• A type of tumor in which surface epithelial cells grow downward into the underlying supportive tissue. It may occur in the nose and/or sinuses or in the urinary tract (bladder, renal pelvis, ureter, urethra). When it occurs in the nose or sinuses, it may cause symptoms similar to those caused by sinusitis, such as nasal congestion. When it occurs in the urinary tract, it may cause blood in the urine.
  NCI Dictionary of Cancer Terms
  U.S. National Cancer Institute, 2021
• An endophytic benign papillary epithelial neoplasm that results from the invagination and proliferation of epithelial cells in the underlying stroma. Representative examples are the inverted urothelial papilloma that arises from the urinary tract and inverted Schneiderian papilloma that arises from the nasal cavity or paranasal sinuses.
  NCI
  U.S. National Cancer Institute, 2021
• (papilloma, inverted) A mucosal tumor of the urinary bladder or nasal cavity in which proliferating epithelium is invaginated beneath the surface and is more smoothly rounded than in other papillomas. (Stedman, 25th ed)
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2025