Case 210 - Discussion

Uploaded: 2008-05-05, Updated: 2008-07-12

Anaplastic (Undifferentiated) Carcinoma of Thyroid

The Key Features

 

CLINICAL FEATURES

  • 2-5% of all thyroid carcinomas, more prevalent in areas where goiter is endemic.

  • Mean age 70 years, M:F=1:1.1-1.2.

  • Clinical presentations: rapid growth or sudden enlargement of a long standing goiter, often associated with hoarseness, vocal cord paralysis, dysphagia and pain.

GROSS FINDINGS

 

MICROSCOPIC FINDINGS

  • Highly pleomorphic epithelioid, spindle and giant cells.

  • Coagulative necrosis, frequent mitoses, commonly extensive neutrophilic infiltrate and aggregate.

  • Characteristic vascular permeation with tumor obliteration of the vascular lumen.

  • With adequate sampling, 50-90% cases contain differentiated thyroid carcinoma.

SUBTYPES

  • Angiomatoid subtype

  • Osteoclast subtype

  • Rhabdoid subtype

  • Lymphoepithelioma-like

  • Paucicellular subtype

  • Carcinosarcoma subtype

  • Adenosquamous subtype

  • Squamous cell carcinoma subtype

DIFFERENTIAL DIAGNOSES

  • Angiosarcoma: usually epithelioid cells with binucleation, rare multinucleated giant cells; positive for CD31, CD34, and factor VIII.

  • Reidel thyroiditis: dense sclerotic inflammation, lack of pleomorphism, atypical mitoses or ghosted vessels.

IMMUNOHISTOCHEMISTRY AND SPECIAL STAINS

  • Cytokeratin 40-100%

  • EMA 50%

  • Vimentin 50-100%

  • P53 70%

  • Thyroglobulin and TTF-1 usually negative, except the residual differentiated carcinoma

  • Negative for calcitonin, HMB45, neuroendocrine markers

ELECTRON MICROSCOPIC FINDINGS

 

CYTOGENETIC STUDIES

 

TREATMENT AND PROGNOSIS

  • 50% of cases are inoperable with regional lymph node or distant metastasis.

  • Most patients survive less than one year, mean survival 4-6 months.

REFERENCES