title: Schneiderian papillomas: comparative review of exophytic, oncocytic, and inverted types.
abstract: BACKGROUND
  Sinonasal papillomas are benign epithelial neoplasms arising from Schneiderian mucosa. The three subtypes, exophytic, oncocytic, and inverted (inverted papilloma [IP]), should be distinguished from one another histopathologically. This study (1) highlights the histopathological and clinical differences between the Schneiderian papilloma subtypes and (2) identifies clinical features that potentially predict papilloma subtypes.
  
  
  METHODS
  A retrospective review was performed of patients with Schneiderian papillomas over an 11-year period.
  
  
  RESULTS
  Seventy patients with sinonasal papillomas who underwent sinus surgery were identified. There were 50 (71%) male and 20 (29%) female subjects diagnosed at an average age of 53 years (range, 13-80 years). Exophytic (n = 25), oncocytic (n = 9), and IP (n = 37) were identified. IP was associated with transformation into squamous cell carcinoma in three (8%) cases and dysplasia in three (8%) cases. Neither oncocytic nor exophytic subtypes were associated with dysplasia or malignancy. On multivariate analysis of potential predictors of papilloma subtype, history of chronic rhinosinusitis (CRS) and location of papilloma were significantly associated with papilloma subtype. Using classification and regression tree model, papilloma subtypes can be predicted based on presence or absence of CRS and papilloma location with nominal 82.4% accuracy.
  
  
  CONCLUSIONS
  The inverted and exophytic type are the most common sinonasal papillomas, with the inverted type having an 8% rate of malignant transformation in this study. In contrast, the oncocytic type was not associated with dysplasia or malignancy in our series despite reports in the literature indicating malignant potential. History of CRS and papilloma location can provide clues to the histological subtype, which is important for surgical planning and patient counseling.
authors.affiliation: Head and Neck Surgery, University of California-Los Angeles, 10833 Le Conte Avenue, Los Angeles, CA 90095-1624, USA. nvorasubin@mednet.ucla.edu
authors.forename: Nopawan
authors.initials: N
authors.lastname: Vorasubin
authors.forename: Darshni
authors.initials: D
authors.lastname: Vira
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Suh
authors.forename: Sunita
authors.initials: S
authors.lastname: Bhuta
authors.forename: Marilene B
authors.initials: MB
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002471:Cell Transformation, Neoplastic / Q000473:pathology; D004847:Epithelial Cells / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008444:Maxillary Sinus Neoplasms / Q000145:classification / Q000473:pathology* / Q000601:surgery*; D008875:Middle Aged; D009297:Nasal Mucosa / Q000473:pathology; D009669:Nose Neoplasms / Q000473:pathology / Q000601:surgery; D010212:Papilloma / Q000145:classification / Q000473:pathology* / Q000601:surgery*; D018308:Papilloma, Inverted / Q000473:pathology / Q000601:surgery; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome