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  Table of Contents    
ORIGINAL ARTICLE  
Year : 2018  |  Volume : 61  |  Issue : 3  |  Page : 380-382
Noninvasive follicular thyroid neoplasm with papillary-like nuclear features: A distinct clinicopathologic entity


1 Department of Pathology and Laboratory Medicine, Basavatarakam Indo American Cancer Hospital and Research Institute, Hyderabad, Telangana, India
2 Department of Surgical Oncology, Basavatarakam Indo American Cancer Hospital and Research Institute, Hyderabad, Telangana, India

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Date of Web Publication13-Jul-2018
 

   Abstract 


Objective: The objective of this study is to retrospectively evaluate follicular variant of papillary thyroid carcinoma (FVPTC) and reclassify encapsulated FVPTC as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) according to the criteria proposed by The Endocrine Pathology Society working group in 2015 to correlate with outcome. Materials and Methods: Retrospective review of case records of all patients diagnosed as carcinoma of thyroid between 2015 and 2016 was done for the histologic subtype. Gross and microscopic features on resected specimens of FVPTC were reviewed and subtyped as invasive and encapsulated based on capsular/vascular invasion; the encapsulated forms were further studied for size, number, follicular architecture, nuclear features, presence of psammoma bodies, stromal fibrosis, necrosis, mitoses, and lymph node status. Results: Out of the 383 patients with thyroid carcinomas in the study period, 349 were PTC which included 106 FVPTC. Thirty-three patients fulfilled the criteria to be labeled as NIFTP. Total thyroidectomy was performed in 8 patients and hemithyroidectomy in 25 patients. Lymph node dissection along with total thyroidectomy was done in 3 and completion thyroidectomy following hemithyroidectomy was done in 9. There were 29 single and 4 multiple lesions with size varying from 0.2 to 7 cm including 5 lesions measuring <1 cm. The involvement was confined to one lobe in 31 and both lobes in 2 specimens. Patients are on follow-up with no recurrence till date. Conclusion: Thyroid carcinomas currently diagnosed as FVPTC should be evaluated for criteria of NIFTP to avoid overtreatment as they have an indolent behavior.

Keywords: Encapsulated follicular variant of papillary thyroid carcinoma, indolent behavior, noninvasive follicular thyroid tumor with papillary-like nuclear features, revised nomenclature

How to cite this article:
Fonseca D, Bhuyan S, Murthy SS, Rao V, Rao C, N. Raju K V, Sundaram C. Noninvasive follicular thyroid neoplasm with papillary-like nuclear features: A distinct clinicopathologic entity. Indian J Pathol Microbiol 2018;61:380-2

How to cite this URL:
Fonseca D, Bhuyan S, Murthy SS, Rao V, Rao C, N. Raju K V, Sundaram C. Noninvasive follicular thyroid neoplasm with papillary-like nuclear features: A distinct clinicopathologic entity. Indian J Pathol Microbiol [serial online] 2018 [cited 2019 Dec 10];61:380-2. Available from: http://www.ijpmonline.org/text.asp?2018/61/3/380/236598





   Introduction Top


Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy accounting for 80% of thyroid carcinomas.[1] Several variants of PTC are described, and follicular variant of PTC (FVPTC) is one of the common variants and comprises 20%–30% of PTC. It is characterized by follicular growth pattern and cells lining follicles having nuclear features of PTC.[1] The FVPTC is not a homogeneous group and can be divided into two groups based on morphology: infiltrative and encapsulated types. A significant difference was noted in clinical behavior and potential therapeutic implications between the two groups.[2],[3] The infiltrating subgroup has metastatic potential like the classic PTC whereas the encapsulated variant behaves like follicular adenoma (FA) with indolent behavior even after lobectomy.[3],[4],[5] An international multidisciplinary group of thyroid specialists, after extensive evaluation of the encapsulated/noninvasive cases with outcome data, issued the term noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) and developed a set of inclusion criteria.[3],[4],[6] The evaluation can be done on hematoxylin and eosin (H and E) stained sections.

In the present study, we aim to re-designate the encapsulated FVPTC as NIFTP based on morphology according to the established consensus diagnostic criteria proposed by Nikiforov et al.[3] We also aim to document its frequency in patients diagnosed as FVPTC and correlate with outcome.


   Materials and Methods Top


This was a retrospective observational study of all the PTC diagnosed on resected specimens during 2015–2016. The patients diagnosed on fine-needle aspiration cytology (FNAC)/cell block/core needle biopsies were excluded from the study. The demographic and clinical data were obtained from records. Serological data were collected wherever available.

The clinical presentation as a thyroid mass and/or lymph nodal mass, status of thyroid function, and presence of metastases if any, were noted. Family history and exposure to drugs/radiation were noted. Diagnosis made on FNAC/cell block/core biopsies if present, was noted.

The type of thyroidectomy, presence of lesion as single/multiple; size; unilateral/bilateral; color/texture; areas of hemorrhage, necrosis, cystic change if any; encapsulation/circumscription were noted on the gross specimen. H and E stained sections were evaluated for the following features: encapsulated or well demarcated; predominant pattern; nuclear features of PTC; presence of psammoma bodies; presence of necrosis and mitoses; and capsular and/or vascular invasion. Immunohistochemistry was not done for routine workup of the cases.[7] Adjacent thyroid was examined for the presence of lymphocytic/Hashimoto's thyroiditis. If lymph node dissection was done, their number/involvement was noted.

The lesions were classified as NIFTP according to the criteria proposed, and follow-up details were correlated with disease-free survival.[3]


   Results Top


There were 383 patients diagnosed as carcinoma thyroid on resected specimens in the study period with 349 as PTCs including 106 FVPTC. Thirty-three patients fulfilled the criteria to be labeled as NIFTP. There were 23 females and 10 males with age ranging from 17 to 65 (median 37.06) years. All patients presented with swelling in the neck which was moving with deglutition. Elevated thyroid stimulating hormone was seen in 7 patients and elevated thyroxin 3/4 in 3 patients. There was no family history of any malignancy or exposure to drugs/radiation. FNAC was available in 12 patients and reported as PTC in 9 patients.

Pathology

The resected specimens included 8 total thyroidectomies and 25 hemithyroidectomies. Lymph node dissection along with total thyroidectomy was done in 3 and completion thyroidectomy following hemithyroidectomy was done in 9. There were 29 single and 4 multiple lesions with size varying from 0.2 to 7 cm including 5 lesions measuring <1 cm. The involvement was confined to one lobe in 31 and both lobes in 2 specimens. All the lesions, single/multiple were well encapsulated with thin capsule and no invasion. The lesion(s) were gray-white with no areas of hemorrhage, cystic change, or necrosis [Figure 1]. Microscopically, all lesions were encapsulated with follicular pattern. PTC like nuclear features including nuclear grooves, clearing, and ground glass appearance was seen in all cases. There were no papillary processes/psammoma bodies [Figure 1]. Completion thyroidectomy specimens (9) did not show additional lesions. Adjacent thyroid was normal in 31 and showed lymphocytic thyroiditis in 2. Lymph node dissection was done in 3 and none showed metastases. There was no evidence of distant metastases either. All the lesions were diagnosed as encapsulated FVPTC and only 4 were labeled as NIFTP after the term was introduced.
Figure 1: (a) Gross specimen of hemithyroidectomy showing a well-circumscribed gray-white nodule. (b) Photomicrograph showing an encapsulated follicular patterned lesion with no capsular and/or vascular invasion. Inset shows the nuclear features of papillary carcinoma thyroid

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Patients were deferred for completion/total thyroidectomy/lymph node dissection when the diagnosis was made on hemithyroidectomy in 16 patients. None of the patients received radioiodine therapy. Follow-up was available for all patients with a period varying from 6 to 24 months, and all were disease free at last follow-up.


   Discussion Top


PTC has several morphological variants, and several studies emphasized the variants with aggressive behavior.[1] The prognosis of FVPTC is considered similar to classical PTC.[1] According to TNM staging lymph node metastases, extrathyroidal extension and distant metastases are associated with higher stage.[1] The encapsulated or noninvasive FVPTC is shown to be associated with indolent behavior with minimal risk of recurrence and metastases.[1],[2],[3],[4],[5]

The diagnosis of FVPTC is usually made on the nuclear features, and it needs to be differentiated from other follicular patterned lesions.[2] In addition to growth pattern and nuclear features, the encapsulation and circumscription characterize the NIFTP. The subtype identification of FVPTC is not routinely done, and the implications of the subtyping are not highlighted earlier. In our study, we identified NIFTP in 33/106 (31.13%) patients diagnosed as FVPTC and all were disease free on follow-up. There were 5 lesions measuring <1 cm in our study. Papillary micro-carcinoma was considered in the differential diagnosis. Papillary microcarcinoma occurs in adults (>19 years), in the periphery of the lobe, measures <1 cm, and usually asymptomatic with indolent behavior.[2],[4] Microscopically, it may show any growth pattern (papillary/follicular), and associated with psammoma bodies and stromal fibrosis.[2] All our cases were encapsulated with follicular growth pattern with no psammoma bodies and stromal fibrosis, thus qualifying to be labeled as NIFTP. Radical surgery was done in 17/32 (53.13%) of our patients before the entity of NIFTP was recognized; however, none of the patients had evidence of extrathyroidal extension, lymph node, or distant metastases. Sixteen of the patients who were diagnosed on hemithyroidectomy specimens were deferred radical surgery, and none developed recurrence or metastases on follow-up.

FVPTC shares some morphologic and molecular features with both PTC and follicular carcinoma (FC).[2],[3],[4] Molecular analysis has demonstrated that these lesions are driven by clonal genetic alterations and hence are neoplastic.[3] These tumors do not show BRAF V600E mutations which are associated with classic PTC rather they show a high prevalence of RAS and other mutations which are associated with follicular patterned tumors such as FA, FC, and encapsulated follicular variant of PTC.[3]

Papillary thyroid carcinoma has excellent prognosis with more than 90% survival at 20 years. Risk of recurrence and distant metastases are reported in <10% of cases.[1] It is important to use the term NIFTP in the routine reporting as they do not require immediate completion thyroidectomy and radioactive iodine therapy.[3],[5],[8]

FNAC is an initial modality for diagnosis of PTC. However, a total thyroidectomy and/or lymph node dissection following FNAC diagnosis results in radical surgery for an indolent tumor-like NIFTP. It is recommended to correlate with imaging studies and clinical evidence of local and/or lymph node involvement before a radical surgery, to avoid overtreatment of an indolent tumor.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
LiVolsi VA. Papillary thyroid carcinoma: An update. Mod Pathol 2011;24 Suppl 2:S1-9.  Back to cited text no. 1
    
2.
Moghaddam PA, Virk R, Sakhdari A, Prasad ML, Cosar EF, Khan A, et al. Five top stories in thyroid pathology. Arch Pathol Lab Med 2016;140:158-70.  Back to cited text no. 2
    
3.
Nikiforov YE, Seethala RR, Tallini G, Baloch ZW, Basolo F, Thompson LD, et al. Nomenclature revision for encapsulated follicular variant of papillary thyroid carcinoma: A Paradigm shift to reduce overtreatment of indolent tumors. JAMA Oncol 2016;2:1023-9.  Back to cited text no. 3
    
4.
Thompson LD. Update on follicular variant of papillary thyroid carcinoma with an emphasis on new terminology: Noninvasive follicular thyroid neoplasm with papillary like nuclear features. Diagn Histopathol 2016;22:171-8.  Back to cited text no. 4
    
5.
Thompson LD. Ninety-four cases of encapsulated follicular variant of papillary thyroid carcinoma: A name change to noninvasive follicular thyroid neoplasm with papillary-like nuclear features would help prevent overtreatment. Mod Pathol 2016;29:698-707.  Back to cited text no. 5
    
6.
Poller DN, Nikiforov YE. Non-invasive follicular thyroid neoplasm with papillary-like nuclei: Reducing overtreatment by reclassifying an indolent variant of papillary thyroid cancer. J Clin Pathol 2016. pii: jclinpath-2016-203930.  Back to cited text no. 6
    
7.
Chernock RD. Immunohistochemistry of thyroid gland carcinomas: Clinical utility and diagnostic pitfalls. Diagn Histopathol 2016;22:184-90.  Back to cited text no. 7
    
8.
Rosario PW. Ultrasonography and cytology as predictors of noninvasive follicular thyroid (NIFTP) neoplasm with papillary-like nuclear features: Importance of the differential diagnosis with the invasive encapsulated follicular variant of papillary thyroid cancer. Clin Endocrinol (Oxf) 2017;87:635-6.  Back to cited text no. 8
    

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Correspondence Address:
Daphne Fonseca
Department of Lab Medicine, Basavatarakam Indo American Cancer Hospital and Research Institute, Hyderabad, Telangana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/IJPM.IJPM_185_17

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