Clinical and Genomic Characterization of Bladder Carcinomas With Glandular Phenotype

[Rare tumors and tumor types of the urinary system in the 5th edition of the WHO classification 2022]

The 5th edition of the World Health Organization (WHO) classification of tumors of the urinary tract and male genital organs introduced both general and specific changes in structure, classification, and nomenclature. This also applies to rarer tumors and tumor subtypes of the urinary system. Knowledge of these changes is relevant for routine histopathological work. This article provides an overview of the main new features of the rarer tumors and tumor subtypes of the urinary system in the new edition of the WHO classification.

Glandular Lesions of the Urinary Bladder: Diagnostic and Molecular Updates

Glandular lesions in the urinary tract or their associated pathologies can pose a diagnostic challenge. There is a variety of benign alterations and tumor types that need to be taken into account in differential diagnostic considerations. In recent times, efforts for better defining these alterations or lesions both on the histopathological and molecular levels have been undertaken. This article will provide an update on current diagnostic and molecular considerations of these lesions.

Mutational signature and prognosis in adenocarcinoma of the bladder

Adenocarcinoma of the bladder is a rare urinary bladder carcinoma with limited therapy options due to lack of molecular characterization. Here, we aimed to reveal the mutational and transcriptomic landscapes of adenocarcinoma of the bladder and assess any relationship with prognosis. Between February 2015 and June 2021, a total of 23 patients with adenocarcinoma of the bladder were enrolled. These included 16 patients with primary bladder adenocarcinomas and seven patients with urachal adenocarcinoma. Whole exome sequencing (16 patients), whole genome sequencing (16 patients), bulk RNA sequencing (RNA-seq) (19 patients), and single-cell RNA-seq (5 patients) were conducted for the specimens. Correlation analysis, survival analysis, and t-tests were also performed. Prevalent T>A substitutions were observed among somatic mutations, and major trinucleotide contexts included 5'-CTC-3' and 5'-CTG-3'. This pattern was mainly contributed by COSMIC signature 22 related to chemical carcinogen exposure (probably aristolochic acid), which has not been reported in bladder adenocarcinoma. Moreover, genes with copy number changes were also enriched in the KEGG term 'chemical carcinogenesis'. Transcriptomic analysis suggested high immune cell infiltration and luminal-like features in the majority of samples. Interestingly, a small fraction of samples with an APOBEC-derived mutational signature exhibited a higher risk of disease progression compared with samples with only a chemical carcinogen-related signature, confirming the molecular and prognostic heterogeneity of bladder adenocarcinoma. This study presents mutational and transcriptomic landscapes of bladder adenocarcinoma, and indicates that a chemical carcinogen-related mutational signature may be related to a better prognosis compared with an APOBEC signature in adenocarcinoma of the bladder. © 2024 The Pathological Society of Great Britain and Ireland.

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.

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.