Follicular thyroid carcinoma

From Libre Pathology
Jump to navigation Jump to search
Follicular thyroid carcinoma
Diagnosis in short

Micrograph showing a follicular thyroid carcinoma. H&E stain.

LM bland thyroid cells invading through the (fibrous) capsule or lymphovascular invasion or distal metastases
LM DDx follicular thyroid adenoma, papillary thyroid carcinoma follicular variant
Site thyroid gland

Signs thyroid nodule/mass
Prevalence uncommon, female predominant
Prognosis good
Treatment surgical excision

Follicular thyroid carcinoma, abbreviated FTC, is an uncommon malignancy of the thyroid gland. It is also known as follicular carcinoma.


  • Usually spread by the hematologic route.
    • PTC usually spreads via lymphatics.


Medical school memory device 4 Fs:

  • FNA NOT diagnosable.
  • Far away mets (sometimes).
  • Female predominant.
  • Favourable prognosis.


  • Encapuslated lesion +/-evidence of invasion through the capsule.




  • Defined by either:
    1. Invasion through the capsule:
      • Should be all the way through.[1]
        • 1/2 does not count.
        • Fibrous reaction does not count.
        • "Above the contour" does not count.
    2. Vascular invasion (all of the following):
      1. In a small vein (not a capillary), that is outside of the tumour mass.
      2. Tumour adherent to the side of the vessel.
      3. Tumour must be re-endothelialized.


  • Impossible to differentiate from follicular adenoma on FNA (no cytologic differences).
  • Described as "over-diagnosed" ... misdiagnoses: PTC follicular variant, follicular adenoma, multinodular goitre with a thick capsule.




See also


  1. SR. 17 January 2011.
  2. Sobrinho-Simões, M.; Eloy, C.; Magalhães, J.; Lobo, C.; Amaro, T. (Apr 2011). "Follicular thyroid carcinoma.". Mod Pathol 24 Suppl 2: S10-8. doi:10.1038/modpathol.2010.133. PMID 21455197.