotide polymorphisms (SNPs) identified in genome-wide association studies (GWAS) together in GPV evaluation. To evaluate the association between GPVs in nine established breast cancer predisposition genes including BRCA1/2 and breast cancer risk in Japanese women comprehensively, we conducted a case-control study within the Hospital-based Epidemiologic Research Program at Aichi Cancer Center (629 cases and 1153 controls). The associations between GPVs and the risk of breast cancer were assessed by odds ratios (OR) and 95% confidence intervals (CI) using logistic regression models adjusted for potential confounders. A total of 25 GPVs were detected among all cases (4.0%: 95%CI:2.6-5.9), whereas four individuals carried GPVs in all controls (0.4%). OR for breast cancer by all GPVs and by GPVs in BRCA1/2 was 12.2 (4.4-34.0, P = 1.74E-06) and 16.0 (4.2-60.9, P = 5.03E-0.5), respectively. A potential confounding with GPVs was observed for the GWAS-identified SNPs, whereas not for established environmental risk factors. In conclusion, GPVs increase the risk of breast cancer in Japanese women regardless of environmental factors and GWAS-identified SNPs. Future studies investigating interactions with environment and SNPs are warranted.

Patient with prostatic adenocarcinoma with plasmacytoid features and an aberrant immunohistochemical phenotype diagnosed by biopsy and a mini-review of plasmacytoid features in the genitourinary system: A case report

Prostate cancer is one of the most commonly diagnosed malignancies in men. Most of these tumors are adenocarcinomas. Plasmacytoid is a rare variant of adenocarcinoma described by previous studies in the genitourinary system and is characterized by the plasmacytoid appearance of tumor cells with abundant cytoplasm and abnormally placed hyperchromatic nuclei. However, to the best of our knowledge, plasmacytoid adenocarcinoma has rarely been described in the prostate. This report describes a new case of plasmacytoid adenocarcinoma of the prostate diagnosed by biopsy and summarizes the known literature on plasmacytoid features in the genitourinary system. A 62-year-old male patient presented to the hospital with urinary retention, hematuria, weakness and weight loss. The digital rectal examination revealed an irregular enlargement. Laboratory findings showed elevated levels of prostate specific antigen (PSA; 43.6 ng/ml). Transrectal ultrasound showed invasion of the right seminal vesicle. Prostate tumor core biopsies were collected and sent for diagnosis. Histological examination revealed a high-grade prostatic adenocarcinoma Gleason score of 5+5 (total score 10). The tumor cells had a plasmacytoid appearance with abundant cytoplasm and abnormally placed hyperchromatic nuclei. The immunohistochemical phenotype was characterized by abundant positivity for cytokeratin (CK)AE1/AE3 and PSA. By contrast, tumor cells were negative for p63, CK 34BE12 and GATA binding protein 3 (urothelial markers), synaptophysin (neuroendocrine marker). Tumor cells were also negative for E-cadherin, which is particularly indicative of CDH1 alterations. To the best of our knowledge, this is the first description of a plasmacytoid adenocarcinoma of the prostate diagnosed by biopsy, showing an irregular immunophenotype that may indicate somatic CDH1 alterations. The presentation of a novel rare variant of prostatic carcinoma that differs from other neoplasms of the genitourinary system may contribute to an improved understanding of this uncommonly found histological pattern that may also be mandatory due to the clinical and prognostic implications of this diagnosis.

Colonic Adenocarcinoma with Plasmacytoid Feature: Histopathology and Molecular Characteristics of a Rare Neoplasm with an Unusual Presentation

Colorectal carcinoma with noncohesive tumor cells has been described in tumors with signet ring cells (mucinous adenocarcinoma and signet ring cell adenocarcinoma) and rhabdoid feature (carcinoma with sarcomatoid component). Cases of carcinoma with plasmacytoid morphology are rare in the gastrointestinal tract, and a single case of plasmacytoid colorectal carcinoma has been reported. We report the case of a 37-year-old woman who presented with urinary symptoms, hematuria, and abdominal pain. Imaging studies showed segmental sigmoid wall thickening with pericolic infiltration and focal bladder wall thickening. The cystoscopy with transurethral resection of bladder tumor revealed muscle invasion, dis-cohesive carcinoma with plasmacytoid morphology, which was initially misdiagnosed as the plasmacytoid urothelial carcinoma. Immunohistochemical stains showed the tumor cells to be positive for CDX2, CK20, and SATB2 and negative for p63, GATA3, CK7, and Uroplakin II, indicating the colorectal origin of the tumor. The subsequent colonic wall biopsy showed the same tumor. Molecular studies identified BRAF V600E, SMAD4, and p53 mutations associated with aggressive colorectal adenocarcinoma with mucinous/signet ring cell features. Further whole-exome sequencing and whole transcriptome analysis confirmed the colorectal origin of the tumor. This rare colorectal adenocarcinoma with the plasmacytoid feature may represent the signet ring cell adenocarcinoma lacking extracellular mucin or intracellular vacuole. Diagnosis of this rare histological subtype of colorectal carcinoma is important, particularly in the unusual presentation of this aggressive tumor.

Primary Signet Ring Cell/Histiocytoid Carcinoma of the Eyelid: Clinicopathologic Analysis with Evaluation of the E-Cadherin/β-Catenin Complex and Associated Genetic Alterations

Signet Ring Cell (SRC)/Histiocytoid carcinoma of the eyelid is a rare neoplasm that shares histological and immunohistochemical similarities with diffuse gastric cancer and breast lobular carcinoma. The CDH1 gene, which encodes the E-cadherin protein, is the best known gene associated with these tumors. The structural and functional integrity of E-cadherin is regulated by interconnecting molecular pathways which might participate in the development of this disease. Hence, we analyzed the protein expression in key genes in E-cadherin-related pathways associated with primary SRC/Histiocytoid carcinoma of the eyelid. SRC/Histiocytoid carcinoma diagnosed in the eyelid/orbit at MD Anderson Cancer Center from 1990 to 2016 were evaluated. Clinicopathologic findings were studied to confirm the primary site of origin. Immunohistochemical studies for the expression of E-cadherin, β-catenin, c-Myc, Cyclin D1, Src, and p53 were analyzed. Next generation sequencing for the detection of somatic mutations was performed on each tumor with matched normal tissue, examining 50 cancer-related genes. Four primary SRC/Histiocytoid carcinomas of the eyelid were diagnosed in four male patients aged 40-82 years. Immunohistochemically, two tumors with loss of E-cadherin expression had weak β-catenin and low cytoplasmic staining for Src while the other two cases with intact E-cadherin showed strong β-catenin expression and high cytoplasmic expression for Src. Cyclin D1 was focally positive in three cases. Somatic mutations in CDH1, PIK3CA, and TP53 genes were detected in two cases. Our results suggest an abnormality in the convergence of E-cadherin/β-catenin pathways which may promote tumorigenesis by inducing expression of oncogenes such as Cyclin D1 and C-Myc. Mutations in CDH1, PIK3CA, and TP53 genes could induce E-cadherin dysfunction which takes part in the development and progression of this malignancy.

CDKN1A/p21WAF1, RB1, ARID1A, FLG, and HRNR mutation patterns provide insights into urinary tract environmental exposure carcinogenesis and potential treatment strategies

Bladder carcinoma has a 6% 5-year survival-rate for metastatic disease, with poorly understood links between genetic and environmental drivers of disease development, progression, and treatment response. Rhode Island has among the highest annual age-adjusted incidence rate of bladder cancer at 26.0/100,000, compared to 20.0 in the US, with a paucity of known driver genes for targeted therapies or predictive biomarkers. Bladder carcinomas have the highest frequency of alterations in CDKN1A/p21^WAF1 (10%) across all cancer types analyzed in The Cancer Genome Atlas (TCGA) PanCancer Atlas Studies, displaying a predominance of truncating mutations (86%). We found that lung carcinomas lack CDKN1A truncating mutations, despite the shared role of tobacco as a risk factor for bladder cancer. Bladder carcinomas also have the highest frequency of RB1 alterations in TCGA (25%). We find that chromophobe renal cell carcinomas with CDKN1A and RB1 mutations are 100% truncating. Analysis of 1,868 bladder tumors demonstrated that truncating CDKN1A mutations co-occur with truncating RB1 mutations, suggesting an environmental exposure signature. Moreover, we found that HRNR and FLG mutations are enriched in tumors with CDKN1A alteration, suggesting potential novel roles in promoting bladder tumorigenesis. Association of HRNR with AKT activation offers possible therapeutic avenues, and FLG may provide insight into carcinogen exposure within the bladder. We suggest that because APOBEC mutations largely shape the bladder cancer mutational landscape, these events likely contribute to dysfunctional DNA repair genes, leading to frameshifts and the predominance of truncations in CDKN1A, RB1, ARID1A, or other drivers. We propose that patients with co-occurrence of CDKN1A and RB1 truncations may display enhanced responsiveness to targeted therapies combining cisplatin with ATR, ATM, CHK1, and CHK2 inhibitors, expanding therapeutic options for patients in need of improved precision treatments.

Common Diagnostic Challenges and Pitfalls in Genitourinary Organs, With Emphasis on Immunohistochemical and Molecular Updates

CONTEXT.—

Lesions in the genitourinary (GU) organs, both benign and malignant, can demonstrate overlapping morphology, and practicing surgical pathologists should be aware of these potential pitfalls and consider a broad differential diagnosis for each specific type of lesion involving the GU organs. The following summary of the contents presented at the 6th Annual Chinese American Pathologists Association (CAPA) Diagnostic Course (October 10-11, 2020), supplemented with relevant literature review, exemplifies the common diagnostic challenges and pitfalls for mass lesions of the GU system of adults, including adrenal gland, with emphasis on immunohistochemical and molecular updates when relevant.

OBJECTIVE.—

To describe the common mass lesions in the GU system of adults, including adrenal gland, with emphasis on the diagnostic challenges and pitfalls that may arise in the pathologic assessment, and to highlight immunohistochemical workups and emerging molecular findings when relevant.

DATA SOURCES.—

The contents presented at the course and literature search comprise our data sources.

CONCLUSIONS.—

The diagnostic challenges and pitfalls that arise in the pathologic assessment of the mass lesions in the GU system of adults, including adrenal gland, are common. We summarize the contents presented at the course, supplemented with relevant literature review, and hope to provide a diagnostic framework to evaluate these lesions in routine clinical practice.

A case report of a patient with plasmacytoid urothelial cancer with significant response to HER2-targeting therapy and enfortumab vedotin

In this case report, we present a patient with the rare plasmacytoid variant of urothelial cancer. Notable elements of his course include: complete response to neoadjuvant paclitaxel, gemcitabine, cisplatin, development of metastatic disease to the rectum, sustained disease control with dual HER2 targeting therapy, and subsequent complete response to enfortumab vedotin. Plasmacytoid urothelial cancer accounts for just 1-3% of all urothelial cancer cases and is associated with more aggressive disease, with a propensity for intra-abdominal spread and poor response to neoadjuvant therapy. Preliminary data indicate that the variant may generally have high levels of HER2 expression. We review the history of HER2 targeting in metastatic urothelial cancer, which has included single-agent as well as combination with chemotherapy; there are ongoing biomarker-based clinical trials. Furthermore, we highlight the complete response to enfortumab vedotin. To date, this is the first report of efficacy for enfortumab vedotin in the plasmacytoid variant.

Multilayer spectrum of intratumoral heterogeneity in basal bladder cancer

Basal/squamous (Ba/Sq) subtype represents an intrinsic and robust group in the consensus molecular classification of muscle-invasive bladder cancer (MIBC), with poor outcome and controversial chemosensitivity. We aimed to investigate the spectrum of intratumor heterogeneity (ITH) in the Ba/Sq subtype. First, we validated a 29-gene NanoString CodeSet to predict the Ba/Sq subtype for FFPE samples. We identified heterogeneous Ba/Sq tumors in a series of 331 MIBC FFPE samples using dual GATA3/KRT5/6 immunohistochemistry (IHC). Heterogeneous regions with distinct immunostaining patterns were studied separately for gene expression using the 29-gene CodeSet, for mutations by targeted next-generation sequencing, and for copy number alteration (CNA) by microarray hybridization. Among 83 Ba/Sq tumors identified by GATA3/KRT5/6 dual staining, 19 tumors showed heterogeneity at the IHC level. In one third of the 19 cases, regions from the same tumor were classified in different distinct molecular subtypes. The mutational and CNA profiles confirmed the same clonal origin for IHC heterogeneous regions with possible subclonal evolution. Overall, two patterns of intratumoral heterogeneity (ITH) were observed in Ba/Sq tumors: low ITH (regions with distinct immunostaining, but common molecular subtype and shared CNA) or high ITH (regions with distinct immunostaining, molecular subtype, and CNA). These results showed multilayer heterogeneity in Ba/Sq MIBC. In view of personalized medicine, this heterogeneity adds complexity and should be taken into account for sampling procedures used for diagnosis and treatment choice. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Current Development and Application of Anaerobic Glycolytic Enzymes in Urothelial Cancer

Urothelial cancer is a malignant tumor with metastatic ability and high mortality. Malignant tumors of the urinary system include upper tract urothelial cancer and bladder cancer. In addition to typical genetic alterations and epigenetic modifications, metabolism-related events also occur in urothelial cancer. This metabolic reprogramming includes aberrant expression levels of genes, metabolites, and associated networks and pathways. In this review, we summarize the dysfunctions of glycolytic enzymes in urothelial cancer and discuss the relevant phenotype and signal transduction. Moreover, we describe potential prognostic factors and risks to the survival of clinical cancer patients. More importantly, based on several available databases, we explore relationships between glycolytic enzymes and genetic changes or drug responses in urothelial cancer cells. Current advances in glycolysis-based inhibitors and their combinations are also discussed. Combining all of the evidence, we indicate their potential value for further research in basic science and clinical applications.

Molecular Pathology of Urothelial Carcinoma

Urothelial carcinoma is characterized by the presence of a wide spectrum of histopathologic features and molecular alterations that contribute to its morphologic and genomic heterogeneity. It typically harbors high rates of somatic mutations with considerable genomic and transcriptional complexity and heterogeneity that is reflective of its varied histomorphologic and clinical features. This review provides an update on the recent advances in the molecular characterization and novel molecular taxonomy of urothelial carcinoma and variant histologies.

Outcomes of poorly differentiated and plasmacytoid variant bladder urothelial carcinoma

Objectives

The aim of this study is to assess the course and management of poorly differentiated bladder urothelial carcinoma (UC), including plasmacytoid UC (PUC), in our local area. Although bladder cancer is relatively common, PUC is a rare and aggressive subtype with a poor prognosis that is still poorly understood.

Materials and Methods

A retrospective assessment of all poorly differentiated high‐grade UC over the last 15 years (2005–2020) in the Hunter New England area was completed. In total, 37 patients were included, and PUC variant was compared with the remaining poorly differentiated UC.

Results

Of the included cases, eight were PUC, nine squamous variant, two neuroendocrine, and one sarcomatoid. Overall, 23 cases proceeded to cystectomy, 15 had chemotherapy (six neoadjuvant), and 11 had radiation therapy. In the PUC subgroup, three had metastatic disease at diagnosis (37.5%). Of the three PUC patients who underwent cystectomy, all were upstaged. Two PUC cases had adjuvant chemotherapy, and one case had radiation. Within the follow‐up period, the PUC group had a cause‐specific mortality of 50% with a mean survival in these patients of 202 days, compared with 37.9% cause‐specific mortality with survival of 671.55 days (p = 0.23) in all other undifferentiated UC cases; 5‐year cause‐specific mortality with Kaplan–Meier analysis was estimated at 26% compared with 59%, respectively (p = 0.058).

Conclusion

Poorly differentiated UC is demonstrated to have a poor prognosis with a high mortality rate, particularly when PUC is present. Given the rarity of these variants, further studies are necessary to explore the impact of current treatment options.

Plasmacytoid urothelial carcinoma (UC) are luminal tumors with similar CD8+ Tcell density and PD-L1 protein expression on immune cells as compared to conventional UC

BACKGROUND

Plasmacytoid urothelial carcinoma (UC) is a rare pathological variant of UC with low chemotherapeutic sensitivity and dismal outcomes. The molecular and immune profiles of such tumors remain poorly investigated.

METHODS

Herein, we investigated the phenotypical features of a cohort of plasmacytoid UC (n=32) by comparison to a control group of conventional high-grade UC with matched clinicopathological characteristics (n=30). Histopathological analysis included the following antibodies: p63, GATA3, CK5/6, CK20 and HER2. In addition, the density of intra-tumor CD8⁺ lymphocytes, and PD-L1 expression in tumor (TC) and immune cells (IC) were evaluated.

RESULTS

Plasmacytoid UC expressed GATA3 (97% vs 86% P=0.18), CK20 (59% vs 36% P=0.08) markers and showed a significantly higher rate of HER2 overexpression (2+ and 3+ score: 25% vs 0%, P<0.01) compared to controls. A significantly lower expression of CK5/6 (22% vs 56%, P<0.05) and p63 (41% vs 80%, P<0.05) was observed in plasmacytoid UC compared to controls. The density of tumor-infiltrating CD8+ cells was similar between plasmacytoid and conventional UC (P=0.9). PD-L1 expression on IC was similar compared to conventional UC (P=0.3).

CONCLUSIONS

Together, our study demonstrated that plasmacytoid UC belong to the luminal subtype and display a rather inflamed microenvironment similar to conventional UC. These data support the inclusion of plasmacytoid variant of UC in clinical trials evaluating immune checkpoint inhibitors monotherapy or combination immunotherapeutic strategies.

A 25-year perspective on advances in an understanding of the biology, evaluation, treatment and future directions/challenges of urothelial cancer

The Urologic Oncology Journal was founded 25 years ago and we reviewed the literature since that time in the area of urothelial cancer to see the progress and pitfalls we have made over this time period. A comprehensive literature search was conducted by the authors involved who are all actively involved in research, clinical trials, and treatment for urothelial cancer and the results were summarized over the past 25 years. The field of urothelial cancer has evolved tremendously in the last 25 years with the incorporation of molecular subtyping, novel imaging, immunotherapy, and robotic surgery. However, treatments such as BCG and radical cystectomy have remained steadfast over the last 25 years. Although we have a better understanding of the biology of bladder cancer, we still have a long way from being able to cure patients with bladder cancer and eliminate morbidity from treatments. Nevertheless, considerable progress has been made since the founding of the Urologic Oncology Journal 25 years ago.

Autocrine signaling by receptor tyrosine kinases in urothelial carcinoma of the bladder

Comprehensive characterizations of bladder cancer (BCa) have established molecular phenotype classes with distinct alterations and survival trends. Extending these studies within the tyrosine kinase (TK) family to identify disease drivers could improve our use of TK inhibitors to treat specific patient groups or individuals. We examined the expression distribution of TKs as a class (n = 89) in The Cancer Genome Atlas (TCGA) muscle invasive BCa data set (n >400). Patient profiles of potentially oncogenic alterations (overexpression and/or amplification) clustered TKs into 3 groups; alterations of group 1 and 3 TKs were associated with significantly worse patient survival relative to those without alterations. Many TK pathways induce epithelial-to-mesenchymal transition (EMT), which promotes tumor invasiveness and metastasis. Overexpression and/or amplification among 9 EMT transcriptional activators occurred in 43% of TCGA cases. Co-occurring alterations of TKs and EMT transcriptional activators involved most group 1 TKs; 24% of these events were associated with significantly worse patient survival. Co-occurring alterations of receptor TKs and their cognate ligands occurred in 16% of TCGA cases and several BCa-derived cell lines. Suppression of GAS6, MST1 or CSF1, or their respective receptors (AXL, MST1R and CSF1R), in BCa cell lines was associated with decreased receptor activation, cell migration, cell proliferation and anchorage independent cell growth. These studies reveal the patterns and prevalence of potentially oncogenic TK pathway-related alterations in BCa and identify specific alterations associated with reduced BCa patient survival. Detection of these features in BCa patients could better inform TK inhibitor use and improve clinical outcomes.

A 25 year perspective on advances in the pathologic assessment and diagnosis of urologic cancers

Over the past 25 years, diagnostic categories in genitourinary pathology have changed dramatically. Prostate cancer reporting incorporated numerous new variant categories, recognized the importance of intraductal carcinoma, and introduced the concept of Grade Groups. Pathologic diagnosis of bladder cancer not only added new variant categories, but also modified the grading of non-invasive urothelial neoplasms and refined staging definitions. Kidney cancer classification expanded from a handful of diagnostic categories to a broad array of additional cancer types defined by unique immunohistochemical and molecular findings. Segregation of penile carcinoma by human papillomavirus status more accurately reflected pathogenesis and helped improve prediction of cancer behavior. Testicular pathology research advanced understanding of germ cell tumor subtypes and their impact on patient outcomes. Finally, adrenal gland pathology has evolved to incorporate a broader recognition of morphological variation and risk factors associated with tumor progression. Taken together, changes in pathology over the past quarter century have revolutionized our approach to genitourinary cancers. This review seeks to highlight some of the many significant changes in genitourinary pathology that have occurred during the past 25 years and emphasize impacts on clinical outcomes or therapy, as relevant.

Clinicopathological and Genomic Profiles of Atypical Fibroxanthoma and Pleomorphic Dermal Sarcoma Identify Overlapping Signatures with a High Mutational Burden

Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) are rare tumors developing in chronically sun-exposed skin. Clinicopathological features are similar, but they differ in prognosis, while PDS has a more aggressive course with a higher risk for local recurrence and metastases. In current clinical practice, they are diagnosed by exclusion using immunohistochemistry. Thus, stringent diagnostic criteria and correct differentiation are critical in management and treatment for optimal outcomes. This retrospective single-center study collected clinicopathological data and tumor samples of 10 AFX and 18 PDS. Extracted genomic DNA from tumor specimens was analyzed by a next-generation sequencing (NGS) platform (FoundationOne-CDx™). Among 65 identified mutations, TP53 inactivating mutations were observed in all tumor specimens. In both AFX and PDS, the known pathogenic gene alterations in CDKN2A, TERT promoter, and NOTCH1 were frequently present, along with high mutational burden and stable Micro-Satellite Instability status. The mutational profiles differed only in ASXL1, which was only present in AFX. Further differences were identified in likely pathogenic and unknown gene alterations. Similarities in their genomic signatures could help to distinguish them from other malignancies, but they are not distinguishable between each other using the FoundationOne-CDx™ NGS panel. Therefore, histological criteria to determine diagnosis remain valid. For further insight, performing deep tumor profiling may be necessary.

Non-Muscle Invasive Bladder Cancer with Variant Histology: Biological Features and Clinical Implications

BACKGROUND

The most common bladder cancer (BC) histotype is pure urothelial carcinoma (UC), which may undergo divergent differentiation in some cases. Variant histology (VH) presents along variable morphologies, either single or combined between them or with pure UC. From a clinical standpoint, the vast majority of BC is diagnosed at non-invasive or minimally invasive stages, namely as non-muscle invasive BC (NMIBC). There is a wide range of therapeutic options for patients with NMIBC, according to their clinical and pathological features. However, current risk stratification models do not show optimal effectiveness. Evidence from the literature suggests that VH has peculiar biological features, and may be associated with poorer survival outcomes compared to pure UC.

SUMMARY

In order to describe the biological features and prognostic/predictive role of VH in NMIBC, and to discuss current treatment options, we performed a systematic literature search through multiple databases (PubMed/Medline, Google Scholar) for relevant articles according to the following terms, single and/or in combination: "non-muscle invasive bladder cancer," "variant histology," "micropapillary variant," "glandular differentiation," "squamous differentiation," "nested variant," "plasmacytoid variant," and "sarcomatoid variant." We extracted 99 studies including original articles, reviews, and systematic reviews, and subsequently analyzed data from 16 studies reporting on the outcome of NMIBC with VH. We found that the relative rarity of these forms as well as the heterogeneity in study populations and therapeutic protocols results in conflicting findings overall. Key Messages: The presence of VH should be taken into account when counseling a patient with NMIBC, since it may upgrade the disease to high-risk tumor and thus warrant a more aggressive treatment.

Primary Signet Ring Cell/Histiocytoid Carcinoma of the Eyelid: Somatic Mutations in CDH1 and Other Clinically Actionable Mutations Imply Early Use of Targeted Agents

Primary signet ring cell/histiocytoid carcinoma of the eyelid is a rare ocular malignancy and its diagnosis is often delayed. This neoplasm presents as an insidious, diffusely infiltrative mass in the periocular area that later infiltrates the orbit. An exenteration is usually indicated; however, nearly one-third of patients develop local recurrence or metastasis. Morphologically, it resembles signet ring cell carcinoma of the stomach and breast, raising the possibility of mutations in CDH1, the gene encoding E-cadherin. To determine whether primary signet ring cell/histiocytoid carcinoma harbors the CDH1 mutation or other actionable mutations, we analyzed the tumor tissue via next-generation sequencing. We identified only one case of primary signet ring cell carcinoma of the eyelid with adequate DNA quality for sequencing from the pathological archive during the period 2000 to 2020. A comprehensive evaluation including histopathology, immunohistochemistry, and next-generation sequencing assay was performed on tumor tissue. Immunohistochemically, the tumor exhibited E-cadherin membranous staining with the aberrant cytoplasmic staining of β-catenin. Using next-generation sequencing, we demonstrated the mutation in the CDH1 gene. In addition, other clinically actionable mutations including ERBB2 and PIK3CA were also detected. The alterations in other actionable genes indicate a need for larger studies to evaluate the pathogenesis and potential therapies for primary signet ring cell/histiocytoid carcinoma of the eyelid.

Natural history, response to systemic therapy, and genomic landscape of plasmacytoid urothelial carcinoma

Background

Plasmacytoid urothelial carcinoma (PUC) is a rare, aggressive histologic variant of urothelial cancer characterised by a diffuse growth pattern and CDH1 mutation. We studied the efficacy of preoperative platinum-based chemotherapy in nonmetastatic PUC and immune checkpoint inhibitors (ICIs) in advanced PUC.

Methods

Cases of nonmetastatic PUC and advanced PUC treated with ICIs at our institution were identified. Outcomes were compared to those of a published cohort of patients with urothelial carcinoma not otherwise specified.

Results

We identified 81 patients with nonmetastatic PUC. Of the patients with localised disease who underwent neoadjuvant chemotherapy, pathologic complete response and downstaging rates were 12 and 21%, respectively. Pathologic downstaging was not associated with significant improvement in clinical outcomes. Up to 18% of localised disease and 28% of locally advanced cases had unresectable disease at the time of surgery. ICI-treated advanced PUC (N = 21) had progression-free and overall survival of 4.5 and 10.5 months, respectively, and a 38% response rate. FGFR3 and DNA damage response gene alterations were observed in 3 and 15% of cases, respectively.

Conclusions

PUC is associated with high disease burden and poor chemosensitivity. Increased awareness and recognition of this disease variant will allow for new treatment strategies.

Clinicopathologic Study of Gleason Pattern 5 Prostatic Adenocarcinoma With "Single-cell" Growth Reveals 2 Distinct Types, One With "Plasmacytoid" Features

Each Gleason score category of prostatic adenocarcinoma (or Grade Group) may encompass a diverse group of architectural patterns such as well-formed glands, poorly formed glands, cribriform structures, single cells, and/or solid sheets. We have noted heterogeneity within the single-cell subtype of Gleason pattern 5 prostatic adenocarcinoma that has not been fully addressed. Therefore, we retrospectively reviewed a series of radical prostatectomies with high-grade prostatic adenocarcinoma (Grade Group 4 or 5), identifying tumors with a component of single-cell infiltration. Additional cases identified prospectively were also included. TNM status, association with other histologic patterns, and clinical follow-up status were determined. Immunohistochemistry for NKX3.1, E-cadherin, p120 catenin, and prostate-specific antigen (PSA) were performed in each case. Eighteen cases with a component of well-developed Gleason pattern 5 characterized by single infiltrative cells that comprised ≥5% of the tumor were identified (15/202 retrospective radical prostatectomies with the high-grade disease [7.5%]). The single-cell pattern ranged from 5% to 50% of the tumor volume, with 5 cases containing ≥40%, and variable secondary architecture included diffuse infiltrating single cells with targetoid growth pattern around benign glands, solid expansive nests of noncohesive cells, and corded/single file growth pattern. Further morphologic analysis demonstrated 2 distinct histologic subtypes: (1) (subtype 1; n=9) monomorphic "plasmacytoid" tumor cells with eccentrically placed nuclei and variable intracytoplasmic vacuoles with bland cytology and discohesion and (2) (subtype 2; n=9) more cohesive tumor cells with greater cytologic atypia characterized by prominent nucleoli, greater variability in nuclear size/shape, occasional mitotic figures, and more irregular infiltration. By immunohistochemistry, NKX3.1 nuclear expression and PSA cytoplasmic expression was retained in all cases. Concomitant membranous E-cadherin loss and strong cytoplasmic p120 catenin expression were present in 5 of the 18 (28%) cases, all in subtype 1 (5/9, 56%). Overall, 56% (10/18) of patients had advanced-stage disease (≥pT3b), and 70% (7/10) of these patients had associated lymphovascular invasion. All patients had concomitant cribriform patterns of carcinoma. The outcome was available for 14 patients: 4 died of unknown cause; 6 had biochemical recurrence with distant bone metastasis in 5 of the 6; and 4 patients with <3 years of follow-up currently have undetectable serum PSA levels (2 patients received salvage radiotherapy with androgen deprivation and 2 remain on routine follow-up). In summary, the single-cell pattern of Gleason pattern 5 prostatic adenocarcinoma is uniformly associated with other high-risk histologic patterns (eg, cribriform growth), and high-stage disease with distant metastasis is not uncommon. Our data suggest that the "single-cell" Gleason pattern 5 prostatic adenocarcinoma contains 2 distinct subtypes. Somatic CDH1 alterations may play a role in the development of the "plasmacytoid" pattern characterized by monomorphic cytology with concomitant E-cadherin loss and aberrant p120 catenin expression.