title: Inverted Papilloma of the Bladder Coexisting with Urothelial Carcinoma. A Case Report.
abstract: BACKGROUND
  Inverted papilloma (IP) is an unusual benign neoplasm, most commonly found in the bladder. Cases of malignant transformation have been reported in the past, although most of them are now considered to be urothelial carcinomas with an inverted growth pattern.
  
  
  METHODS
  A 54-year-old man was diagnosed with urothelial carcinoma in situ (UCIS), high-grade papillary urothelial carcinoma (HGPUC), and IP by transurethral resection specimen of the bladder. The urothelial carcinoma cells were seen colonizing the inverted papilloma.
  
  
  CONCLUSIONS
  The coexistence of IP with UCIS and HGPUC is rare. Immunohistochemistry helps distinguish between IP and UC in difficult cases such as this one. A brief review of other reported cases of inverted papilloma coexisting with urothelial carcinoma in the English literature over the past 25 years is presented.
authors.forename: Ricardo Santana
authors.initials: RS
authors.lastname: Veiga
authors.forename: João
authors.initials: J
authors.lastname: Cassis
authors.forename: Pedro
authors.initials: P
authors.lastname: Oliveira
authors.forename: António
authors.initials: A
authors.lastname: Lopez-Beltran
mesh_terms: D014408:Biomarkers, Tumor; D002295:Carcinoma, Transitional Cell / Q000150:complications / Q000175:diagnosis / Q000473:pathology*; D002471:Cell Transformation, Neoplastic / Q000473:pathology; D003937:Diagnosis, Differential; D006801:Humans; D008297:Male; D008875:Middle Aged; D018308:Papilloma, Inverted / Q000150:complications / Q000175:diagnosis / Q000473:pathology*; D011379:Prognosis; D001743:Urinary Bladder / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor