inverted urothelial papilloma


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  • Clinical

    • age: peaks 60-70s
    • male > female (4:1)
    • location: bladder (70%, trigone most common), ureter, renal pelvis, urethra

  • Histology

    • inverted papillary architecture: urothelial cells facing central fibrovascular core, basal cells face outward
    • benign cytology: lack mitosis, lack nucleoli, fine chromatin, uniform nucleus
    • focal squamous metaplasia, nonkeratinizing
    • subtypes
      • trabecular: interanastomosing sheets, cystic areas
      • glandular
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