Seven years of Non-invasive Follicular Thyroid Neoplasm with Papillary-like Nuclear Features (NIFTP): Rate of Acceptance and Variation of Diagnostic Approaches Across Different Continents.

CONTEXT: Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) was introduced as a new entity replacing the diagnosis of noninvasive encapsulated follicular variant of papillary thyroid carcinoma (PTC). Significant variability in the incidence of NIFTP diagnosed in different world regions has been reported. OBJECTIVE: To investigate the rate of adoption of NIFTP, change in practice patterns, and uniformity in applying diagnostic criteria among pathologists practicing in different regions. METHODS: Two surveys distributed to pathologists of the International Endocrine Pathology Discussion Group with multiple-choice questions on NIFTP adoption into pathology practice and whole slide images of 5 tumors to collect information on nuclear score and diagnosis. Forty-eight endocrine pathologists, including 24 from North America, 8 from Europe, and 16 from Asia/Oceania completed the first survey and 38 the second survey. RESULTS: A 94% adoption rate of NIFTP by the pathologists was found. Yet, the frequency of rendering NIFTP diagnosis was significantly higher in North America than in other regions (P = .009). While the highest concordance was found in diagnosing lesions with mildly or well-developed PTC-like nuclei, there was significant variability in nuclear scoring and diagnosing NIFTP for tumors with moderate nuclear changes (nuclear score 2) (case 2, P < .05). Pathologists practicing in North America and Europe showed a tendency for lower thresholds for PTC-like nuclei and NIFTP than those practicing in Asia/Oceania. CONCLUSION: Despite a high adoption rate of NIFTP across geographic regions, NIFTP is diagnosed more often by pathologists in North America. Significant differences remain in diagnosing intermediate PTC-like nuclei and respectively NIFTP, with more conservative nuclear scoring in Asia/Oceania, which may explain the geographic differences in NIFTP incidence.

Performance of a multigene genomic classifier and clinical parameters in predicting malignancy in a Southeast Asian cohort of patients with cytologically indeterminate thyroid nodules.

BACKGROUND: Most thyroid nodules are benign. It is important to determine the likelihood of malignancy in such nodules to avoid unnecessary surgery. The primary objective of this study was to characterize the genetic landscape and the performance of a multigene genomic classifier in fine-needle aspiration (FNA) biopsies of cytologically indeterminate thyroid nodules in a Southeast Asian cohort. The secondary objective was to assess the predictive contribution of clinical characteristics to thyroid malignancy. METHODS: This prospective, multicenter, blinded study included 132 patients with 134 nodules. Molecular testing (MT) with ThyroSeq v3 was performed on clinical or ex-vivo FNA samples. Centralized pathology review also was performed. RESULTS: Of 134 nodules, consisting of 61% Bethesda category III, 20% category IV, and 19% category V cytology, and 56% were histologically malignant. ThyroSeq yielded negative results in 37.3% of all FNA samples and in 42% of Bethesda category III-IV cytology nodules. Most positive samples had RAS-like (41.7%), followed by BRAF-like (22.6%), and high-risk (17.9%) alterations. Compared with North American patients, the authors observed a higher proportion of RAS-like mutations, specifically NRAS, in Bethesda categories III and IV and more BRAF-like mutations in Bethesda category III. The test had sensitivity, specificity, negative predictive value, and positive predictive value of 89.6%, 73.7%, 84.0%, and 82.1%, respectively. The risk of malignancy was predicted by positive MT and high-suspicion ultrasound characteristics according to American Thyroid Association criteria. CONCLUSIONS: Even in the current Southeast Asian cohort with nodules that had a high pretest cancer probability, MT could lead to potential avoidance of diagnostic surgery in 42% of patients with Bethesda category III-IV nodules. MT positivity was a stronger predictor of malignancy than clinical parameters.

Neoplasms in Struma Ovarii: A Review.

Struma ovarii is a well-known ovarian teratoma made up of benign thyroid tissue. These lesions demonstrate variable, normal architecture and normal thyroid immunohistochemical staining with positivity for TTF1, PAX8, and thyroglobulin. Though most are benign, some of these lesions can also present with a malignant component. Within this article, we review the most common diagnostic malignancies including papillary thyroid carcinoma, strumal carcinoid, highly differentiated follicular thyroid carcinoma, and other thyroid carcinomas. We additionally review the use of TTF1 staining to assist in differentiating these lesions from surrounding gynecologic epithelium, which is imperative in making such diagnoses. In highlighting these entities, we hope to provide practicing pathologists with an effective and concise review of these lesions to assist in more challenging cases of struma ovarii.

The Cooperative Human Tissue Network of the National Cancer Institute: Supporting Cancer Research for 35 Years.

The Cooperative Human Tissue Network was created by the NCI in 1987 to support a coordinated national effort to collect and distribute high quality, pathologist-validated human tissues for cancer research. Since then, the network has expanded to provide different types of tissue samples, blood and body fluid samples, immunohistologic and molecular sample preparations, tissue microarrays, and clinical datasets inclusive of biomarkers and molecular testing. From inception through the end of 2021, the network has distributed 1,375,041 biospecimens. It served 889 active investigators in 2021. The network has also taken steps to begin to optimize the representation of diverse communities among the distributed biospecimens. In this article, the authors review the 35-year history of this network, describe changes to the program over the last 15 years, and provide operational and scientific highlights from each of the divisions. Readers will learn how to engage with the network and about the continued evolution of the program for the future.

Insights Obtained from the Nontumorous Glandular Tissue in Patients with Endocrine Tumors.

The pathology of neoplasia tends to focus on the tumor that requires characterization, grading, and staging. However, nontumorous tissue surrounding the lesion can also provide information, particularly about pathogenetic mechanisms. In endocrine tissues, this takes the form of precursor lesions that characterize several genetic predisposition syndromes. In addition, because of the unique functional aspects of endocrine neoplasia, the nontumorous tissue provides evidence of hormone excess, with hyperplasia and/or atrophy and other involutional changes allowing the pathologist to confirm both hormone function by the tumor and the effects of medical therapies. In this article, we review the various clinically relevant features that should be assessed and reported to enhance clinical management of patients with endocrine neoplasms. For example, in thyroid there may be inflammatory thyroiditis or goiter of various etiologies; there may be C-cell hyperplasia either as a preneoplastic lesion in patients with genetic predisposition to medullary thyroid carcinoma or as a reactive phenomenon. Drug-induced changes can be seen in thyroid and adrenal cortex. In neuroendocrine tissues, the nontumorous tissues may show precursor lesions such as endocrine cell hyperplasia/dysplasia; there may be related or unrelated hyperplastic or neoplastic lesions. Some tissues, such as pituitary corticotrophs and adrenal cortex, develop changes that reflect feedback suppression by hormone excess that can serve as biomarkers of tumor functionality and provide enhanced clinicopathologic correlates.

The Thyroid Pathologist Meets Therapeutic Pharmacology.

The effects of many pharmacological agents on thyroid function are well known. Direct influences on measurements of thyroid function tests are also described. However, certain classes of drugs produce morphological changes in the gland. This review focuses on the significance of the following drug classes for the thyroid pathologist: iodine, antithyroid drugs, psychotropic drugs, antibiotics, cardiotropic drugs, antidiabetic drugs, and immunomodulatory agents. Radioactive iodine initially induces mild histologic changes; however, the long-term effects include marked follicular atrophy, fibrosis, and nuclear atypia-changes that vary depending on the pre-therapy condition of the gland. Some psychotropic drugs have been associated with a spectrum of inflammatory changes throughout the gland. The tetracycline class of antibiotics, namely minocycline, can lead to a grossly black thyroid gland with pigment seen in both colloid and follicular epithelial cells while variably present within thyroid nodules. The surgical pathologist most commonly sees an amiodarone-affected gland removed for hyperthyroidism, and the histologic findings again depend on the pre-therapy condition of the gland. While GLP-1 receptor agonists carry an FDA black box warning for patients with a personal or family history of multiple endocrine neoplasia or medullary thyroid carcinoma, the C cell hyperplasia originally noted in rats has not borne out in human studies. Finally, thyroiditis and hypothyroidism are well known complications of checkpoint inhibitor therapy, and rare cases of severe thyroiditis requiring urgent thyroidectomy have been reported with unique histologic findings. In this review, we describe the histologic findings for these drugs and more, in many cases including their functional consequences.

Molecular identification of an ETV6-RET fusion in a secretory carcinoma associated with a pleomorphic adenoma.

Pleomorphic adenoma (PA) is the most common neoplasm of the salivary glands. Although several carcinomas have been reported to arise from PA, only 1 case of salivary gland secretory carcinoma (SC) ex pleomorphic adenoma has been previously reported. SC is a newly described salivary gland tumor harboring an ETV6-NTRK3 translocation, which is classically observed in secretory carcinoma of the breast, although other translocations have recently been observed. We report the first case of the molecular identification of a rare ETV6-RET translocation in an SC arising from a PA in the submandibular salivary gland (SC ex PA). Our results add to the diversity of tumors that are associated with PA and contribute to the molecular characterization of SC, which will have implications on its diagnosis, prognosis, and treatment.

Preoperative Identification of Medullary Thyroid Carcinoma (MTC): Clinical Validation of the Afirma MTC RNA-Sequencing Classifier.

Background: Cytopathological evaluation of thyroid fine-needle aspiration biopsy (FNAB) specimens can fail to raise preoperative suspicion of medullary thyroid carcinoma (MTC). The Afirma RNA-sequencing MTC classifier identifies MTC among FNA samples that are cytologically indeterminate, suspicious, or malignant (Bethesda categories III-VI). In this study we report the development and clinical performance of this MTC classifier. Methods: Algorithm training was performed with a set of 483 FNAB specimens (21 MTC and 462 non-MTC). A support vector machine classifier was developed using 108 differentially expressed genes, which includes the 5 genes in the prior Afirma microarray-based MTC cassette. Results: The final MTC classifier was blindly tested on 211 preoperative FNAB specimens with subsequent surgical pathology, including 21 MTC and 190 non-MTC specimens from benign and malignant thyroid nodules independent from those used in training. The classifier had 100% sensitivity (21/21 MTC FNAB specimens correctly called positive; 95% confidence interval [CI] = 83.9-100%) and 100% specificity (190/190 non-MTC FNAs correctly called negative; CI = 98.1-100%). All positive samples had pathological confirmation of MTC, while all negative samples were negative for MTC on surgical pathology. Conclusions: The RNA-sequencing MTC classifier accurately identified MTC from preoperative thyroid nodule FNAB specimens in an independent validation cohort. This identification may facilitate an MTC-specific preoperative evaluation and resulting treatment.

Overview of the 2022 WHO Classification of Thyroid Neoplasms.

This review summarizes the changes in the 5th edition of the WHO Classification of Endocrine and Neuroendocrine Tumors that relate to the thyroid gland. The new classification has divided thyroid tumors into several new categories that allow for a clearer understanding of the cell of origin, pathologic features (cytopathology and histopathology), molecular classification, and biological behavior. Follicular cell-derived tumors constitute the majority of thyroid neoplasms. In this new classification, they are divided into benign, low-risk, and malignant neoplasms. Benign tumors include not only follicular adenoma but also variants of adenoma that are of diagnostic and clinical significance, including the ones with papillary architecture, which are often hyperfunctional and oncocytic adenomas. For the first time, there is a detailed account of the multifocal hyperplastic/neoplastic lesions that commonly occur in the clinical setting of multinodular goiter; the term thyroid follicular nodular disease (FND) achieved consensus as the best to describe this enigmatic entity. Low-risk follicular cell-derived neoplasms include non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), thyroid tumors of uncertain malignant potential, and hyalinizing trabecular tumor. Malignant follicular cell-derived neoplasms are stratified based on molecular profiles and aggressiveness. Papillary thyroid carcinomas (PTCs), with many morphological subtypes, represent the BRAF-like malignancies, whereas invasive encapsulated follicular variant PTC and follicular thyroid carcinoma represent the RAS-like malignancies. This new classification requires detailed subtyping of papillary microcarcinomas similar to their counterparts that exceed 1.0 cm and recommends not designating them as a subtype of PTC. The criteria of the tall cell subtype of PTC have been revisited. Cribriform-morular thyroid carcinoma is no longer classified as a subtype of PTC. The term "Hürthle cell" is discouraged, since it is a misnomer. Oncocytic carcinoma is discussed as a distinct entity with the clear recognition that it refers to oncocytic follicular cell-derived neoplasms (composed of > 75% oncocytic cells) that lack characteristic nuclear features of PTC (those would be oncocytic PTCs) and high-grade features (necrosis and ≥ 5 mitoses per 2 mm2). High-grade follicular cell-derived malignancies now include both the traditional poorly differentiated carcinoma as well as high-grade differentiated thyroid carcinomas, since both are characterized by increased mitotic activity and tumor necrosis without anaplastic histology and clinically behave in a similar manner. Anaplastic thyroid carcinoma remains the most undifferentiated form; squamous cell carcinoma of the thyroid is now considered as a subtype of anaplastic carcinoma. Medullary thyroid carcinomas derived from thyroid C cells retain their distinct section, and there is a separate section for mixed tumors composed of both C cells and any follicular cell-derived malignancy. A grading system for medullary thyroid carcinomas is also introduced based on mitotic count, tumor necrosis, and Ki67 labeling index. A number of unusual neoplasms that occur in the thyroid have been placed into new sections based on their cytogenesis. Mucoepidermoid carcinoma and secretory carcinoma of the salivary gland type are now included in one section classified as "salivary gland-type carcinomas of the thyroid." Thymomas, thymic carcinomas and spindle epithelial tumor with thymus-like elements are classified as "thymic tumors within the thyroid." There remain several tumors whose cell lineage is unclear, and they are listed as such; these include sclerosing mucoepidermoid carcinoma with eosinophilia and cribriform-morular thyroid carcinoma. Another important addition is thyroblastoma, an unusual embryonal tumor associated with DICER1 mutations. As in all the WHO books in the 5th edition, mesenchymal and stromal tumors, hematolymphoid neoplasms, germ cell tumors, and metastatic malignancies are discussed separately. The current classification also emphasizes the value of biomarkers that may aid diagnosis and provide prognostic information.

A benchmark for oncologic outcomes and model for lethal recurrence risk after transoral robotic resection of HPV-related oropharyngeal cancers.

OBJECTIVES: Increasing use of transoral robotic surgery (TORS) is likely to impact outcomes for HPV+ oropharyngeal squamous cell carcinomas (OPSCCs). We aimed to describe oncologic outcomes for a large HPV+ OPSCC cohort after TORS and develop a risk prediction model for recurrence under this treatment paradigm. MATERIALS AND METHODS: 634 HPV+ OPSCC patients receiving TORS-based therapy at a single institution were reviewed retrospectively to describe survival across the entire cohort and for patients suffering recurrence. Risks for distant metastatic recurrence (DMR) and locoregional recurrence (LRR) were modeled using multivariate logistic regression analyses of case-control sub-cohorts. RESULTS: 5-year overall and recurrence-free survival were 91.2% and 86.1%, respectively. 5-year overall survival was 52.5% following DMR and 83.3% after isolated LRR (P = .01). In case-control analyses, positive surgical margins were associated with DMR (adjusted OR 5.8, CI 2.1-16.0, P = .001), but not isolated LRR, and increased DMR risk 4.2 fold in patients with early clinical stage disease. By contrast, LRR was associated with not receiving recommended adjuvant therapy (OR 13.4, CI 6.3-28.5, P < .001). CONCLUSIONS: This study sets a benchmark for oncologic outcomes from HPV+ OPSCC after TORS-based therapy. Under this treatment paradigm, margins are relevant for assessing lethal recurrence risk during clinical trial design and post-treatment surveillance.

TP53 Mutation and Extraneural Metastasis of Glioblastoma: Insights From an Institutional Experience and Comprehensive Literature Review.

Extraneural metastases of glioblastoma (GBM), although rare, are becoming an increasingly recognized occurrence. Currently, the biological mechanism underlying this rare occurrence is not understood. To explore the potential genomic drivers of extraneural metastasis in GBM, we present the molecular features of 4 extraneural metastatic GBMs, along with a comprehensive review and analysis of previously reported cases that had available molecular characterization. In addition to our 4 cases, 42 patients from 35 publications are reviewed. To compare the molecular profiles between GBM cases with extraneural metastasis and the general GBM population, genomic data from GBM samples in The Cancer Genome Atlas (TCGA) database were also analyzed. We found that 64.5% (20/31) of the cases with extraneural metastasis that were tested for TP53 changes had at least 1 TP53 pathogenic variant detected in either 1 or both primary and metastatic tumors. In contrast, TP53 mutation was significantly less frequent in the unselected GBM from TCGA (22.6%, 56/248) (P=0.000). In addition, O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation was more common in unselected TCGA GBM cases (48.6%, 170/350) than in cases with extraneural metastasis (31.8%, 7/22), although not statistically significant. Although isocitrate dehydrogenase (IDH) mutation is a rare occurrence in high-grade astrocytomas, IDH-mutant grade 4 astrocytomas are at least as likely to metastasize as IDH wild-type GBMs; 3 metastatic cases definitively harbored an IDH1 (p.R132H) mutation in our analysis. Our findings not only provide potential biomarkers for earlier screening of extraneural metastasis, but could also suggest clues to understanding biological mechanisms underlying GBM metastasis, and for the development of therapeutic modalities.

Neuroendocrine Tumors of the Thyroid and Their Mimics.

This paper will review neuroendocrine lesions of the thyroid and the differential diagnosis with the most significant such tumor of the thyroid, that is, medullary thyroid carcinoma. A brief overview of the understanding of this tumor's identification as a lesion of C cells and its familial and syndromic associations will be presented. Then, a discussion of the various mimics of medullary carcinoma will be given with an approach to the types of tests that can be done to arrive at a correct diagnostic conclusion. This review will focus on practical "tips" for the practicing pathologist.

Noninvasive Follicular Tumor With Papillary-like Nuclear Features: A Practice Changer in Thyroid Pathology.

CONTEXT.­: This article presents a review of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), including its separation from follicular variant of papillary carcinoma of the thyroid, its evolution, and current definition and pathologic characteristics. OBJECTIVES.­: To emphasize the understanding of the concept of NIFTP as a neoplasm based on molecular analyses, its critical histopathologic features, the microscopic findings that exclude the diagnosis, and the importance of complete sectioning of the tumor to exclude neoplasms that should be diagnosed as carcinomas. Important distinctions are discussed including difficulties with literature that shows NIFTP with metastases, inadequacy of sectioning of the tumor, and lack of descriptive histology of the surrounding thyroid and possible other lesions. DATA SOURCES.­: Review of articles in the English literature on NIFTP, as well as comparative papers showing differences and distinctions between this entity and papillary carcinomas. CONCLUSIONS.­: This article concludes that with the current state of knowledge on NIFTP with studies from all over the world, this entity is a low-risk neoplasm that, when diagnosed using appropriate criteria, should not be associated with metastatic or recurrent disease, at least on intermediate length of follow-up. This review includes discussion of multifocal NIFTP, as well as the recently defined micro-NIFTP (1 cm or less), and describes features of the tumor that remain to be studied and correlated with outcome: oncocytic variants of NIFTP, percentage of allowable solid areas of growth in the lesions, and definitions of true neoplastic papillae and hyperplastic ones and how these should influence the diagnosis of NIFTP.

A case of tumor-to-tumor metastasis of cutaneous malignant melanoma.

We report a case of tumor-to-tumor metastasis of a cutaneous malignant melanoma to a synchronous thyroid Hurthle cell carcinoma. A 42-year-old male underwent a biopsy of right inguinal lymphadenopathy which showed metastatic melanoma. The primary lesion was identified on his right posterior leg, and staging workup discovered a synchronous left thyroid lobe nodule concerning for a follicular neoplasm. He underwent excision of the primary melanoma, right inguinal lymphadenectomy, and total thyroidectomy. The resected thyroid contained a 6.6-cm, well-encapsulated left-sided nodule, red-brown in color and homogenous in consistency, with areas of focal hemorrhage and no grossly identifiable calcification. Microscopically, large tumor cells with distinct cell borders were present, with deeply eosinophilic and granular cytoplasm, large nuclei with prominent nucleoli, and loss of polarity consistent with oncocytes. A microscopic single focus of vascular invasion was identified, and a diagnosis of angioinvasive Hurthle cell carcinoma was made. Within the Hurthle cell carcinoma, multiple deposits of metastatic melanoma were seen. These findings were indicative of tumor-to-tumor metastasis of the cutaneous melanoma to the angioinvasive Hurthle cell carcinoma. Our findings show the ability of melanoma to metastasize to a pre-existing neoplasm.

Giant Cell Carcinosarcoma of the Parotid Gland With a PLAG 1 Translocation in Association With a Pleomorphic Adenoma With HMGA2 Translocation.

OBJECTIVES: Carcinosarcomas of the salivary gland are rare neoplasms and have been described arising de novo or in association with pleomorphic adenoma (PA). PLAG1 and HMGA2 translocations are known to occur in PAs and carcinomas ex PA but are mutually exclusive. METHODS: We report a case of a carcinosarcoma in the parotid gland of a 77-year-old man with unusual anaplastic sarcomatoid giant cell morphology. RESULTS: Microscopically, a small separate PA was found adjacent to the carcinosarcoma. By conventional notion, the PA and carcinosarcoma would be considered related, as carcinosarcomas are well known to arise from PAs (carcinosarcoma ex PA). However, fluorescence in situ hybridization (FISH) assay demonstrated PLAG1 translocation in the carcinosarcoma and HMGA2 translocation in the separate PA. CONCLUSIONS: These findings support that the carcinosarcoma likely originated from another PA with a PLAG1 translocation or de novo but not from the coexisting PA harboring a different translocation. To our knowledge, the case is the first to demonstrate PLAG1 translocation by FISH in a sarcomatous component of any parotid gland tumor, which may help better classify these tumors. In addition, multiple PAs are commonly found in the salivary gland, and to our knowledge, our case is the first to demonstrate that the same parotid gland can host PAs and PA-related tumors with different translocations.

The significance of mucinous metaplasia in Warthin tumor: a frequent occurrence and potential pitfall.

Mucinous metaplasia in Warthin tumor (WT) is a recognized phenomenon. Nevertheless, its presence can create a diagnostic challenge in the distinction from the newly proposed variant of mucoepidermoid carcinoma (MEC), Warthin-like MEC. In this study, we evaluated the significance and diagnostic relevance of mucinous metaplasia in WTs. A total of 30 WTs diagnosed based on resection specimens formed the basis of this retrospective study. Mucicarmine staining was performed to identify mucinous metaplasia, and fluorescence in situ hybridization (FISH) analysis was used to detect MAML2 gene rearrangement. After review, one MAML2 rearranged case was reclassified as Warthin-like MEC as the classic bilayered epithelium in WT was not identified. The diagnosis of WT was confirmed in the remaining 29 cases. Mucinous metaplasia was encountered in 24 WTs (83%), with 14% (4/29) having an abundant amount. We found that mucinous metaplasia correlated with tumor size (p < 0.05). Age and sex distribution were similar in WT cases with or without mucinous metaplasia. In addition, neither the presence of squamous metaplasia nor the time interval between fine-needle aspiration and surgery was related to mucinous metaplasia (p > 0.05). The MAML2 FISH analyses performed in 18 WTs with variable amounts of mucinous metaplasia were negative for rearrangement. In conclusion, mucinous metaplasia is fairly common in WTs and shows a significant correlation with tumor size. Therefore, caution should be taken to avoid overinterpretation of WT with mucinous metaplasia as MEC in cases showing the classic bilayered oncocytic lining epithelium.

Practice Paradigms Before and After Introduction of the Diagnosis-Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features (NIFTP): an Institutional Experience.

The recently adopted terminology of "Noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP) reflects the indolent behavior of these tumors. In contrast to conventional papillary thyroid carcinomas, NIFTP can be managed conservatively. The purpose of this study was to investigate changes in surgical and pathologic practice patterns at our institution since the introduction of the NIFTP diagnosis in 2016. A retrospective analysis of all thyroid specimens received in our laboratory between January 2015 and April 2017 was performed. The final cohort consisted of 1508 thyroidectomy specimens from 1508 patients (1153 (76.5%) women and 355 (23.5%) men), of which 1011 (67%) were total thyroidectomies and 497 (33%) were partial thyroidectomies. There were 558 (69.2%) total thyroidectomies and 248 (30.8%) partial thyroidectomies performed prior to introduction of the NIFTP diagnosis and 453 (64.5%) and 249 (35.5%) total and partial thyroidectomies, respectively, after the change in nomenclature. Within a year following the initial use of this diagnosis, 67 NIFTP cases were identified (9.5% of all thyroidectomies), whereas compared with the year preceding it, malignant diagnoses decreased from 54.5 (439) to 44.6% (313), and the benign category remained unchanged from 44.5 (367) to 45.9% (322). For the entirely submitted 67 NIFTP cases, the mean number of blocks submitted was 14.7 (0.98 blocks/g); for malignant lesions 17.7 (0.92 blocks/g); and for benign lesions 16.6 (0.75 blocks/g). The results of our study suggest that NIFTP are encountered in almost 10% of thyroidectomies at our institution with expected shifts in cytology and surgical pathology diagnoses as a result of the change in nomenclature. During this time period, significant shifts towards less aggressive surgical management were not observed. All 67 NIFTP nodules were submitted entirely with no significant difference in the number of cassettes submitted for NIFTP nodules as compared with follicular variant papillary thyroid carcinoma (PTC), classic variant PTC, or follicular adenoma.