What About Variant Histologies in Bladder Cancer?

Approximately 25% of bladder cancers exhibit variant histology, an updated term used in the 2022 World Health Organization histological classification of bladder cancer. These variant histologies differ by molecular pattern and clinical behaviour, and there are some differences in treatment recommendations in comparison to pure urothelial carcinoma (UC). Some UCs also exhibit nonconventional histologic features in addition to a urothelial component. Treatment is similar for UCs with nonconventional and conventional histologies. Data on neoadjuvant treatment, bladder preservation, adjuvant treatment, and the impact of new therapies are limited for plasmacytoid, micropapillary, sarcomatoid, neuroendocrine, squamous, and adenocarcinoma variants. Therefore, upfront radical cystectomy is traditionally recommended for local management. It is important to recognise UC subtypes and their differential management. Clinical trials focusing specifically on these variant subtypes of bladder cancer are needed. Patient summary In this paper we summarize key points for the management of uncommon bladder cancer types. We highlight the importance of correct diagnosis of these tumours for selection of the most suitable treatment.