Thyroid & parathyroid

Other uncommon thyroid carcinomas

Squamous cell carcinoma

Last author update: 1 September 2016
Last staff update: 16 August 2023

Copyright: 2002-2024,, Inc.

PubMed Search: squamous cell carcinoma thyroid

Shuanzeng (Sam) Wei, M.D., Ph.D.
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Cite this page: Wei S. Squamous cell carcinoma. website. Accessed June 16th, 2024.
Definition / general
  • Considered a variant of anaplastic thyroid carcinoma in the 2022 WHO
  • Very rare, highly lethal thyroid carcinoma with pure squamous component
  • Clinically and pathologically shares features with anaplastic thyroid cancers; can be regarded as a variant of anaplastic thyroid carcinoma
  • Must rule out:
    • Metastasis or direct invasion of squamous cell carcinoma from oropharynx, larynx, trachea, lung, other organs
    • Papillary carcinoma with foci of squamous differentiation (occurs in 15 to 45% of papillary carcinomas)
    • Anaplastic thyroid carcinoma with squamous differentiation
    • Other thyroid carcinomas with squamous differentiation, including mucoepidermoid carcinoma, sclerosing mucoepidermoid carcinoma with eosinophilia, CASTLE
Essential features
  • Squamous cell carcinoma is regarded as a variant of anaplastic thyroid carcinoma
  • Aggressive clinical behavior
  • Similar to anaplastic carcinoma, affects older patients with chronic goiter
Clinical features
  • Older patients present with a rapidly enlarging neck mass
  • Patients may have a long history of preexisting thyroid disease
  • Extrathyroidal extension and cervical nodal metastases are common, distant metastases are rare
Prognostic factors
  • Poor prognosis with median survival < 6 months
  • Death in almost all cases, usually due to local progression (Int Semin Surg Oncol 2007;4:8) or airway compression
Case reports
  • Radical resection and radiation (often radioresistant)
Clinical images

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Mass pressuring;
infiltrating trachea;
surrounding soft tissue

Gross description
  • Firm infiltrating mass with necrosis
Gross images

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Enlarged left lobe

White tumor with central necrosis

Microscopic (histologic) description
  • Invasive squamous carcinoma, with or without keratinization
  • High mitotic index
  • Extrathyroid, vascular and perineural invasions are common
Microscopic (histologic) images

Contributed by Shuanzeng Wei, M.D., Ph.D.

Squamous cell carcinoma with necrosis

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Infiltrating squamous cell carcinoma

Cytology images

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Atypical squamoid cell

Positive stains
Differential diagnosis
  • CASTLE: circumscribed, slowly growing tumor, CD5+, CD117+
  • Metastasis or direct invasion of squamous cell carcinoma from other organs: history of squamous cell carcinoma, PAX8-
  • Papillary thyroid carcinoma with squamous differentiation: squamous component is small portion of the well differentiated thyroid carcinoma
  • Squamous metaplasia: benign squamous cells
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