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Bladder

Benign tumors

Villous adenoma

Reviewer: Monika Roychowdhury, M.D., University of Minnesota Medical Center (see Reviewers page)
Revised: 6 May 2011, last major update April 2011
Copyright: (c) 2003-2011, PathologyOutlines.com, Inc.

Definition
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● Rare bladder tumor similar to colonic counterpart

Terminology
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● Also called villous tumor

Epidemiology
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● Rare
● Typically elderly patients, more commonly found in men (Int J Urol 2008;15:551)
● Wide age range, but usually 40-70 years

Sites
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● Arise throughout urinary tract, but most common in bladder
● In bladder, dome and the posterior wall are the most common sites; also urachus and trigone

Clinical features
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● Hematuria, mucusuria and irritative symptoms
● May be associated with in situ or invasive adenocarcinoma at diagnosis, less often with in situ or invasive urothelial carcinoma

Prognostic factors
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● Excellent prognosis if isolated, poorer if only in-situ adenocarcinoma and well sampled, poorest if in situ or invasive urothelial carcinoma (Hum Pathol 2002;33:236)

Case reports
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● Arising in background of chronic cystitis, aneuploid (Mod Pathol 1999;12:735)
● 41 year old patient with hematuria (J Med Assoc Thai 2010;93:1336)
● 48 year old woman with gross hematuria (Int J Urol 2008;15:551)
● 62 year old woman with tumor in augmented bladder 44 years after surgery (Int J Urol 2006;13:1134)
● 66 year old man with tumor in urinary diversion pouch (Int J Urol 2007;14:865)
● 75 year old man with coexisting mucinous adenocarcinoma (J Clin Pathol 2003;56:465)

Treatment
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● Excision
● Excellent prognosis if isolated (Am J Surg Pathol 1999;23:764)

Gross description
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● Resembles papillary urothelial carcinoma

Micro description
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● Resembles colonic villous adenoma with pointed processes lined by pseudostratified columnar epithelium with nuclear stratification, nuclear crowding, nuclear hyperchromasia, occasional prominent nucleoli, occasional mitoses
● Associated with cystitis glandularis and cystitis cystica
● MUST sample entire lesion to rule out adenocarcinoma (in situ or invasive)

Micro images
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Arising in urachal cyst


Finger-like projections


Resembles colonic adenoma


Papillary fronds covered by columnar epithelium with goblet cells, and nuclear crowding and stratification

   
AFIP Fig 2-52: Polypoid and villous adenoma arising at bladder dome

   
With coexisting adenocarcinoma

Positive stains
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● Acidic mucins (Alcian blue), CK20, CEA (luminal, 89%)
● CK7 (56%), EMA (22%); variable prostate specific membrane antigen (Am J Surg Pathol 2008;32:1322)

Negative stains
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● EMA

Differential diagnosis
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● Well-differentiated colonic adenocarcinoma extending into bladder: clinical history, definite invasion
● Florid cystitis glandularis: lacks well formed villous structure

End of Bladder > Benign tumors > Villous adenoma

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