Thyroid gland
Other carcinoma
Anaplastic carcinoma

Author: Shahidul Islam, M.D., Ph.D. (see Authors page)

Revised: 1 February 2017, last major update March 2009

Copyright: (c) 2003-2017,, Inc.

PubMed Search: anaplastic carcinoma thyroid

Related Topics: Paucicellular variant, Rhabdoid variant
Cite this page: Anaplastic carcinoma. website. Accessed December 14th, 2017.
Definition / general
  • Undifferentiated (high grade) carcinoma of thyroid gland
  • 2% of thyroid cancers but 40% of thyroid cancer deaths
  • Rapidly enlarging, bulky neck mass invades adjacent structures causing hoarseness, dysphagia, dyspnea
  • Most thyroid sarcoma-like tumors are probably anaplastic carcinomas; small cell types reported in past were probably lymphoma or variants of medullary or insular carcinoma (Am J Clin Pathol 1985;83:135)
  • Also called undifferentiated carcinoma, carcinosarcoma, sarcomatoid carcinoma
  • Mean age 65 years, 75% in women
  • Probably arises as anaplastic transformation of papillary, follicular or Hürthle cell carcinoma; most cases have a core of conserved mutations in well differentiated and anaplastic areas, plus increases in mutation rates in anaplastic areas (Am J Surg Pathol 2003;27:1559)
Clinical features
  • 50% have prior multinodular goiter, 20% have prior differentiated carcinoma, 20% have concurrent differentiated carcinoma
Radiology images

Images hosted on PathOut server:

CT scan, contributed by Dr. Mark R. Wick

Case reports
Gross description
  • Large solid tumor with necrosis and hemorrhage that invades adjacent structures
Gross images

Images hosted on PathOut server:

Contributed by Dr. Mark R. Wick

AFIP Images:

Scant residual thyroid

Metastases to stomach with ulcerated center

Images hosted on other servers:

Encapsulated tumor with focal necrosis

Large necrotic tumor

Nodular tumor

Solid and cystic tumor

Microscopic (histologic) description
  • Three patterns:
    • Large, pleomorphic giant cells resembling osteoclasts with cellular connective tissue septa, may have cavernous blood filled sinuses resembling aneurysmal bone cyst (Am J Surg Pathol 1991;15:160)
    • Spindle cells resembling sarcoma
    • Squamoid cells that are relatively undifferentiated but also appear epithelial with occasional focal keratinization
  • Patterns are often mixed with better differentiated cells palisading at necrotic edges and with precursor well differentiated carcinoma; necrosis
  • Vascular invasion and mitotic figures are common
  • Rarely has rhabdoid inclusions (Am J Surg Pathol 2007;31:729)
Microscopic (histologic) images

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Images hosted on PathOut server:

Contributed by Dr. Mark R. Wick

Contributed by Dr. Stephen J. Schultenover, Vanderbilt University, Tennessee:

Spindled tumor

AE1 / AE3


AFIP Images:

Squamoid differentiation with central necrosis

Elongated spindle cells

Storiform pattern resembles MFH

Hemangiopericytoma-like growth pattern

Focally prominent myxoid pattern and extensive inflammation

Diffuse infiltration into perithyroidal fat, resembling lymphoma

Bone formation

Giant cells (AFIP):

Numerous giant cells

Bizarre nucleated tumor giant cells

Numerous osteoclast-like giant cells

Spread / Metastases (AFIP):

Direct invasion of trachea

Metastasis in wall of colon

Metastases to lung


Keratin stains many mesenchymal-like tumor cells (AFIP)

Focal CEA staining (AFIP)

Thyroglobulin stains

Fibrosing variant,
keratin stain,
contributed by
Dr. Mark R. Wick

Transformation from well differentiated to undifferentiated carcinoma (AFIP):

Spindled pattern with residual papillary carcinoma

Follicular carcinoma (left), anaplastic component (right)

Insular component (left), cartilaginous features (right)

Various images

Vascular invasion (AFIP):

Tumor invades wall of vein

Tumor thrombus in partially calcified artery

Intravascular tumor thrombus

Images hosted on other servers:

Large pleomorphic tumor cells

Pleomorphic and hyperchromatic cells

Partially necrotic tumor

With osteoclast-like giant cells

Arising from papillary carcinoma

Cytology description
  • Giant cell subtype has large, bizarre cells with prominent nucleoli, spindle cell type has spindled cells and necrotic debris
Cytology images

Images hosted on other servers:

Bizarre tumor giant cells

Atypical cells

Giant cell type has large, bizarre cells

Spindle cell type has dyscohesive spindled cells

Positive stains
Electron microscopy description
Electron microscopy images

Images hosted on PathOut server:

AFIP Images:

Tumor cells appear extremely primitive

Retention of microvilli

Molecular / cytogenetics description
Additional references