[Transitional tumours of urinary bladder (author's transl)]

Area of Science:

• Urothelial biology and oncology.
• Investigates the complex structure and regenerative capabilities of bladder transitional epithelium.

Context:

• Leverages recent literature and scanning electron microscopy findings.
• Addresses the classification and diagnostic challenges of urothelial carcinomas.

Purpose:

• To provide a comprehensive overview of bladder transitional epithelium and its associated carcinomas.
• To detail the classification of both invasive and non-invasive urothelial tumors.
• To highlight the significance of abnormal regeneration and the diagnostic difficulties in biopsies.

Summary:

• Transitional epithelium, despite its reputation, is complex with specialized cells and significant regenerative powers.
• Bladder carcinomas are classified by basal lamina integrity, invasion depth, metaplasia, and Broders' grade, with correlations noted.
• Non-invasive tumors include papillary and flat types, while abnormal regeneration, dysplasia, and hyperplasia indicate high risk and require surveillance.
• Histopathological analysis of urothelial tumors is straightforward in surgical specimens but challenging in biopsies, necessitating surgeon-pathologist collaboration.

Impact:

• Enhances understanding of urothelial carcinoma classification and risk stratification.
• Underscores the importance of accurate histopathological evaluation and interdisciplinary cooperation.
• Informs clinical surveillance strategies for patients with bladder lesions.