Non‐urothelial carcinomas of the bladder

Abstract

Non‐urothelial carcinomas involving the bladder are uncommon and often diagnostically challenging. These carcinomas may show squamous, adenocarcinomatous or neuroendocrine features, with immunohistochemical stains aiding the diagnosis in only a subset of cases. The clinical history in non‐urothelial bladder carcinomas is important, given that the differential diagnosis often includes secondary involvement of the bladder by direct extension or metastasis from carcinomas at other sites. This paper will review non‐urothelial carcinomas in each of these three morphological categories, emphasising recent changes in diagnostic grouping and challenges in the histopathological diagnosis. Review of bladder cancers with squamous morphology will include discussion of conventional squamous cell carcinoma and verrucous carcinoma and their distinction from urothelial carcinoma with extensive squamous differentiation. Bladder carcinomas with adenocarcinomatous change will include primary bladder adenocarcinoma, urachal adenocarcinoma and tumours of Müllerian type. Finally, neuroendocrine neoplasms of the bladder, including well‐differentiated neuroendocrine tumour and neuroendocrine carcinomas, will be discussed. Associated surface findings, risk factors and prognostic features will be described.

Clinical Characteristics, Treatment Strategy, and Outcomes of Primary Large Cell Neuroendocrine Carcinoma of the Bladder: A Case Report and Systematic Review of the Literature

“…Urinary bladder cancer (BCa) is the 10th most common malignancy cancer worldwide, with an estimated 549,393 new cases and 199,922 deaths in 2018 ( 1 ). However, non-urothelial cancers of the urinary bladder are relatively rare, accounting for only 5% of all BCa ( 2 , 3 ). Moreover, primary bladder neuroendocrine carcinoma is an extremely rare but heterogeneous variation of non-urothelial carcinoma of the urinary bladder, representing <1% of urinary bladder neoplasms.…”

The Value of Preoperative Alpha-L-Fucosidase Levels in Evaluation of Malignancy and Differential Diagnosis of Urothelial Neoplasms

“…Previous studies have shown that squamous differentiation is more resistant to radiotherapy, chemotherapy, and immunotherapy and possesses the characteristics of high risk of recurrence and poor prognosis as an independent prognostic factor of UC [2,14,15]. In addition, SqCC, as the most common variant in nonurothelial carcinomas, is usually discovered and diagnosed at its advanced stage, while a considerable number of patients have lymph node metastasis in neoplasms resection [5,16]. Currently, there are limited clinical approaches for the early diagnosis and treatment of MUT.…”

“…However, previous research has shown that nUC confer a worse prognosis and are more resistant to conventional treatment [ 4 ]. The differential diagnosis of pure UC (UC without divergent differentiations), UCSD, and SqCC relies not only on histopathological features, but also on sufficient precedent pathology and medical history taking [ 5 ]. Therefore, there is an urgent need to find a sensitive biological marker to identify SqCC, UC, and UCSD and evaluate the malignant degree of them.…”

Unusual Faces of Bladder Cancer

“…Genuine verrucous carcinoma is a rare tumor subtype in the urinary tract [31], however, conventional well-differentiated squamous cell carcinoma with "verrucous" architectural features is a much more common event. Since the difference between them has prognostic implications their correct identification by the pathologist matters.…”