Nonoperative, Active Surveillance of Larger Malignant and Suspicious Thyroid Nodules.

CONTEXT: Active surveillance for papillary thyroid cancer (PTC) meeting criteria for surgical resection is uncommon. Which patients may prove reasonable candidates for this approach is not well defined. OBJECTIVE: This work aimed to examine the feasibility and safety of active surveillance for patients with known or suspected intrathyroidal PTC up to 4 cm in diameter. METHODS: A retrospective review was conducted of all consecutive patients who underwent nonoperative active surveillance of suspicious or malignant thyroid nodules over a 20-year period from 2001 to 2021. We included patients with an initial ultrasound-fine-needle aspiration confirming either (a) Bethesda 5 or 6 cytology or (b) a "suspicious" Afirma molecular test. The primary outcomes and measures included the rate of adverse oncologic outcomes (mortality and recurrence), as well as the cumulative incidence of size/volume growth. RESULTS: Sixty-nine patients were followed with active surveillance for 1 year or longer (average 55 months), with 26 patients (38%) having nodules 2 cm or larger. No patients were found to develop new-incident occurrence of lymph node or distant metastasis. One patient, however, demonstrated concern for progression to a dedifferentiated cancer on repeat core biopsy 17 years after initial start of nonoperative selection. A total of 21% of patients had an increase in maximum diameter more than 3 mm, while volume increase of 50% or greater was noted in 25% of patients. Thirteen patients ultimately underwent delayed (rescue) surgery, and no disease recurrence was noted after such treatment. Age and initial nodule size were not predictors of nodule growth. CONCLUSION: These data expand consideration of active surveillance of PTC in select patients with intrathyroidal suspected malignancy greater than 1 cm in diameter. Rescue surgery, if required at a later time point, appears effective.

Additional Oncogenic Alterations in RAS-Driven Differentiated Thyroid Cancers Associate with Worse Clinicopathologic Outcomes.

PURPOSE: RAS mutations occur across the spectrum of thyroid neoplasms, and more tools are needed for better prognostication. The objective of this study was to evaluate how additional genetic events affecting key genes modify prognosis in patients with RAS-mutant thyroid cancers, and specifically differentiated thyroid cancers (DTC). EXPERIMENTAL DESIGN: We performed a clinical-genomic analysis of consecutive patients with DTC, poorly differentiated (PDTC), or anaplastic thyroid cancer (ATC) between January 2014 and December 2021, in whom a custom-targeted next-generation sequencing assay was performed. Patients harboring RAS mutations were included, and we compared their clinical features and outcomes based upon the presence of additional oncogenic alterations. RESULTS: Seventy-eight patients were identified, with 22% (17/78) harboring a driver RAS mutation plus an additional oncogenic alteration. All six (100%) ATCs had an additional mutation. Compared with DTCs harboring a solitary RAS mutation, patients with DTC with RAS and additional mutation(s) were more likely to be classified as American Thyroid Association high-risk of recurrence (77% vs. 12%; P < 0.001) and to have larger primary tumors (4.7 vs. 2.5 cm; P = 0.002) and advanced stage (III or IV) at presentation (67% vs. 3%; P < 0.001). Importantly, over an average 65-month follow-up, DTC-specific-mortality was more than 10-fold higher (20% vs. 1.8%; P = 0.011) when additional mutations were identified. CONCLUSIONS: Identification of key additional mutations in patients with RAS-mutant thyroid cancers confers a more aggressive phenotype, increases mortality risk in DTC, and can explain the diversity of RAS-mutated thyroid neoplasia. These data support genomic profiling of DTCs to inform prognosis and clinical decision-making.

Papillary Thyroid Carcinomas with Tall Cell Features: An Intermediate Entity Between Classic and Tall Cell Subtypes.

Background: While the diagnosis of papillary thyroid carcinomas (PTCs) with tall cell features (PTCtcf) is often made for carcinomas with histological features intermediate between classic and tall cell subtypes of PTC (tcPTC), its comparative signature to that of either tcPTC or classic PTC is less clear. The objective of this study was to perform an integrative clinicopathologic and genomic analysis elucidating the spectrum of tcPTC, PTCtcf, and classic PTC. Methods: We analyzed all consecutive patients with tcPTC and PTCtcf evaluated at a tertiary academic referral center between 2005 and 2020, as well as a comparative cohort of classic PTC, in a retrospective observational cohort analysis. Clinicopathologic data were compared among the three groups, including progression-free survival (PFS), recurrent/persistent disease, and a negative composite outcome of death, progression, or need for advanced therapy. To specifically understand differences between tcPTC and PTCtcf, targeted next-generation sequencing was performed in a subset of these cohorts. Results: A total of 292 patients were analyzed (81 tcPTC, 65 PTCtcf, 146 classic PTC). Thirteen percent of tcPTC versus 8% of PTCtcf versus 1% of classic PTC had the advanced American Joint Committee on Cancer stage (p = 0.002). Similarly, macroscopic extrathyroidal extension was observed in 38% of tcPTC, 14% of PTCtcf, and 12% of classic PTC (p < 0.001). The 5-year PFS was 76.5%, 81.5%, and 88.3% for tcPTC, PTCtcf, and classic PTC, respectively, while the rates of the negative composite outcome 40.2% for tcPTC, 20.7% for PTCtcf, and 11.2% for classic PTC (p < 0.001). In a multivariable Cox regression analysis, the negative composite outcome was independently associated with tcPTC (HR 4.3 [confidence interval 1.1-16.1], p = 0.03). tcPTC demonstrated substantially more hotspot TERT promoter mutations than PTCtcf (44% vs. 6%, p = 0.012). Conclusions: Our study demonstrates a continuum of disease-specific risk of PTC, pointing at PTCtcf as an intermediate entity between tcPTC and classic PTC. These data provide a more refined understanding of risk at time of presentation, while better elucidating the diversity of genomic drivers.

Identifying and Predicting Diverse Patterns of Benign Nodule Growth.

CONTEXT: The natural history of benign thyroid nodules is typically characterized by slow growth and minimal risk of malignant transformation. Available data have, to date, been unable to elucidate the diversity of benign nodule growth patterns over time nor predictive of which patients follow which pattern. OBJECTIVE: We aimed to better define the diverse patterns of benign nodule behavior and their predictors. METHODS: We prospectively studied 389 consecutive patients with solitary, solid, cytologically benign thyroid nodules ≥1 cm and follow-up ultrasound for at least 4 years. Demographic, sonographic, biochemical data were collected at initial evaluation, and subsequent growth patterns were identified over the follow-up. Predictors of growth at initial evaluation and 3 years of follow-up were defined. RESULTS: The mean (±SD) follow-up was 7.7 (±2.7) years. Three distinct growth patterns were identified: A) stagnant nodules with average growth rate < 0.2 mm/year; B) slow-growing nodules with a rate 0.2 to 1.0 mm/year; and C) fast-growing nodules increasing > 1.0 mm/year. Fast-growing nodules represented 17.2% of the cohort, and were more frequent in patients younger than 50 years (OR 2.2 [1.2-4.1], P = 0.016), and in larger nodules (2.0-2.9 cm, OR 3.5 [1.7-7.1], P = 0.001; >3.0 cm, OR 4.4 [1.8-10.4], P = 0.001 vs reference 1-1.9 cm). In a multiple regression model, nodule growth at 3 years at an average growth rate over 0.2 mm/year over 3 years since initial evaluation was an independent predictor of longer-term fast nodule growth, even after adjusting for age, biological sex, TSH level, and nodule size (P < 0.001). CONCLUSION: The natural history of benign nodule growth is diverse, with over 80% of nodules demonstrating minimal to no growth long-term. Nearly 20% of cytologically benign nodules may exhibit a fast, continued growth pattern, which can be predicted by the 3-year growth rate pattern. These findings can help inform decision making for tailored benign nodule follow-up and monitoring.

Clinical experience following implementation of routine SPECT-CT imaging following 131-iodine administration for thyroid cancer.

Background: Planar scintigraphy has long been indicated in patients receiving I-131 therapy for thyroid cancer to determine the anatomic location of metastases. We studied our experience upon implementing additional single-photon emission (SPECT)-CT scanning in these patients. Method: We performed a retrospective study of consecutive adult patients with newly diagnosed thyroid cancer treated with I-131 between 2011 and 2017. Radiologic findings detected with planar scintigraphy alone vs those identified with SPECT-CT scanning were primary endpoints. Result: In this study, 212 consecutive patients with thyroid cancer were analyzed in two separate cohorts (107 planar scintigraphy alone and 105 planar scintigraphy with SPECT-CT). The addition of SPECT-CT resulted in more findings, both thyroid-related and incidental. However, we identified only 3 of 21 cases in which SPECT-CT provided an unequivocal additional benefit by changing clinical management beyond planar scintigraphy alone. No difference in the detection of distant metastatic disease or outcome was identified between cohorts. Conclusion: Synergistic SPECT-CT imaging in addition to planar nuclear scintigraphy adds limited clinical value to thyroid cancer patients harboring a low risk of distant metastases, while frequently identifying clinically insignificant findings. These data from a typical cohort of patients receiving standard thyroid cancer care provide insight into the routine use of SPECT-CT in such patients.

Thyroid Nodule Shape Independently Predicts Risk of Malignancy.

CONTEXT: Predictive models of thyroid nodule cancer risk are presently based upon nodule composition, echogenicity, margins, and the presence of microcalcifications. Nodule shape has shown promise to be an additive factor helping determine the need for nodule biopsy. OBJECTIVE: We sought to determine if calculation of a nodule's spherical shape independently associates with cancer risk. METHODS: This prospective cohort study, conducted at a single large academic healthcare system in the United States, included patients with 1 or 2 clinically relevant thyroid nodules (predominantly solid and over 1 cm) presenting for diagnostic evaluation. Thyroid ultrasound, cytological evaluation with fine-needle biopsy, and/or histopathological examination on occasion of thyroid surgery were performed. We calculated the nodule's long to short ratio (spherical shape), and its association with tissue proven benign or malignant endpoints. RESULTS: The long to short nodule ratio was significantly lower in malignant compared to benign nodules indicating greater risk of malignancy in more spherical nodules (1.63 ±â€…0.38 for malignant nodules vs 1.74 ±â€…0.47 for benign, P < 0.0001). The risk of malignancy continually increased as the long to short ratio approached a purely spherical ratio of 1.0 (ratio > 2.00, 14.6% cancer; ratio 1.51-2.00, 19.7%; ratio 1.00-1.50, 25.5%, P < 0.0001). In multiple regression analysis, younger age, male sex, and nodule's spherical shape were each independently associated with cancer risk. CONCLUSION: The more a thyroid nodule is spherically shaped, as indicated by a long to short ratio approaching 1.0, the greater its risk of malignancy. This was independent of age, sex, and nodule size. Incorporating a nodule's sphericity in the risk stratification systems may improve individualized clinical decision making.

Point of Care Measurement of Body Mass Index and Thyroid Nodule Malignancy Risk Assessment.

Background: Large scale epidemiology studies have suggested obesity may increase the risk of thyroid cancer, though no prospective analyses using real-world measurement of BMI at a time proximate to initial thyroid nodule evaluation have been performed. Methods: We performed a prospective, cohort analysis over 3 years of consecutive patients presenting for thyroid nodule evaluation. We measured BMI proximate to the time of initial evaluation and correlated this with the final diagnosis of benign or malignant disease. We further correlated patient BMI with aggressivity of thyroid cancer, if detected. Results: Among 1,259 consecutive patients with clinically relevant nodules, 199(15%) were malignant. BMI averaged 28.6 kg/m2 (SD: 6.35, range:16.46-59.26). There was no correlation between the measurement of BMI and risk of thyroid cancer (p=0.58) as mean BMI was 28.9 kg/m2 and 28.6 kg/m2 in cancerous and benign cohorts, respectively. Similarly, BMI did not predict aggressive thyroid cancer (p=0.15). While overall nodule size was associated with increased BMI (p<0.01), these data require further validation as obesity may hinder nodule detection until large. Conclusion: In contrast to findings published from large scale association studies drawn from national databases, these prospective data of consecutive patients presenting for nodule evaluation detect no association of obesity (as measured by BMI) with thyroid cancer. Real time measurement of BMI at the time of thyroid nodule evaluation does not contribute to cancer risk assessment.

Performance of Thyroid-Stimulating Immunoglobulin Bioassay and Thyrotropin-Binding Inhibitory Immunoglobulin Assay for the Diagnosis of Graves' Disease in Patients With Active Thyrotoxicosis.

OBJECTIVE: Graves' disease (GD) is caused by the stimulation of thyrotropin receptors by autoantibodies. We compared the diagnostic accuracy of the thyroid-stimulating immunoglobulin (TSI) bioassay and thyrotropin-binding inhibitory immunoglobulin (TBII) assay in differentiating GD from other causes of thyrotoxicosis. METHODS: We retrospectively evaluated 493 patients with thyrotoxicosis who were tested with the third-generation TSI and TBII assays simultaneously. Patients were classified according to the clinical, histopathologic, and imaging criteria into the following groups: positive reference group (PRG) (patients with GD), negative reference group (NRG) (patients without GD), and inconclusive group (patients without a definitive diagnosis). RESULTS: TSI and TBII assays were concordant in 88% of the cases and showed a strong positive correlation (rs = 0.844, P < .01). When analyzed collectively, TSI and TBII assays confirmed the diagnosis of GD in 79% of the PRG cases and excluded GD in 92.5% of patients in NRG. Combined TSI and TBII assays or TBII assay alone showed similar accuracy to the diagnosis of GD (81.4% and 77.5%, respectively). Tests in 40 of 191 patients in PRG were negative for both TSI and TBII assays, whereas 3 of 40 cases in NRG had at least 1 positive thyrotropin receptor antibody test. False-negative cases were associated with subclinical hyperthyroidism, normal radionuclide uptake, longer duration of thyrotoxicosis, and absence of goiter or Graves' ophthalmopathy. CONCLUSION: TSI and TBII assays showed similar performance in differentiating GD from other causes of thyrotoxicosis in a real-world sample of patients with active thyrotoxicosis. In combination, both tests showed little benefit compared with the TBII assay alone. Thyrotropin receptor antibody assay results should be carefully interpreted in patients with mild GD or longstanding disease.

Oncogenic Mutations in PI3K/AKT/mTOR Pathway Effectors Associate with Worse Prognosis in BRAFV600E -Driven Papillary Thyroid Cancer Patients.

PURPOSE: The extent to which routine genomic sequencing can identify relevant secondary genomic alterations among BRAFV600E -mutant papillary thyroid carcinoma (PTC) is unknown. Such markers would prove highly valuable for prognostic purposes. EXPERIMENTAL DESIGN: We reviewed clinicopathologic data of 225 patients with BRAFV600E -mutant PTC and integrated them with genomic data derived from targeted next-generation sequencing (NGS) on tumor specimens. We defined patient subgroups based on bona fide secondary oncogenic events (separate from BRAFV600E ) and compared their clinical features and outcomes with those without additional oncogenic alterations. RESULTS: Additional oncogenic alterations were identified in 16% of tumors. Patients in the "BRAF+additional mutations" group were more likely to be at high American Thyroid Association (ATA) risk of recurrence (48.6% vs. 17.6%; P = 0.0009), had larger baseline tumor (2.7 vs. 1.9 cm; P = 0.0005) and more advanced stage at presentation (14.3% vs. 1.1% stage 4; P < 0.0001). Importantly, over a 65-month follow-up, disease-specific mortality (DSM) was increased when additional mutations were identified (13.8% vs. 1.4% in the BRAF-only group; P = 0.005). Separately, we identified a subcluster of patients harboring oncogenic mutations in key effectors of the PI3K/AKT/mTOR pathway, which were independently associated with DSM (OR = 47.9; 95% confidence interval, 3.5-1,246.5; P = 0.0043). CONCLUSIONS: Identification of additional PIK3/AKT/mTOR alterations in patients with BRAFV600E -mutant PTC provides important and actionable prognostic risk stratification. These data support genomic profiling of PTC tumors to inform prognosis and clinical strategy.

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.

Severity of Proteinuria Is Directly Associated With Risk of Hypothyroidism in Adults.

CONTEXT: Proteinuria can cause or exacerbate hypothyroidism, possibly due to urinary loss of protein-bound thyroid hormone. However, the precise relationship between proteinuria and hypothyroidism remains unclear. OBJECTIVE: This work aimed to determine the prevalence of hypothyroidism in patients with proteinuria and the relationship between hypothyroidism and degree of proteinuria. DESIGN: A retrospective cohort study was conducted from December 1979 to March 2015. SETTING: This study was conducted at a large academic hospital. PATIENTS: All paired samples of urine protein and serum thyrotropin (TSH), measured within 24 hours, were obtained from adults (age > 18 years) with at least one instance of urine protein greater than 0.2 g/day or mg/mg creatinine. MAIN OUTCOME MEASURES: Samples were stratified by urine protein tertile. Mean TSH and risk of TSH elevation were compared among tertiles using analysis of covariance and generalized estimating equations controlled for age, sex, samples per patient, and levothyroxine treatment. RESULTS: A total of 2676 samples were identified from 2136 patients. Mean ±â€…SE TSH (mIU/L) was increased in the highest tertile of urine protein (> 1.75g/day) compared to the lower 2 tertiles (2.09 ±â€…0.07 vs 1.59 ±â€…0.07, 1.59 ±â€…0.06, P < .001). The highest tertile had a greater prevalence of TSH greater than 5 mIU/L (17.2% vs 10.5%, 11.9%, P < .001) but a similar risk of TSH greater than 5 mIU/L (odds ratio [OR] 1.44; 95% CI, 0.67-3.09, P = .35). The highest tertile also had a higher prevalence (6.2% vs 3.4%, 2.6%, P = .003) and risk (OR 1.72; 95% CI, 1.05-2.84, P = .008) of TSH greater than 10 mIU/L. Similar results were observed when comparing samples with nephrotic-range proteinuria (> 3.5g/day) to those with lesser proteinuria. CONCLUSION: Hypothyroidism is common among adults with proteinuria, and the risk of hypothyroidism is directly related to the severity of proteinuria.

Completion Thyroidectomy is Less Common Following Updated 2015 American Thyroid Association Guidelines.

BACKGROUND: The 2015 American Thyroid Association (ATA) guidelines recommended that low-risk, differentiated thyroid cancers (DTC) between 1 and 4 cm may be treated with thyroid lobectomy alone. We sought to determine the effect of these guideline changes on the rate of completion thyroidectomy (CT) for low-risk DTC and factors influencing surgical decision-making. METHODS: All patients from 2014 to 2018 who received an initial thyroid lobectomy at our institution with final pathology demonstrating DTC were included. Patients were divided into "pre" and "post" guideline cohorts (2014-2015 and 2016-2018, respectively). The rate of CT was compared between the two cohorts. Patient demographics and tumor characteristics were examined for association with CT. RESULTS: A total of 163 patients met study criteria: 63 patients in the 2014-2015 ("pre") and 100 in the 2016-2018 ("post") group. In the "pre" period, 41 (65.1%) patients received CT compared with 43 (43.0%) in the "post" period (p < 0.01)-a 34% decrease in the rate of completion surgery (p < 0.01). Of low-risk patients with DTC between 1 and 4 cm in size, 17 of 35 (48.6%) received CT in the "pre" period compared with 15 of 60 (25.0%) in the post period-a 48.6% decrease in the rate of completion surgery (p = 0.02). Greater tumor size, capsular invasion, and multifocality were associated with CT in low-risk "post" guideline patients (p < 0.05 for all). CONCLUSIONS: The rate of CT decreased significantly by 48.6% for low-risk patients with DTC between 1 and 4 cm, demonstrating recognition of the 2015 ATA guidelines. However, 25% of these patients underwent CT, suggesting additional factors influencing the decision for further treatment.

Unexpected Pathogenic RET p.V804M Variant Leads to the Clinical Diagnosis and Management of Medullary Thyroid Carcinoma.

BACKGROUND RET p.V804M is a known activating oncogenic variant that confers an increased risk for medullary thyroid carcinoma (MTC). Based on age-specific penetrance, the American Thyroid Association (ATA) categorizes this variant as posing moderate risk. Therefore, ATA guidelines endorse prophylactic thyroidectomy for carriers in childhood (by age 5-10 years) or adulthood, or when the serum calcitonin level becomes elevated. The recommendation for thyroidectomy is increasingly controversial due to the recently reported low penetrance of the RET p.V804M variant in a large unbiased ascertainment cohort. CASE REPORT We describe the unexpected identification of this variant in a 62-year-old woman undergoing broad, multigene cancer panel testing for her personal and family history of breast cancer. There was no known family history of MTC. Biochemical screening prompted by the RET p.V804M result revealed a mildly elevated serum calcitonin. Pathology examination of her thyroidectomy specimen revealed multifocal medullary thyroid microcarcinoma; her sibling's prophylactic thyroidectomy after a RET p.V840M-positive result similarly revealed early-stage MTC. CONCLUSIONS This report demonstrates the value of genetic counseling, shared decision-making, cascade testing, and timely thyroidectomy in the management of a patient with an unexpected RET p.V804M result.

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).

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.

Discordance of serological and sonographic markers for Hashimoto's thyroiditis with gold standard histopathology.

OBJECTIVE: To investigate the concordance of serologic and sonographic evidence of Hashimoto's thyroiditis with its gold standard histopathologic identification. DESIGN: We performed a retrospective analysis on a cohort of 825 consecutive patients in whom TPOAb and thyroid ultrasound were performed, and in whom thyroid nodule evaluation led to surgical and histopathologic analysis. The presence or absence of Hashimoto's thyroiditis on histopathology was correlated with serologic and sonographic markers. We further assessed the impact of low versus high titers of TPOAb upon this concordance. RESULTS: Of 825 patients, 277 (33.5%) had histologic confirmation of Hashimoto's thyroiditis, 235 patients (28.4%) had elevated serum levels of TPOAb, and 197 (23.8%) had sonographic evidence of diffuse heterogeneity. Of those with histopathologic evidence, only 64% had elevated TPOAb (sensitivity: 63.9%; specificity: 89.4%), while only 49% were sonographically diffusely heterogeneous (sensitivity: 49.1%; specificity: 88.9%). A subset of only 102 of 277 (37%) with histologically proven Hashimoto's thyroiditis was positive for both TPOAb and diffusely heterogeneous. Concordance analysis demonstrated that TPOAb and histopathology had higher agreement (κ = 0.55) than did ultrasound and histopathology (κ = 0.40) for the diagnosis of Hashimoto's thyroiditis. Higher titers of TPOAb correlated with a higher likelihood of Hashimoto's thyroiditis, with a best cutoff of 2.11-fold the upper normal level of TPOAb. CONCLUSION: Only moderate concordance exists between serological evidence of Hashimoto's thyroiditis and histopathologic findings, though it increases with higher TPOAb concentration. Diffuse heterogeneity on ultrasound is a less-sensitive diagnostic tool than elevated TPOAb.

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.