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Urothelial carcinoma-invasive

With squamous differentiation

Reviewer: Nat Pernick, M.D., PathologyOutlines.com, Inc. (see Reviewers page)
Revised: 30 June 2011, last major update June 2011
Copyright: (c) 2003-2011, PathologyOutlines.com, Inc.


● Mixed variant with malignant urothelial and squamous components (either component may be in situ only)


● Occurs in 21% of urothelial carcinomas of bladder (Arch Pathol Lab Med 2007;131:1244)

Clinical features

● Clinical significance uncertain, but appears to be unfavorable prognostic factor (Int Braz J Urol 2007;33:339, Urology 2007;70:69)
● May be resistant to radiotherapy (J Clin Pathol 1989;42:250)

Micro description

● Associated with high grade urothelial carcinoma
● By definition, must also have an identifiable malignant urothelial component (may be only carcinoma in situ)
● Squamous component has nests of malignant squamous epithelium, characterized by polygonal cells and evidence of keratinization (dyskeratosis, keratin pearls) or intercellular bridges
● Squamous component may have basaloid or clear cell features
● Associated with eosinophils (J Clin Pathol 1984;37:500)
● Recommended to report percentage of squamous component

Micro images


High grade tumor

Keratin pearls

Figure 1

Poorly differentiated tumor with squamous differentiation


Various images

Positive stains

Squamous component: CK14, Mac387 (L1 antigen, J Clin Pathol 2007;60:332)
● Also CK5/6, CK5/14 (Virchows Arch 2011;458:301), caveolin-1 (Am J Clin Pathol 2003;120:93)

Negative stains

Squamous component: uroplakins (positive in urothelial component), CK20

Differential diagnosis

Squamous cell carcinoma: no associated urothelial component (i.e. pure squamous cell component)

End of Bladder > Urothelial carcinoma-invasive > With squamous differentiation

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