Genomic profile of columnar cell variant of papillary thyroid carcinoma.

BACKGROUND AND AIMS: Columnar cell variant (CCV) is a rare papillary thyroid carcinoma subtype. The majority of CCV occur in older patients and are large, invasive tumours that pursue an aggressive clinical course. Rare well-circumscribed CCV occur in younger female patients and are comparatively indolent. METHODS AND RESULTS: We retrospectively identified CCV with material available to perform targeted next-generation sequencing and correlated molecular results with clinicopathological features and outcome. Our cohort was comprised of nine CCV. Nearly all were aggressive tumours; however, one was predominantly well-circumscribed and arose in a thyroglossal duct cyst of a 26-year-old woman who had no evidence of disease at last follow-up. Seven (78%) cases demonstrated activating oncogenic driver alterations in BRAF, including BRAF V600E, an activating N486_P490del deletion, and BRAF-AGK fusions. Activating RAS mutations were seen in two (22%) cases. Additionally, three (33%) cases had TERT promoter mutations, four (44%) had loss of the tumour suppressor CDKN2A and one (11%) case had a loss of function TP53 mutation. Most cases (89%) also demonstrated copy number alterations, including recurrent gain of chromosome 1q (five cases) and losses of chromosome 9p (three cases) and 22q (four cases). The one case without secondary pathogenic mutations or copy number alterations was the tumour in the 26-year-old woman. CONCLUSIONS: We found that CCV is primarily a BRAF-driven tumour, with most also harbouring secondary oncogenic mutations and multiple chromosomal gains and losses. Moreover, our findings suggest that molecular analysis could potentially be used to help risk stratify CCV.

Histological features of BRAF V600E-mutant anaplastic thyroid carcinoma.

AIMS: Treatment with a BRAF inhibitor, alone or in combination with a MEK inhibitor, may be considered for BRAF-mutant anaplastic thyroid carcinoma (ATC). The purpose of this study was to characterise the histology of BRAF V600E-mutant ATC. METHODS AND RESULTS: We identified 28 ATC that were consecutively resected between 2003 and 2019. All tumour slides for each case were evaluated for the presence of a precursor tumour and for ATC morphology (sarcomatoid, pleomorphic giant cell, epithelioid or squamous). BRAF V600E mutation status was determined by BRAF V600E IHC or molecular analysis (OncoPanel NGS). Eighteen (64%) ATC had an associated well-differentiated precursor, including 10 (36%) with associated papillary thyroid carcinoma (PTC) and eight (29%) with associated follicular thyroid carcinoma (FTC) or Hürthle cell carcinoma (HCC). Most ATC (19 cases, 68%) demonstrated a mixed anaplastic morphology. Squamous morphology was present in four cases. Ten (36%) ATC had a BRAF V600E mutation. All ATC that had a PTC precursor had a BRAF V600E mutation (and all ATC with a BRAF V600E mutation had a PTC precursor), whereas no ATC with an FTC or HCC precursor had a BRAF V600E mutation. All four cases of ATC with a squamous morphology had a PTC precursor and a BRAF V600E mutation. CONCLUSION: In our cohort, the presence of a PTC precursor predicted the presence of the BRAF V600E mutation, whereas ATC with an FTC or HCC precursor lacked a BRAF V600E mutation. A squamous morphology was associated with the presence of a PTC precursor and a BRAF V600E mutation.

A potential diagnostic pitfall for hobnail variant of papillary thyroid carcinoma.

AIMS: Hobnail variant of papillary thyroid carcinoma (PTC) is an aggressive PTC subtype characterised by a hobnail cytomorphology. However, some classic PTC have a 'hobnail-like' cytomorphology associated with thick, hyalinised, variably oedematous fibrovascular cores that appears to be a form of ischaemic/degenerative atypia. METHODS AND RESULTS: We studied three cohorts to compare the histopathological characteristics and clinical outcome of 'hobnail-like' classic PTC and true hobnail variant of PTC: cohort 1, PTC consecutively resected between 2016 and 2017 (to assess frequency of 'hobnail-like' cytomorphology); cohort 2, 20 'hobnail-like' classic PTC resected between 2005 and 2007 (to assess clinical outcome); and cohort 3, seven true hobnail variant of PTC. A 'hobnail-like' cytomorphology was identified in 16% of consecutively resected PTC. Compared with true hobnail variant, 'hobnail-like' classic PTC occurred in younger patients (mean age 40 years versus 68 years, P < 0.001), were smaller tumours (mean tumour size 2.1 cm versus 4.4 cm, P < 0.001), had a lower rate of gross extrathyroidal extension (0% versus 71%, P < 0.001), had a lower proliferative rate (≥3 mitoses per 10 high-power fields seen in 0% versus 71%, P < 0.001; Ki67 index ≥5% in 0% versus 86%, P < 0.001), a lower rate of secondary pathogenic mutations (for cases with molecular data, 0% versus 100%, P = 0.0061) and improved survival (for cases with sufficient clinical outcome data, 10-year disease-free survival of 93% versus 0%, P = 0.0016). CONCLUSION: Classic PTC can show ischaemic/degenerative atypia that mimics the hobnail cytomorphology of true hobnail variant; however, these tumours lack aggressive histopathological features and pursue an indolent clinical course.

Assessment of a Personal Interactive Carbon Monoxide Breath Sensor in People Who Smoke Cigarettes: Single-Arm Cohort Study.

BACKGROUND: Tobacco use is the leading cause of preventable morbidity and mortality. Existing evidence-based treatments are underutilized and have seen little recent innovation. The success of personal biofeedback interventions in other disease states portends a similar opportunity in smoking cessation. The Pivot Breath Sensor is a personal interactive FDA-cleared (over-the-counter) device that measures carbon monoxide (CO) in exhaled breath, enabling users to link their smoking behavior and CO values, and track their progress in reducing or quitting smoking. OBJECTIVE: The objective of this study is to assess the Pivot Breath Sensor in people who smoke cigarettes, evaluating changes in attitudes toward quitting smoking, changes in smoking behavior, and use experience. METHODS: US adults (18-80 years of age, ≥10 cigarettes per day [CPD]) were recruited online for this remote 12-week study. Participants completed a screening call, informed consent, and baseline questionnaire, and then were mailed their sensor. Participants were asked to submit 4 or more breath samples per day and complete questionnaires at 1-4, 8, and 12 weeks. Outcomes included attitudes toward quitting smoking (Stage of Change, success to quit, and perceived difficulty of quitting), smoking behavior (quit attempts, CPD reduction, and 7-, 30-day point prevalence abstinence [PPA]), and use experience (impact and learning). RESULTS: Participants comprised 234 smokers, mean age 39.9 (SD 11.3) years, 52.6% (123/234) female, mean CPD 20.3 (SD 8.0). The 4- and 12-week questionnaires were completed by 92.3% (216/234) and 91.9% (215/234) of participants, respectively. Concerning attitude outcomes, at baseline, 15.4% (36/234) were seriously thinking of quitting in the next 30 days, increasing to 38.9% (84/216) at 4 weeks and 47.9% (103/215) at 12 weeks (both P<.001). At 12 weeks, motivation to quit was increased in 39.1% (84/215), unchanged in 54.9% (118/215), and decreased in 6.0% (13/215; P<.001). Additional attitudes toward quitting improved from baseline to 12 weeks: success to quit 3.3 versus 5.0 (P<.001) and difficulty of quitting 2.8 versus 4.3 (P<.001). Regarding smoking behavior, at 4 weeks, 28.2% (66/234) had made 1 or more quit attempts (≥1 day of abstinence), increasing to 48.3% (113/234) at 12 weeks. At 4 weeks, 23.1% (54/234) had reduced CPD by 50% or more, increasing to 38.5% (90/234) at 12 weeks. At 12 weeks, CPD decreased by 41.1% from baseline (P<.001), and 7- and 30-day PPA were 12.0% (28/234) and 6.0% (14/234), respectively. Concerning use experience, 75.3% (171/227) reported the sensor increased their motivation to quit. More than 90% (>196/214) indicated the sensor taught them about their CO levels and smoking behavior, and 73.1% (166/227) reported that seeing their CO values made them want to quit smoking. CONCLUSIONS: Use of the Pivot Breath Sensor resulted in a significant increase in motivation to quit, a reduction in CPD, and favorable quit attempt rates. These outcomes confer increased likelihood of quitting smoking. Accordingly, the results support a role for biofeedback via personal CO breath sampling in smoking cessation. TRIAL REGISTRATION: ClinicalTrials.gov NCT04133064; https://clinicaltrials.gov/ct2/show/NCT04133064.

Proceedings of the 2024 North American Society of Head and Neck Pathology Companion Meeting, Baltimore, MD, March 24, 2024: Navigating Ancillary Studies in Basaloid/Blue Salivary Tumors.

BACKGROUND: Basaloid salivary tumors can demonstrate significant morphologic overlap and be challenging to diagnose. METHODS: A review of select ancillary studies in basaloid salivary tumors was performed. RESULTS: A number of immunohistochemical stains, including PLAG1, HMGA2, ß-catenin, MYB, and RAS Q61R, have been more recently incorporated into the diagnostic workup of basaloid salivary tumors. CONCLUSIONS: Although reported variability in their performance has perhaps limited their widespread adoption, these immunohistochemical studies can nevertheless be useful in supporting pathologic diagnoses, particularly when considered in more specific differentials or when used as a panel with other markers.

Nivolumab for Patients With High-Risk Oral Leukoplakia: A Nonrandomized Controlled Trial.

Importance: Proliferative verrucous leukoplakia (PVL) is an aggressive oral precancerous disease characterized by a high risk of transformation to invasive oral squamous cell carcinoma (OSCC), and no therapies have been shown to affect its natural history. A recent study of the PVL immune landscape revealed a cytotoxic T-cell-rich microenvironment, providing strong rationale to investigate immune checkpoint therapy. Objective: To determine the safety and clinical activity of anti-programmed cell death 1 protein (PD-1) therapy to treat high-risk PVL. Design, Setting, and Participants: This nonrandomized, open-label, phase 2 clinical trial was conducted from January 2019 to December 2021 at a single academic medical center; median (range) follow-up was 21.1 (5.4-43.6) months. Participants were a population-based sample of patients with PVL (multifocal, contiguous, or a single lesion ≥4 cm with any degree of dysplasia). Intervention: Patients underwent pretreatment biopsy (1-3 sites) and then received 4 doses of nivolumab (480 mg intravenously) every 28 days, followed by rebiopsy and intraoral photographs at each visit. Main Outcomes and Measures: The primary end point was the change in composite score (size and degree of dysplasia) from before to after treatment (major response [MR]: >80% decrease in score; partial response: 40%-80% decrease). Secondary analyses included immune-related adverse events, cancer-free survival (CFS), PD-1 ligand 1 (PD-L1) expression, 9p21.3 deletion, and other exploratory immunologic and genomic associations of response. Results: A total of 33 patients were enrolled (median [range] age, 63 [32-80] years; 18 [55%] were female), including 8 (24%) with previously resected early-stage OSCC. Twelve patients (36%) (95% CI, 20.4%-54.8%) had a response by composite score (3 MRs [9%]), 4 had progressive disease (>10% composite score increase, or cancer). Nine patients (27%) developed OSCC during the trial, with a 2-year CFS of 73% (95% CI, 53%-86%). Two patients (6%) discontinued because of toxic effects; 7 (21%) experienced grade 3 to 4 immune-related adverse events. PD-L1 combined positive scores were not associated with response or CFS. Of 20 whole-exome sequenced patients, all 6 patients who had progression to OSCC after nivolumab treatment exhibited 9p21.3 somatic copy-number loss on pretreatment biopsy, while only 4 of the 14 patients (29%) who did not develop OSCC had 9p21.3 loss. Conclusions and Relevance: This immune checkpoint therapy precancer nonrandomized clinical trial met its prespecified response end point, suggesting potential clinical activity for nivolumab in high-risk PVL. Findings identified immunogenomic associations to inform future trials in this precancerous disease with unmet medical need that has been difficult to study. Trial Registration: ClinicalTrials.gov Identifier: NCT03692325.

Challenges in Encapsulated Follicular-Patterned Tumors: How Much Is Enough? Evaluation of Nuclear Atypia, Architecture, and Invasion.

Thyroid pathology is notoriously fraught with high interobserver variability, and follicular-patterned tumors are among some of the most challenging to assess accurately and reproducibly. Given that encapsulated or well-circumscribed follicular-patterned tumors often have similar molecular profiles, that is, frequent RAS or RAS-like alterations, the diagnosis usually relies on histopathologic examination alone. Unfortunately, many of the features that are used for diagnosis and prognosis of these tumors have long been controversial and frequently debated topics, both due to their subjectivity and their evolving (or not yet resolved) definitions. In more recent years, the introduction of noninvasive follicular thyroid neoplasm with papillary-like nuclear features has added further complexity to this discussion. In particular, the criteria and significance of nuclear features of papillary thyroid carcinoma, architectural patterns, and invasive growth still pose significant diagnostic challenges and confusion. This review explores some of the challenges in evaluating encapsulated follicular-patterned tumors, focusing on those histologic elements.

Degenerative atypia in benign thyroid nodules: a potential diagnostic pitfall on fine-needle aspiration.

INTRODUCTION: Benign (B) follicular lesions of the thyroid are among the most encountered specimens on fine needle aspiration (FNA). Although FNA and The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) remain highly accurate, minimally invasive and robust tools in triaging thyroid nodules, false positive (FP) diagnoses may still occur. Endocrine-type degenerative atypia can cause diagnoses of suspicious for malignancy (SFM) or malignant (M), resulting in overtreatment and exposure to undue surgical risk in patients. MATERIALS AND METHODS: We performed a multi-institutional retrospective clinicopathologic correlation of benign thyroid nodules with degenerative atypia on FNA. Review of cytologic material was conducted to identify potential cytomorphologic features which may have prompted these diagnoses. RESULTS: Among 342 patients with benign thyroid nodules harboring degenerative atypia, 123 had available preceding FNA cytopathology. TBSRTC nondiagnostic, B, atypia of undetermined significance, follicular neoplasm, SFM, and M, comprised 3.3%, 49.6%, 30.1%, 13.0%, 2.4%, and 1.6% of cases. Among patients with FP diagnoses (SFM and M), 100% underwent total thyroidectomy, and 40.0% underwent additional neck lymph node dissections. Among remaining patients, 61.0%, 39.0%, and 0% underwent lobectomy, thyroidectomy, and lymph node dissection. The number of patients who underwent total thyroidectomy was significantly different (P = 0.03) between those with FP nodules and those without. CONCLUSIONS: We demonstrate that 4.1% of nodules harboring endocrine-type degenerative atypia may be given FP diagnoses on initial FNA. Such atypia may be indistinguishable from that of Graves' Disease, dyshormonogenic goiter, and radiation therapy. FP diagnoses of degenerative atypia can expose patients to undue surgical procedures and risks.

The new endocrine WHO classification: What does this mean for thyroid cytology?

The new World Health Organization classification of endocrine tumors will include many updates on thyroid pathology. This summary highlights the changes that are most relevant for cytopathologists.

Grading of Medullary Thyroid Carcinoma: an Interobserver Reproducibility Study.

Grade, based on proliferative activity and tumor necrosis, has recently been shown to be prognostic in medullary thyroid carcinoma (MTC) in multivariate analysis. The aim of this study was to evaluate the interobserver reproducibility of assessed grade in MTC. Three groups (each group included one resident/fellow and one attending pathologist) independently evaluated a cohort of 44 sporadic MTC. For each case, all available tumor slides were reviewed, and mitotic count and the presence of tumor necrosis were recorded. Ki-67 was performed, and the Ki-67 proliferative index was determined in the area of highest proliferative activity. Tumors were graded according to the recently published International Medullary Thyroid Carcinoma Grading System (IMTCGS). Kappa statistics were calculated for each individual criterion (mitotic count, Ki-67 proliferative index, and necrosis) and for assigned IMTCGS grade. For our cohort of 44 MTCs, the kappa statistic for mitotic count, Ki-67 proliferative index, and necrosis was 0.68, 0.86, and 0.89, respectively. The kappa statistic for assigned IMTCGS grade was 0.87. Our findings indicate that there was a strong level of agreement for assessment of grade in our cohort of MTC, indicating that grade as assessed by the IMTCGS is not only prognostic but also reproducible.

NR4A3 Immunohistochemistry Reliably Discriminates Acinic Cell Carcinoma from Mimics.

Acinic cell carcinoma (AciCC) harbors a recurrent t(4;9)(q13;q31) translocation, which leads to upregulation of Nuclear Receptor Subfamily 4 Group A Member 3 (NR4A3). Previous work on tissue microarrays suggests that NR4A3 immunohistochemistry (IHC) may be useful in the diagnosis of AciCC. Thus far, only a single study has evaluated the utility of NR4A3 immunohistochemistry (IHC) in the diagnosis of AciCC, using a tissue microarray to assess most non-AciCC tumor types. Herein we evaluate the diagnostic performance of NR4A3 IHC for AciCC in a large cohort of 157 salivary gland tumors, using whole tissue sections. The cohort consisted of 37 AciCC (6 of them (16%) with high grade transformation), 30 secretory carcinomas (SC), and 90 additional salivary gland tumors, including mucoepidermoid carcinomas (MEC), polymorphous adenocarcinomas (PAC), pleomorphic adenomas (PA), salivary duct carcinomas (SDC), and adenoid cystic carcinomas (AdCC). NR4A3 nuclear staining by IHC was considered positive if present in more than 5% of tumor cells. Overall, 92% of AciCC (34/37) expressed NR4A3 by IHC, with strong (89%) or moderate (3%) nuclear staining, yielding a sensitivity of 92%. IHC detected NR4A3 expression in all cases of recurrent/metastatic AciCC and tumors with high grade transformation. Importantly, all SC were negative for NR4A3 IHC, with no staining in 28/30 cases and weak focal staining, in < 5% of cells, in 2/30 (7%). Similarly, all MEC (20/20), SDC (20/20) and AdCC (10/10) were negative for NR4A3 by IHC, as were most PA (18/20; 15%) and PAC (18/20; 5%). Two PA and two PAC showed multifocal expression of NR4A3 in more than 5% of cells, of weak intensity in 3 cases and moderate in 1 PAC, yielding an overall specificity of 97% for NR4A3 IHC for the diagnosis of AciCC. In conclusion, NR4A3 is a highly sensitive and specific immunohistochemical marker for AciCC; moderate to strong and/or diffuse NR4A3 expression is a consistent and diagnostic feature of AciCC.

Hürthle cell lesions of the thyroid: Progress made and challenges remaining.

Hürthle cell-predominant thyroid fine needle aspirations (FNA) are encountered frequently in routine practice, yet they are often challenging to diagnose accurately and are associated with significant interobserver variability. This is largely due to the ubiquity of Hürthle cells in thyroid pathology, ranging from nonneoplastic conditions to aggressive malignancies. Although limitations in cytomorphologic diagnoses likely will remain for the foreseeable future, our knowledge of the molecular pathogenesis of Hürthle cell neoplasia and application of molecular testing to cytologic material have increased dramatically within the past decade. This review provides context behind the challenges in diagnosis of Hürthle cell lesions and summarizes the more recent advances in diagnostic tools.

Papillary Thyroid Carcinoma with High-Grade Features Versus Poorly Differentiated Thyroid Carcinoma: An Analysis of Clinicopathologic and Molecular Features and Outcome.

Background: Similar to poorly differentiated thyroid carcinoma (PDTC), papillary thyroid carcinoma with high-grade features (PTC HGF) demonstrates increased mitotic activity and/or necrosis; however, PTC HGF is excluded from the World Health Organization (WHO) definition of PDTC based on maintained nuclear features of PTC. Methods: Consecutive tumors that met criteria for PTC HGF, defined as tumors with maintained nuclear features of PTC and mitoses numbering 5 or more per 10 contiguous high-power fields and/or tumor necrosis, and PDTC (defined as per the WHO criteria) were identified. Clinicopathologic characteristics, follow-up data, and targeted next-generation sequencing results were compared between groups. Results: There were 15 PTC HGF and 47 PDTC. PTC HGF was associated with a higher rate of pT4 disease (53% vs. 13%, p = 0.0027) and lymph node metastases (73% vs. 38%, p = 0.049). The disease-specific survival was worse for patients with PTC HGF compared with those with PDTC using Kaplan-Meier estimation (p < 0.001) and was worse in subgroup analysis evaluating patients with widely invasive PDTC (i.e., those with a similar rate of pT4 disease) and PTC HGF (p = 0.040). PTC HGF had a higher BRAFV600E mutation rate (42% vs. 3%; p = 0.003), a trend toward more gene fusions (25% vs. 3%; p = 0.052), and a higher rate of relative gain of 1q (67% vs. 15%; p = 0.002) than PDTC. Conclusions: Our results demonstrate that PTC HGF are important to recognize based on their aggressive behavior. The molecular differences between PTC HGF and PDTC suggest that PTC HGF should be considered a distinct group from PDTC.

Histopathologic Features and Clinical Outcome of Anaplastic Thyroid Carcinoma with a Minor Anaplastic Component.

Although prior studies have reported that patients with anaplastic thyroid carcinoma (ATC) with a focal anaplastic component may have a prolonged survival compared to other ATC patients, the outcome data are limited. We evaluated a cohort of ATC resected between 2003 and 2018. Tumor slides were reviewed to confirm the diagnosis and to identify cases with a minor ATC component (defined as comprising < 10% of the tumor). We evaluated the clinical outcome of these patients compared to that of all other cohort patients (characterized as having conventional ATC). Our cohort was composed of 24 cases of ATC that underwent resection, including 8 (33%) with a minor ATC component. Tumors with a minor ATC component were predominantly associated with papillary thyroid carcinoma. For patients with tumors with a minor ATC component, the 1-year and 2-year survival rates and median survival for patients who died of disease were 88%, 43%, and 17 months (range 6-73 months), respectively. In comparison, for patients with conventional ATC, the 1-year and 2-year survival rates and median survival for patients who died of disease were 56%, 44%, and 7 months (range 2-26 months), respectively. There was no difference in 1- and 2-year survival or overall survival by Kaplan-Meier analysis for patients with tumors with a minor ATC component and those with conventional ATC. In conclusion, the difference in overall survival between ATC groups in our cohort was not significant; however, this could be due to the small cohort size or due to characteristics of our group with a minor ATC component; that is, no tumors in this group were limited to the thyroid (stage IVA), resectability with negative margins was infrequent, and 38% of this group had distant metastases at diagnosis (stage IVC).

Malignancy risk for solitary and multiple nodules in Hürthle cell-predominant thyroid fine-needle aspirations: A multi-institutional study.

BACKGROUND: Hürthle cell metaplasia is common in hyperplastic nodules, particularly within the setting of lymphocytic thyroiditis (LT). The Bethesda System for Reporting Thyroid Cytopathology indicates that it is acceptable to classify Hürthle cell-predominant fine-needle aspiration (HC FNA) specimens as atypia of undetermined significance (AUS) rather than suspicious for a Hürthle cell neoplasm (HUR) within the setting of multiple nodules or known LT. The goal of the current study was to address whether this approach is justified. METHODS: HC FNA specimens were identified and correlated with ultrasound and surgical pathology reports if available. Multinodularity was determined based on findings on macroscopic examination if imaging results were unavailable. RESULTS: A total of 698 HC FNA specimens were identified, including 576 resected nodules, 455 of which (79%) were benign. The overall risk of malignancy for HUR was 27%, whereas the risk of malignancy for AUS was 10%. The mean size of the benign nodules was 2.1 cm on surgical resection specimens, with multiple nodules noted in 293 cases (64%) and histologic LT noted in 116 cases (25%). The mean size of the malignant nodules was 2.8 cm, with multiple nodules and histologic LT noted in 74 cases (61%) and 22 cases (18%), respectively. The malignancy rate did not differ between solitary or multiple nodules (P = .52) or in the presence or absence of LT (P = .12). However, size did significantly differ between malignant and benign nodules (P < 0.01). CONCLUSIONS: The malignancy rate did not differ significantly in the presence of multiple nodules or LT, although the latter demonstrated a statistical trend. A diagnosis of AUS over HUR based solely on the presence of multinodularity is not warranted.

Thyroid Tumors You Don't Want to Miss.

This article examines more uncommon thyroid entities, including anaplastic thyroid carcinoma, poorly differentiated thyroid carcinoma, rare papillary thyroid carcinoma variants, medullary thyroid carcinoma, non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), and multiple adenomatous nodules in the setting of Cowden syndrome. These entities were chosen based on their clinical significance and because they can be diagnostically challenging due to their morphologic diversity and overlap with other thyroid tumors. This article addresses the diagnostic features of each entity, focusing on how to avoid potential pitfalls and mimics while also highlighting the clinical implications of each diagnosis.

Heterogeneity of p16 immunohistochemistry and increased sensitivity of RNA in situ hybridization in cytology specimens of HPV-related head and neck squamous cell carcinoma.

BACKGROUND: Many patients with human papillomavirus (HPV)-related head and neck squamous cell carcinoma (HPV-HNSCC) initially present with cervical lymph node metastases. Although p16 immunohistochemistry (IHC) is the most commonly used surrogate marker for HPV, however criteria in cytologic material are not well established. The objective of this study was to better characterize p16 IHC in cell blocks of metastatic HPV-HNSCC, and to evaluate the performance of HPV RNA in situ hybridization (RNA ISH). METHODS: p16 IHC was performed on cell blocks from 97 metastatic HPV-HNSCC fine-needle aspiration specimens with HPV status confirmed by DNA or RNA ISH or polymerase chain reaction (PCR). Tumor cellularity (<100 cells, 100-500 cells, and >500 cells) and quality (presence of cell clusters, necrosis) were recorded. p16 staining intensity and extent (1%-9%, 10%-69%, and ≥70%) were scored. In addition, RNA ISH was performed on 38 PCR-positive cases. RESULTS: p16 IHC was positive in 90 of 97 cases (93%), demonstrating variable patterns. p16 staining was found to be moderate to strong in 69 cases, with 37 cases (38%) demonstrating positivity in ≥70% of tumor cells. Weak staining occurred in 21 cases (22%) and 7 cases (7%) were negative. Of the 60 cases with weak and/or absent expression or staining in <70% of cells, 30 cases (50%) had <100 tumor cells, 12 (20%) lacked cell clusters, and 19 cases (32%) had extensive necrosis. RNA ISH was positive in 37 of 38 cases (97%) that were HPV positive by PCR. CONCLUSIONS: p16 is heterogeneous in cell blocks of metastatic HPV-HNSCC, suggesting that any p16 positivity should prompt confirmatory HPV studies. RNA ISH appears to demonstrate high sensitivity, and laboratories even may consider using RNA ISH as a first-line HPV test in cytologic specimens.

Tall Cell Variant of Papillary Thyroid Carcinoma: Impact of Change in WHO Definition and Molecular Analysis.

The morphologic criteria for tall cell variant (TCV) of papillary thyroid carcinoma (PTC) were modified in the 2017 WHO Classification of Tumors of Endocrine Organs, with a decrease in the requirements for both the height of cells and in the percentage of tumor demonstrating a tall cell morphology. The aim of this study was to determine if the change in criteria would result in a significant increase in the percentage of tumors that meet criteria for TCV. In addition, we evaluated the correlation between morphology, molecular alterations, and clinical behavior of TCV. We studied three cohorts to evaluate the above stated questions. The first cohort was comprised of 97 PTC consecutively resected over a 12-month period that were originally diagnosed as classic PTC, PTC with tall cell features, or TCV. Tumor slides of each case were reviewed to determine the percentage of the tall cell component (< 30%, 30-49%, and > 50%) and the height of the cells in this component. This cohort was evaluated to determine if the change in WHO criteria would result in a significant increase in the percentage of tumors that meet criteria for TCV. Our second cohort consisted of nine consecutively resected PTC with a tall cell component > 30% (with tall cells defined as at least 2-3× as tall as wide) that had molecular characterization through a targeted, next-generation sequencing (NGS) assay. The molecular characteristics were correlated with the percentage of the tall cell component. Finally, a third cohort comprised of seven clinically aggressive TCV (defined as those with T4 disease, disease recurrence, or subsequent tumor dedifferentiation) was evaluated to determine histologic and molecular characteristics. In cohort 1, the number of cases classified as TCV increased significantly with the change in definition of TCV: 8 (8%) cases met the previous criteria for TCV (cells 3× as tall as wide in > 50% of the tumor), whereas 24 (25%) cases met the new 2017 WHO criteria (cells 2-3× as tall as wide in > 30% of the tumor) (p = 0.0020). Molecular analysis of cohort 2 revealed that all 9 cases harbored a BRAF V600E mutation. Pathogenic secondary mutations were absent in cases with < 50% tall cells, but they were detected in 2 (33%) of 6 cases with > 50% tall cells (2 cases with TERT promoter mutations, including 1 that also had an AKT2 mutation). Histologic and molecular analysis of the clinically aggressive cohort (cohort 3), revealed that all cases had > 50% tall cells and 3 (43%) had secondary oncogenic mutations (all TERT promoter mutations). We found that the modified morphologic criteria put forth in the 2017 WHO tripled the number of cases that would be classified as TCV. Moreover, clinically aggressive tumors and those harboring secondary oncogenic mutations all had a tall cell component > 50%. Additional large multi-institutional studies incorporating clinical outcome and molecular data would be valuable to determine the best histologic definition of TCV.

Prognostic Significance of Extent of Invasion in Poorly Differentiated Thyroid Carcinoma.

Background: The 2017 World Health Organization (WHO) Classification of Tumors of Endocrine Organs defines poorly differentiated thyroid carcinoma (PDTC) as a tumor with conventional criteria of malignancy (capsular penetration or vascular invasion) with solid, insular, or trabecular growth, a lack of nuclear features of papillary thyroid carcinoma, and increased mitotic activity, tumor necrosis, or convoluted nuclei. The extent of invasion has been shown to be prognostic in follicular thyroid carcinoma and Hürthle cell carcinoma. Our aim was to evaluate how extent of invasion impacts clinical outcome for PDTC. Methods: We retrospectively identified 47 consecutively diagnosed cases of PDTC that were resected between 2005 and 2018. All cases were reviewed to confirm that the tumors met the 2017 Endocrine WHO criteria of PDTC. In addition, tumors were categorized as follows: encapsulated with capsular penetration only, encapsulated with focal vascular invasion (fewer than four foci), encapsulated with extensive vascular invasion (four or more foci), or widely invasive. Histopathologic characteristics and clinical outcome data were recorded. Results: A total of 47 cases of PDTC, including 15 oncocytic tumors, were identified from 28 (60%) women and 19 (40%) men (mean age of 57 years at diagnosis). The mean tumor size was 4.3 cm. Mitoses numbered 8 per 10 high-power fields (HPF) on average (range: 1-34), and necrosis was present in 21 (45%) cases. Eight (17%) cases were encapsulated with capsular penetration only, 5 (11%) were encapsulated with focal vascular invasion, 18 (38%) were encapsulated with extensive vascular invasion, and 16 (34%) were widely invasive. Of the 42 (89%) patients with follow-up data, 7 (17%) died of disease (with a mean survival time of 6.4 years), 11 (26%) have distant metastatic disease, and 24 (57%) have no evidence of disease (mean follow-up 5.6 years). Eight (19%) patients presented with M1 disease at diagnosis. The 5-year disease-free survival (DFS) for patients with M0 disease at diagnosis was 100% for patients with tumors with capsular invasion only or focal vascular invasion (n = 7), 73% for patients with encapsulated tumors with extensive vascular invasion (n = 11), and 17% for patients with widely invasive PDTCs (n = 6). DFS estimates by Kaplan-Meier analysis were significantly different between these groups (p = 0.0016). Conclusions: Extent of invasion appears to be an important parameter that affects clinical outcome for patients with PDTC. In our cohort, patients with encapsulated PDTC with capsular invasion only or focal vascular invasion had an excellent outcome.

Clinicopathologic Features of Mismatch Repair-Deficient Anaplastic Thyroid Carcinomas.

Background: Prior studies have reported mutations in mismatch repair (MMR) genes in a small subset of anaplastic thyroid carcinomas (ATC). The aim of this study was to identify MMR-protein-deficient (MMR-D) ATC and investigate their histopathologic features and clinical outcome. Methods: A cohort of 28 ATC diagnosed between 2003 and 2017 with tissue blocks available were evaluated. Immunohistochemistry for MMR proteins was performed to identify MMR-D tumors. Clinicopathologic features, molecular findings (determined by a targeted next-generation sequencing assay), and clinical outcome data for MMR-D tumors were recorded and compared to that of MMR-protein-intact (MMR-I) tumors. Results: There were four (14%) MMR-D ATC, all of which showed complete loss of MSH2 and MSH6 with intact expression of MLH1 and PMS2. Three of these tumors had MSH2 mutations and a hypermutated phenotype by next-generation sequencing. All four patients (two male; Mage at diagnosis = 64 years) presented with stage IVB disease (i.e., gross extrathyroidal extension or a lymph node metastasis at presentation). There were no differences in tumor size or rates of gross extrathyroidal extension, lymph node metastases, or positive resection margins between MMR-D and MMR-I ATC. Patients with MMR-D tumors were less likely to have distant metastatic disease at presentation (p = 0.035), although half did eventually develop distant metastases. MMR-D tumors were not histologically distinct. All four patients with MMR-D tumors lived for more than one year. One patient died of disease at 15 months, while the remaining three were alive at last follow-up, with survival of 19, 38, and 48 months. Patients with MMR-D ATC had significantly better survival compared to those with MMR-I tumors (p = 0.033), which was maintained when considering only patients with stage IVB disease at presentation (p = 0.030). Conclusion: MMR-D tumors comprised 14% of this ATC cohort. Although the findings must be interpreted with caution given the small number of MMR-D ATC in the cohort, the results suggest that MMR status may be prognostically significant in ATC.