Lung tumor
Benign tumors
Squamous papilloma

Author: Roseann Wu, M.D. (see Authors page)

Revised: 1 February 2016, last major update January 2016

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed Search: Squamous papilloma [title]
Definition / General
Epidemiology
  • Solitary endobronchial papillomas in adults is rare, < 0.5% of lung tumors
  • Squamous papillomas usually occur in middle aged male smokers
Terminology
  • Also called squamous cell papilloma, solitary tracheobronchial papilloma
  • Termed papillomatosis if multiple lesions present
Clinical Features
  • Associated with HPV 6 and HPV 11; high risk HPV may be seen in cases associated with carcinoma (Hum Pathol 1994;25:1191)
  • Noninvasive but may have dysplasia, recur or develop into squamous cell carcinoma
  • Nonspecific lower respiratory tract complaints include hemoptysis, recurrent pneumonia, asthma-like symptoms, dry cough
  • Rarely arises in lower bronchial tree, but usually manifests as endobronchial exophytic growth
Diagnosis
  • May be difficult on frozen section and small biopsy specimens to distinguish from squamous carcinoma
Radiology Description
  • May be incidental finding on imaging or show symptoms related to obstruction
  • Xray: either normal, infiltrative shadow, hilar mass or lobar collapse
  • CT: mass shadowing, can be PET avid
Radiology Images

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Pedunculated mass

Case Reports
Treatment
  • Endoscopic removal, cryotherapy, fulguration
  • Surgical resection
Gross Description
  • Tan-white, friable, pedunculated / polypoid, smooth to verrucoid, glistening
  • Wart-like, cauliflower-like
  • Generally less than a few centimeters in size
Micro Description
  • Usually exophytic, papillary lesion with arborizing fibrovascular cores lined by keratinizing or nonkeratinizing mature squamous epithelium
  • Rarely inverted pattern
  • Lesion may grow into adjacent alveolar spaces
  • May contain areas lined by ciliated or non-ciliated columnar cells with cuboidal cells or mucin-filled cells (mixed squamous and glandular papilloma)
  • May exhibit viral cytopathic effect: enlarged hyperchromatic nuclei, nuclear wrinkling, polychromasia, binucleate forms, perinuclear halos
  • Mild to moderate stromal inflammation which may be related to airway obstruction
  • No mitoses, no necrosis
Micro Images

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Images c/o Roseann Wu, M.D.



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Various images

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Solid mass

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Schneiderian papilloma

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Bronchial papilloma

Cytology Description
  • Moderate cellularity, single and loosely clustered squamous cells
  • Cytoplasmic keratinization and dark pyknotic nuclei with variable atypia, may show cells resembling koilocytes
  • Background acute inflammation
Cytology Images

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Cytomorphology

Positive Stains
Negative Stains
Molecular / Cytogenetics Description
  • Subset positive for HPV by ISH or PCR
Differential Diagnosis
Additional References