Table of Contents
Definition / general | Diagnosis | Prognostic factors | Case reports | Microscopic (histologic) description | Microscopic (histologic) images | Virtual slides | Cytology description | Cytology images | Positive stains | Molecular / cytogenetics description | Differential diagnosis | Additional referencesCite this page: Islam S. Papillary carcinoma - follicular variant. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/thyroidfollicularvariant.html. Accessed December 6th, 2019.
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)
Diagnosis
- Suggested to classify encapsulated tumors separately due to their superior prognosis (Cancer 2006;107:1255)
- Recommended to diagnose equivocal cases as well differentiated thyroid tumor of uncertain malignant potential (Int J Surg Pathol 2000;8:181)
- Experts often disagree on diagnosis (Am J Clin Pathol 2008;130:736)
Prognostic factors
- Same prognosis as typical papillary carcinoma (Arch Surg 2003;138:1362, Cancer 2003;97:1181)
Case reports
- 22 year old woman with extension to parapharyngeal space (BMC Ear Nose Throat Disord 2006;6:3)
- 46 year old man presenting with pleural effusion (Acta Cytol 2007;51:911)
- 56 year old man with glomeruloid growth pattern (Hum Pathol 2008;39:1540)
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.
Contributed by Mark R. Wick, M.D.
Images from AFIP:
Images hosted on other servers:
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:



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
Positive stains
Molecular / cytogenetics description
- 25 - 43% have Ras mutations, 3 - 42% have RET / PTC rearrangements (Am J Clin Pathol 2003;120:71, Hum Pathol 2006;37:824)
- May have PAX8-PPARgamma rearrangement of follicular tumors (J Clin Endocrinol Metab 2006;91:213)
- Only 13% have BRAF mutation (Hum Pathol 2009;40:827)
Differential diagnosis
Additional references
Advertisement