Lung tumor
Other carcinoma
Squamous cell carcinoma

Author: Deepali Jain, M.D. (see Authors page)

Revised: 27 December 2016, last major update September 2012

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

PubMed Search: squamous cell carcinoma[title] lung
Cite this page: Squamous cell carcinoma. website. Accessed April 22nd, 2018.
Definition / general
  • Carcinoma arising from squamous epithelial cells, morphologically characterized by proliferation of atypical, often pleomorphic squamous cells; graded as well, moderately, or poorly differentiated; well differentiated carcinomas are usually associated with keratin production and presence of intercellular bridges between adjacent cells; subtypes include basaloid, clear cell type, papillary, small cell nonkeratinizing (WHO)
  • Early lung carcinoma of hilar type:
    • Arises proximal to sub segmental bronchi (i.e. major bronchi), confined to bronchial wall with no lymph node metastases
    • Usually squamous cell carcinoma; may be polypoid, nodular, superficially infiltrating or mixed
    • Longitudinal mucosal folds show changes at tumor border
    • Superficial tumor has thickened and fused folds
    • Five year survival is 90% or more if no second squamous cell carcinoma present

  • Early squamous cell carcinoma of peripheral type:
    • Defined as tumor 2 cm or less in peripheral lung with no lymph node or distal metastases
    • Only rarely identified in practice, since these tumors grow rapidly
    • Often have glandular cell characteristics

  • Basaloid squamous cell carcinoma:
    • Very aggressive subtype

  • Spindle cell squamous cell carcinoma:
    • Also called sarcomatoid carcinoma
Gross description
  • Usually central portion of lung affecting larger bronchi but may be peripheral
  • Invades peribronchial soft tissue, lung parenchyma and nearby lymph nodes
  • May compress pulmonary artery and vein
  • Peripheral tumors often have nodular growth with central necrosis and cavitation
  • Surrounding lung may exhibit lipid pneumonia, bronchopneumonia, atelectasis
  • Calcification is unusual
Gross images

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Central cavitation

Tumor obstructing bronchus

Tumor extending to pleura

Microscopic (histologic) description
  • Sheets or islands of large polygonal malignant cells containing keratin (individual cells or keratin pearls) and intercellular bridges
  • Adjacent bronchial dysplasia or carcinoma in situ is common
  • At advancing tumor border, tumor cells usually destroy alveoli or fill alveolar spaces
  • Rarely spreads beneath basement membrane
  • May have focal areas of intracytoplasmic mucin
  • Rarely oncocytes, foreign body giant cells (reacting to keratin), pallisading granulomas, extensive neutrophilic infiltration, lepidic growth pattern at tumor periphery, clear cell change (glycogen)
  • Classify as well, moderately or poorly differentiated based on amount of keratinization present in predominant component
  • Peripheral tumor types: alveolar space filling (tumor cells fill alveoli but don’t destroy elastic septa), expanding type (growth destroys elastic septa) or mixture
  • Subtypes: basaloid, clear cell (numerous clear tumor cells containing glycogen), small cell (small tumor cells with focal keratinization, distinct nucleoli, sharply outlined tumor nests, less necrosis than small cell neuroendocrine carcinoma), papillary
  • Important to examine margins carefully for intraepithelial spread
Microscopic (histologic) images

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Well differentiated

Moderately differentiated

Mixed, with keratin pearls and mitotic figures

Virtual slides

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Cavitating tumor

Endobronchial and bronchial tumors

Keratinizing-moderately differentiated

Esophageal metastasis

Cytology description
  • Often positive in sputum
Positive stains
Negative stains
  • Vimentin (usually), TTF1 (usually), Napsin A
Electron microscopy description
  • Abundant tonofilaments, complex desmosomes, basal lamina
Differential diagnosis