Thyroid gland
Papillary thyroid carcinoma
Follicular patterned

Topic Completed: 1 March 2009

Minor changes: 16 July 2020

Copyright: 2003-2018,, Inc.

PubMed Search: papillary carcinoma thyroid follicular

See also: Diffuse follicular variant, Encapsulated follicular variant

Shahid Islam, M.D., Ph.D.
Page views in 2019: 11,718
Page views in 2020 to date: 5,936
Cite this page: Islam S. Follicular. website. Accessed August 6th, 2020.
Definition / general
  • Papillary carcinoma composed almost completely of follicles, with classic papillary nuclear features
  • First described in 1977 (Am J Surg Pathol 1977;1:123)
  • Metastases are usually nodal, not distant, with classic papillary features
  • Metastatic tumor to tumor lesions may simulate a thyroid primary (Arch Pathol Lab Med 1999;123:703)
Prognostic factors
Case reports
Microscopic (histologic) description
  • Wide fibrous bands incompletely divide tumor into lobules
  • Follicular architecture but papillary cytology
  • Usually infiltrative with fibrous trabeculation, psammoma bodies, strongly eosinophilic colloid with scalloping
  • Important diagnostic criteria include pseudoinclusions (cytoplasmic invaginations into nucleus), abundant nuclear grooves, ground glass nuclei (Am J Surg Pathol 2004;28:1336); also nuclear clearing, nuclear overlapping and crowding, nuclear enlargement
Microscopic (histologic) images

Images hosted on PathOut server:

Contributed by Andrey Bychkov, M.D., Ph.D.

Bone fragment surrounded by tumor

Developing bone marrow

Infiltrative growth, follicular pattern, bright colloid

Oncocytic PTC:
eosinophilic cyto-
plasm, nuclei,

Vesicular nuclei with irregular membranes

Evident major and minor diagnostic features

"Minor diagnostic
features" include dark
colloid with frequent
scalloping and clefting

Contributed by Mark R. Wick, M.D.

Various Images

Images from AFIP:

Wide fibrous bands

Microfollicular and macrofollicular patterns

formations re-
semble nodular

Clear cytoplasm

Nuclei are overlapping with empty appearance

Some neoplastic follicles lined by granular acidophilic cells

Clear cell change

Intraluminal colloid

Follicular pattern of papillary carcinoma at bottom

Various images

Images hosted on other servers:

Follicular epithelial cells have ground glass nuclei and occasional nuclear grooves

Vesicular nuclei and hemorrhage in follicular lumina

Crowded nuclei and scalloped colloid

Collision tumor with squamous cell carcinoma

Virtual slides

Images hosted on other servers:

Van Gieson

Cytology description
  • Increased cellularity, moderate thin watery colloid with variable eosinophilic colloid
  • Cells are in sheets, small acini or syncytial fragments
  • Nuclear enlargement, but may lack prominent nuclear features of papillary carcinoma (Am J Clin Pathol 1999;111:216)
  • Highly suggestive if syncytial clusters, microfollicular architecture, chromatin clearing and nuclear grooves (Acta Cytol 2006;50:663)
  • Ultrafast Papanicolaou stained smears makes clear nuclei more conspicuous (Cancer 2006;108:174)
Cytology images

Images hosted on other servers:

Cellular aspirates
with some micro-
follicular aggre-
gates, no colloid

Acinar arrangement with intranuclear inclusion

Fig. 1 (left): Ovoid and pear shaped hypochromatic nuclei and nuclear grooves; cells show nuclear
overlap, round / oval hypochromatic nuclei, eccentric small nucleoli, and nuclear grooves (arrow)
Fig. 2 (center): Cells have powdery chromatin, nuclear grooves and intranuclear cytoplasmic inclusions
Fig. 3 (right): Enlarged round / oval nuclei, but papillary nuclear features are difficult to appreciate

Molecular / cytogenetics description
Additional references
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