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Bladder

Benign urothelial lesions

Dysplasia


Reviewer: Monika Roychowdhury, M.D., University of Minnesota Medical Center (see Reviewers page)
Revised: 21 April 2011, last major update April 2011
Copyright: (c) 2003-2011, PathologyOutlines.com, Inc.

Definition
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● Lesions of flat, noninvasive urothelium with appreciable cytologic and architectural changes indicative of neoplasia, but less than carcinoma in situ
● Represents an early morphologic manifestation of progressive alterations between normal urothelium and carcinoma in situ

Terminology
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● Also known as low grade intraurothelial neoplasia (LG IUN)

Epidemiology
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● Mean age 60 years, 75% male

Sites
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● More common on posterior wall

Clinical features
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● Occurs de novo (primary) or in patients with concurrent or previous urothelial neoplasms (secondary)
● 2/3 have irritative symptoms or hematuria; 1/3 have no symptoms
● 14-19% develop biopsy-proven progression (Cancer 2000;88:625, Am J Surg Pathol 1999;23: 443-7)

Prognostic factors
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● Secondary dysplasia is more common than primary and has a higher rate of progression to carcinoma than de novo dysplasia (30-36% versus 14-19%)
● Only 3-10% die of bladder cancer over a 10-25 year period

Micro description
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● Characterized by lack of maturation in basal and intermediate cell layers (not full thickness)
● Normal urothelial thickness (may be increased or decreased) and superficial umbrella cells are present
● Atypical cytological changes restricted to intermediate and basal cells
● Variable mitotic activity
● Normal lamina propria
● Low interobserver agreement on diagnosis, even among experts

Micro images
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Series of images


Urothelial dysplasia

Cytology
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● Usually normal
● Loss of cytoplasmic clearing and nuclear polarity
● Nuclear enlargement, nuclear membrane irregularities and nuclear hyperchromasia

Positive stains
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● CK20 (aberrant expression in deeper layers), p53

Negative stains
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● CD44

Differential diagnosis
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Flat lesions with reactive atypia: inflammatory atypia characterized by mild nuclear abnormalities in acutely or chronically inflamed urothelium
Flat lesions with atypia of unknown significance: atypia insufficient for diagnosis of dysplasia
Carcinoma in situ: flat lesion composed of cells in mid to upper epithelium with high cytologic grade

Additional references
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Hum Pathol 2010;41:155

End of Bladder > Benign urothelial lesions > Dysplasia


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