Urothelial carcinoma with squamous differentiation—The pathologists׳ perspective

• Urothelial carcinoma commonly exhibits divergent histology, most commonly in the form of squamous differentiation.
• The definition, prevalence and extent of squamous differentiation in bladder cancer is discussed.
• New immunohistochemical and molecular markers may help to identify tumors with squamous differentiation and may provide correlation with molecular subtypes in bladder cancer.

Squamous differentiation is the most common variant histology in urothelial carcinoma and may have effects on clinical outcome. Inconsistencies in reporting variant histologies in urothelial carcinoma are well documented. Immunohistochemical and molecular markers may help identify tumors with squamous differentiation beyond light microscopy.