Urothelial carcinoma in situ: diagnostic update

Zosteriform cutaneous metastases from urothelial carcinoma: Report of a rare case and literature review

Zosteriform cutaneous metastases from urothelial carcinoma are rare. Here, we report a 50-year-old male with urothelial carcinoma who presented with multiple tender, erythematous papulonodules in an L1-L3 distribution approximately 6 years after primary tumor diagnosis. He had no history of prior herpes zoster infection. Histopathology showed lobules and small nests of atypical epithelioid cells positive for GATA3, CK20, CK7, and p40 throughout the dermis and within lymphatic vessels highlighted by D2-40, consistent with cutaneous metastases from urothelial carcinoma. No perineural invasion or viral cytopathic change was present. The patient died approximately 8 months after diagnosis of cutaneous metastases. Since its first report in 1986, there have been only six cases of zosteriform cutaneous metastases from urothelial carcinoma. We review the prior literature including hypotheses of the pathogenesis of zosteriform cutaneous metastases, which remain incompletely understood.

Urothelial carcinoma in situ with "overriding" features can evade detection by mimicking umbrella cells

Urothelial carcinoma in situ (uCIS) is typically recognized by overtly malignant cells with characteristic nuclear features; multiple histologic patterns have been described. A rare "overriding" pattern, in which uCIS tumor cells extend on top of normal urothelium, has previously been mentioned in the literature, but not well-described. Herein, we report three cases of uCIS with "overriding" features. Detailed morphologic evaluation revealed somewhat subtle cytologic atypia: variably enlarged hyperchromatic nuclei, scattered mitotic figures but with abundant cytoplasm and limited to superficial urothelium. Immunohistochemical (IHC) analysis showed a distinctive diffuse positive aberrant p53 pattern, limited to the atypical surface urothelial cells; these cells were also CK20+, CD44-, and Ki67 increased. In two cases, there was a history of urothelial carcinoma and adjacent conventional uCIS. In the third case, the "overriding" pattern was the first presentation of urothelial carcinoma; therefore next generation sequencing molecular testing was also performed, revealing pathogenic mutations in TERTp, TP53, and CDKN1a to further support neoplasia. Notably, the "overriding" pattern mimicked umbrella cells, which normally line surface urothelium, can have abundant cytoplasm, more variation in nuclear and cell size and shape, and show CK20+ IHC. We therefore also evaluated umbrella cell IHC patterns in adjacent benign/reactive urothelium, which showed CK20+, CD44-, p53 wild-type and very low Ki67 (3/3). We also reviewed 32 cases of normal/reactive urothelium: all showed p53 wild-type IHC in the umbrella cell layer (32/32). In conclusion, caution is warranted to avoid overdiagnosis of usual umbrella cells as CIS; however, "overriding" uCIS should be recognized, may have morphologic features that fall short of the diagnostic threshold of conventional CIS, and requires further study.

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.

Scoring Systems for Immunohistochemistry in Urothelial Carcinoma

Immunohistochemistry is widely used in diagnostic and scientific analysis of urothelial carcinoma. Objective interpretation of staining results is mandatory for accuracy and comparability in diagnostic and therapeutic patient care as well as research.Herein we summarize and explain standardized microscopic evaluation and scoring approaches for immunohistochemical stainings. We focus on commonly used and generally feasible approaches for different cellular compartments and comment on their utility in diagnostics and research practice.

Flat intraurothelial lesions of the urinary bladder-do hyperplasia, dysplasia, and atypia of unknown significance need to exist as diagnostic entities? and how to handle in routine clinical practice

Classification of the putative flat preneoplastic and neoplastic lesions of the urothelium with features subthreshold for urothelial carcinoma in situ remains a challenging, indeed, vexing problem in diagnostic surgical pathology. This area, subtending lesions including flat urothelial hyperplasia, urothelial dysplasia, and atypia of unknown significance, has struggled under evolving classifications, changing criteria, and limited clinical actionability, all confounded by the recognized lack of diagnostic reproducibility. Herein, we review the state of the literature around these lesions, reviewing contemporary criteria and definitions, assessing the arguments in favor and against of retaining hyperplasia, dysplasia, and atypia of unknown significance as diagnostic entities. We clarify the intent of the original definitions for dysplasia as a lesion felt to be clearly neoplastic but with morphologic features that fall short of the threshold of urothelial carcinoma in situ. While several pathologists, including some experts in the field, conflate the term dysplasia with urothelial atypia of unknown significance, the latter is defined as a descriptive diagnosis term to express diagnostic uncertainty of a lesion of whether it is clearly reactive or neoplastic. Both molecular studies and clinical needs are considered, as we outline our approach on diagnosing each of these lesions in clinical practice. Recommendations are made to guide consistency and interoperability in future scholarship, and the place of these lesions in context of evolving trends in the field is considered.