Comparison of the collection approaches of 2 large thyroid fine-needle aspiration practices reveals differing advantages for cytology and molecular testing adequacy rates.

INTRODUCTION: At our institution, almost all thyroid fine-needle aspiration (FNA) procedures are performed by either Endocrinology or Radiology personnel. In this study, we compared the cytology and molecular adequacy rates of these 2 thyroid FNA practices, which differ on several aspects of specimen procurement. MATERIALS AND METHODS: All thyroid FNA specimens from Endocrinology and Radiology practices between September 2008 and December 2016 were included. Over this time frame, the molecular testing modality transitioned from polymerase chain reaction (PCR)-based (7-gene panel era) to next generation sequencing (NGS)-based (ThyroSeq era). In measuring cytology adequacy, the Bethesda System unsatisfactory rate was determined. Molecular adequacy was categorized as Optimal, Limited Thyroid Epithelial Cells, Limited Nucleic Acids, or Failed. These parameters were compared for the 2 practices. RESULTS: The study cohorts comprised 5810 specimens from Endocrinology and 4597 from Radiology. More Endocrinology specimens were satisfactory for cytology diagnosis than those from Radiology (94.7% versus 90.0%, P < 0.001). For molecular adequacy, fewer Endocrinology specimens were optimal than specimens from Radiology for both the 7-gene panel era (76.2% versus 82.9%, P < 0.001) and the ThyroSeq era (88.1% versus 91.9%, P = 0.049). CONCLUSIONS: The 2 thyroid FNA practices varied inversely in their adequacy rates for cytology and molecular testing. Had one practice been superior for both cytology and molecular adequacy, a recommendation for the method of choice would have been straightforward. However, our results show that optimization of FNA practice for the current practice of thyroid cytology requires further investigation due to the complex nature of specimen procurement.

Benign call rate and molecular test result distribution of ThyroSeq v3.

BACKGROUND: The benign call rate (BCR) is the percentage of cytomorphologically indeterminate cases with subsequent benign or negative molecular results. For rule-out tests, the BCR is an important parameter because these molecular "negative" cases may be managed similarly to those with a benign cytology diagnosis. Although earlier versions of ThyroSeq molecular tests were less effective in excluding malignancy, the extensively expanded v3 version with a high negative predictive value is considered to represent a rule-out test. In the current study, the authors evaluated the BCR and the overall molecular result distribution of ThyroSeq v3. METHODS: All indeterminate thyroid fine-needle aspiration cases (except those deemed suspicious for malignancy) with available ThyroSeq v3 results from November 2017 to June 2018 were retrieved from the cytopathology files. Because the ThyroSeq v3 genomic classifier was designed for thyroid follicular-derived lesions, cases in which parathyroid and medullary carcinoma molecular markers were detected and those that were inadequate or limited for molecular testing were excluded from the study. For the remaining cases, the indeterminate diagnoses were correlated with molecular and histologic results. RESULTS: Among the 224 indeterminate cases (except those deemed suspicious for malignancy), the overall ThyroSeq v3 molecular test BCR was 74.1% (166 of 224 cases). The category of atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) had higher BCRs compared with the other indeterminate diagnostic categories. RAS mutations were the most common positive results. CONCLUSIONS: The high BCR demonstrates that ThyroSeq v3 is potentially effective in sparing the large majority of indeterminate cases with "negative" results from surgery while offering risk assessment for the positive cases and guiding clinical management.

Correct extent of thyroidectomy is poorly predicted preoperatively by the guidelines of the American Thyroid Association for low and intermediate risk thyroid cancers.

BACKGROUND: Recent guidelines from the American Thyroid Association recommend thyroid lobectomy for intrathyroidal differentiated thyroid cancers <4 cm. Our aim was to examine histology from patients with cytologic results that were positive or suspicious for malignancy to assess the extent of initial thyroidectomy based on criteria from the 2015 American Thyroid Association guidelines. METHODS: We studied consecutive patients who had either a positive or suspicious for malignancy cytologic diagnosis and under prior American Thyroid Association guidelines underwent initial total thyroidectomy ± lymphadenectomy. RESULTS: Among 447 patients, high-risk features necessitating total thyroidectomy were present in 19% (72/380) of positive and 15% (10/67) of suspicious for malignancy patients (P = .5). Intermediate-risk features on histology were identified postoperatively in 46% (175/380) with positive and 15% (18/67) with suspicious for malignancy fine-needle aspiration results. In multivariable analysis, preoperative factors associated with intermediate-risk disease included age ≥45 years, women, larger tumor size, positive fine-needle aspiration cytology, and BRAF V600E or RET/PTC positivity. CONCLUSION: When patients are considered for lobectomy under the 2015 American Thyroid Association guidelines, ~ 60% with positive and 30% with suspicious for malignancy cytology would need completion thyroidectomy based on intermediate-risk disease. The cost and risk implications of the new American Thyroid Association strategy were substantial and better tools are needed to improve preoperative risk stratification.

The influence of the noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) resection diagnosis on the false-positive thyroid cytology rate relates to quality assurance thresholds and the application of NIFTP criteria.

BACKGROUND: Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a newly defined entity and recent studies have suggested a decrease of a few percentage points in the rate of malignancy (ROM) for the positive-for-malignancy (PFM) cytology category as a result of NIFTP implementation. However, the distinction between a diagnosis of PFM and one of suspicious for malignancy (SFM) may depend on a variety of factors. In the current study, the authors investigated the ROM for the PFM and SFM diagnoses before and after histologic NIFTP reclassification. METHODS: Cytology cases with PFM and SFM diagnoses and subsequent surgical resection specimens were searched in the files of the study institution from September 2008 to September 2016. The surgical pathology cases of noninvasive encapsulated follicular variant of papillary thyroid carcinoma were reexamined to determine whether they qualified for NIFTP. The distinct ROMs for the PFM and SFM cases were calculated accordingly. RESULTS: The authors' search identified 338 cases of PFM and 139 cases of SFM with a resection outcome. Before NIFTP reclassification, the PFM cases had a ROM of 99.4%; after NIFTP reclassification, the ROM was 99.1% (P = .6861). The ROM of the SFM cases decreased from 75.5% to 66.9% with NIFTP reclassification (P = .1402). One case in the PFM group and 6 cases in the SFM group could not be verified due to insufficient sampling. CONCLUSIONS: In the current large series, NIFTP reclassification did not appear to significantly alter the high ROM for the PFM diagnosis. The authors attribute this finding to a strict quality assurance policy, an emphasis on key cytologic criteria, and systematic application of the NIFTP criteria to follicular-patterned lesions. Cancer Cytopathol 2017;125:692-700. © 2017 American Cancer Society.

Preoperative detection of RAS mutation may guide extent of thyroidectomy.

BACKGROUND: Preoperative detection of RAS mutations can contribute to cancer risk assessment in indeterminate thyroid nodules, although RAS is not always associated with malignancy. METHODS: Fine-needle aspiration samples classified in 1 of 3 indeterminate cytology categories were prospectively tested for N-, H-, and K-RAS mutations using next-generation sequencing assay. RESULTS: In the study, 93 patients with 94 nodules had preoperative RAS detected, of whom 86 patients had an operation (69% total thyroidectomy, 29% lobectomy). In total, 76% of RAS-positive nodules were malignant and follicular variant papillary thyroid cancer was the most common cancer type (83%). HRAS mutations had the greatest risk of cancer (92%) followed by NRAS (74%) and KRAS (64%; P = .05). No preoperative variables were associated with malignancy including age (P = .07), sex (P = .49), RAS isoform (P = .05), mutational allelic frequency (P = .49), nodule size (P = .14), cytology category (P = .63), or ultrasound bilaterality (P = .24), multifocality (P = .23), or presence of ≥1 suspicious feature (P = .86). Only 60% of patients with a unifocal nodule on ultrasound had single focus low-risk encapsulated follicular variant papillary thyroid cancer or benign disease. CONCLUSION: Preoperative RAS mutation detection in thyroid nodules carries a substantial risk of cancer with a greater risk associated with HRAS and NRAS. Most RAS malignancies are follicular variant papillary thyroid cancer, which may inform the extent of operation.

Impact of the Multi-Gene ThyroSeq Next-Generation Sequencing Assay on Cancer Diagnosis in Thyroid Nodules with Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance Cytology.

BACKGROUND: Fine-needle aspiration (FNA) cytology is a common approach to evaluate thyroid nodules. It offers definitive diagnosis of a benign or malignant nodule in the majority of cases. However, 10-25% of nodules yield one of three indeterminate cytologic diagnoses, leading to suboptimal management of these patients. Atypia of undetermined significance/follicular lesion of undermined significance (AUS/FLUS) is a common indeterminate diagnosis, with the cancer risk ranging from 6% to 48%. This study assessed whether a multi-gene next-generation sequencing (NGS) assay can offer significant improvement in diagnosis in AUS/FLUS nodules. METHODS: From May 2014 to March 2015, 465 consecutive FNA samples with the cytologic diagnosis of AUS/FLUS underwent prospective molecular testing using the ThyroSeq v2.1 panel. The panel included 14 genes analyzed for point mutations and 42 types of gene fusions occurring in thyroid cancer. In addition, eight genes were assessed for expression in order to evaluate the cell composition of FNA samples. Ninety-eight (21%) of these nodules had definitive surgical (n = 96) or nonsurgical (n = 2) follow-up and were used to determine the assay performance. RESULTS: Among 465 AUS/FLUS nodules, three were found to be composed of parathyroid cells and 462 of thyroid follicular cells. Of the latter, 31 (6.7%) were positive for mutations. The most frequently mutated genes were NRAS and HRAS, and overall point mutations in seven different genes and five types of gene fusions were identified in these nodules. Among 98 nodules with known outcome, histologic analysis revealed 22 (22.5%) cancers. ThyroSeq v2.1 was able to classify 20/22 cancers correctly, showing a sensitivity of 90.9% [confidence interval (CI) 78.8-100], specificity of 92.1% [CI 86.0-98.2], positive predictive value of 76.9% [CI 60.7-93.1], and negative predictive value of 97.2% [CI 78.8-100], with an overall accuracy of 91.8% [CI 86.4-97.3]. CONCLUSIONS: The results of the study demonstrate that the ThyroSeq v2.1 multi-gene NGS panel of molecular markers provides both high sensitivity and high specificity for cancer detection in thyroid nodules with AUS/FLUS cytology, which should allow improved management for these patients.

Significance of what is not sampled: Characteristics of thyroid nonmicrocarcinomas (>1.0 cm) that were not targeted.

BACKGROUND: Although most unsuspected thyroid carcinomas qualify as microcarcinomas (≤1 cm), larger, nontargeted carcinomas may be found also. This study evaluated the significance of these nonmicrocarcinomas (>1 cm) in the setting of a large-volume thyroid practice. METHODS: Thyroid resection specimens from May 2007 to December 2012 were reviewed. For these cases, the pathologic characteristics of nontargeted carcinomas larger than 1.0 cm were evaluated. Those interpreted as intrathyroidal metastases were not included in this study. Specifically, the histologic classification, size, and molecular features were documented. RESULTS: From a total of 4815 thyroid resections and 9279 thyroid fine-needle aspiration procedures that were performed during the study period, 27 nontargeted nonmicrocarcinomas were identified (0.6% of resection cases) in 26 patients. The histologic classifications were as follows: follicular variant of papillary carcinoma (n = 19), classic papillary carcinoma (n = 3), papillary carcinoma with oncocytic features (n = 1), tall-cell variant of papillary carcinoma (n = 2), and follicular carcinoma (n = 2). The size parameters were as follows: mean, 1.9 cm; median, 1.4 cm; and range, 1.1 to 7.0 cm. RAS and BRAF mutations were identified in 8 and 7 cases, respectively (71% of the cases tested with a 7-gene panel), whereas 6 cases showed no mutation. Molecular information was not available for 6 cases. CONCLUSIONS: In the authors' experience, nontargeted thyroid nonmicrocarcinomas (>1 cm) are rare (0.6%), and the majority are low-grade carcinomas. The likelihood of finding one of the common mutations (71%) is comparable to the likelihood for thyroid carcinomas in general (∼70%).

Tumor genotype determines phenotype and disease-related outcomes in thyroid cancer: a study of 1510 patients.

OBJECTIVES: To correlate thyroid cancer genotype with histology and outcomes. BACKGROUND: The prognostic significance of molecular signature in thyroid cancer (TC) is undefined but can potentially change surgical management. METHODS: We reviewed a consecutive series of 1510 patients who had initial thyroidectomy for TC with routine testing for BRAF, RAS, RET/PTC, and PAX8/PPARG alterations. Histologic metastatic or recurrent TC was tracked for 6 or more months after oncologic thyroidectomy. RESULTS: Papillary thyroid cancer (PTC) was diagnosed in 97% of patients and poorly differentiated/anaplastic TC in 1.1%. Genetic alterations were detected in 1039 (70%); the most common mutations were BRAFV600E (644/1039, 62%), and RAS isoforms (323/1039, 31%). BRAFV600E-positive PTC was often conventional or tall cell variant (58%), with frequent extrathyroidal extension (51%) and lymph node metastasis (46%). Conversely, RAS-positive PTC was commonly follicular variant (87%), with infrequent extrathyroidal extension (4.6%) and lymph node metastasis (5.6%). BRAFV600E and RET/PTC-positive PTCs were histologically similar. Analogously, RAS and PAX8/PPARG-positive PTCs were histologically similar. Compared with RAS or PAX8/PPARG-positive TCs, BRAFV600E or RET/PTC-positive TCs were more often associated with stage III/IV disease (40% vs 15%, P < 0.001) and recurrence (10% vs 0.7%, P < 0.001; mean follow-up 33 ± 21 mo). Distant metastasis was highest in patients with RET/PTC-positive TC (10.8%, P = 0.02). CONCLUSIONS: In this large study of prospective mutation testing in unselected patients with TC, molecular signature was associated with distinctive phenotypes including cancers, with higher risks of both distant metastasis and early recurrence. Preoperative genotype provides valuable prognostic data to appropriately inform surgery.

Highly accurate diagnosis of cancer in thyroid nodules with follicular neoplasm/suspicious for a follicular neoplasm cytology by ThyroSeq v2 next-generation sequencing assay.

BACKGROUND: Fine-needle aspiration (FNA) cytology is a common approach to evaluating thyroid nodules, although 20% to 30% of FNAs have indeterminate cytology, which hampers the appropriate management of these patients. Follicular (or oncocytic) neoplasm/suspicious for a follicular (or oncocytic) neoplasm (FN/SFN) is a common indeterminate diagnosis with a cancer risk of approximately 15% to 30%. In this study, the authors tested whether the most complete next-generation sequencing (NGS) panel of genetic markers could significantly improve cancer diagnosis in these nodules. METHODS: The evaluation of 143 consecutive FNA samples with a cytologic diagnosis of FN/SFN from patients with known surgical outcomes included 91 retrospective samples and 52 prospective samples. Analyses were performed on a proprietary sequencer using the targeted ThyroSeq v2 NGS panel, which simultaneously tests for point mutations in 13 genes and for 42 types of gene fusions that occur in thyroid cancer. The expression of 8 genes was used to assess the cellular composition of FNA samples. RESULTS: In the entire cohort, histologic analysis revealed 104 benign nodules and 39 malignant nodules. The most common point mutations involved the neuroblastoma RAS viral oncogene homolog (NRAS), followed by the Kirsten rat sarcoma viral oncogene homolog (KRAS), the telomerase reverse transcriptase (TERT) gene, and the thyroid-stimulating hormone receptor (TSHR) gene. The identified fusions involved the thyroid adenoma associated (THADA) gene; the peroxisome proliferator-activated receptor γ (PPARG) gene; and the neurotrophic tyrosine kinase, receptor, type 3 (NTRK3) gene. Performance characteristics were similar in the retrospective and prospective groups. Among all FN/SFN nodules, preoperative ThyroSeq v2 performed with 90% sensitivity (95% confidence interval [CI], 80%-99%), 93% specificity (95% CI, 88%-98%), a positive predictive value of 83% (95% CI, 72%-95%), a negative predictive value of 96% (95% CI, 92%-100%), and 92% accuracy (95% CI, 88%-97%). CONCLUSIONS: The current results indicate that comprehensive genotyping of thyroid nodules using a broad NGS panel provides a highly accurate diagnosis for nodules with FN/SFN cytology and should facilitate the optimal management of these patients.

Thyroid nodules with KRAS mutations are different from nodules with NRAS and HRAS mutations with regard to cytopathologic and histopathologic outcome characteristics.

BACKGROUND: Mutations in the RAS gene in the thyroid gland result in the activation of signaling pathways and are associated with a follicular growth pattern and the probability of a carcinoma outcome ranging from 74% to 87%. In the current study, the authors investigated the cytopathologic and histopathologic features of common RAS mutation subtypes. METHODS: Malignant, indeterminate, and selected benign thyroid cytology cases were tested prospectively for the presence of NRAS61, HRAS61, and KRAS12/13 mutations. For each case, the Bethesda System for thyroid cytopathology diagnosis, additional cytologic descriptors, and surgical pathology outcomes were documented. The Fisher exact test and Wilcoxon 2-sample test were used for statistical comparison between the groups. RESULTS: A total of 204 thyroid fine-needle aspiration cases with RAS mutations (93.6% of which were associated with indeterminate cytopathology diagnoses) and corresponding surgical pathology resection specimens were identified. The KRAS12/13 mutation was associated with a significantly lower carcinoma outcome (41.7%) when compared with HRAS61 (95.5%) and NRAS61 (86.8%) mutations (P<.0001). Furthermore, oncocytic change was observed in a significantly higher percentage of cytology and resection specimens with KRAS12/13 mutations (66.7% and 75.0%, respectively) in comparison with those with HRAS61 (4.5% and 4.5%, respectively) and NRAS61 (15.4% and 14.7%, respectively) mutations (P<.0001). RAS mutations also were identified in cases of poorly differentiated carcinoma (NRAS61), anaplastic carcinoma (HRAS61), and medullary thyroid carcinoma (HRAS61 and KRAS12/13). CONCLUSIONS: Subclassification of RAS mutations in conjunction with cytopathologic evaluation improves presurgical risk stratification, provides better insight into lesional characteristics, and may influence patient management. In particular, KRAS12/13-mutated thyroid nodules were found to be different from HRAS61-mutated and NRAS61-mutated nodules with regard to cytopathologic and surgical outcome characteristics.

A clinical algorithm for fine-needle aspiration molecular testing effectively guides the appropriate extent of initial thyroidectomy.

OBJECTIVE: To test whether a clinical algorithm using routine cytological molecular testing (MT) promotes initial total thyroidectomy (TT) for clinically significant thyroid cancer (sTC) and/or correctly limits surgery to lobectomy when appropriate. BACKGROUND: Either TT or lobectomy is often needed to diagnose differentiated thyroid cancer. Determining the correct extent of initial thyroidectomy is challenging. METHODS: After implementing an algorithm for prospective MT of in-house fine-needle aspiration biopsy specimens, we conducted a single-institution cohort study of all patients (N = 671) with nonmalignant cytology who had thyroidectomy between October 2010 and March 2012, cytological diagnosis using 2008 Bethesda criteria, and 1 or more indications for thyroidectomy by 2009 American Thyroid Association guidelines. sTC was defined by histological differentiated thyroid cancer of 1 cm or more and/or lymph node metastasis. Cohort 2 patients did not have MT or had unevaluable results. In cohort 1, MT for a multigene mutation panel was performed for nonbenign cytology, and positive MT results indicated initial TT. RESULTS: MT guidance was associated with a higher incidence of sTC after TT (P = 0.006) and a lower rate of sTC after lobectomy (P = 0.03). Without MT results, patients with indeterminate (follicular lesion of undetermined significance/follicular or oncocytic neoplasm) cytology who received initial lobectomy were 2.5 times more likely to require 2-stage surgery for histological sTC (P < 0.001). In the 501 patients with non-sTC for whom lobectomy was the appropriate extent of surgery, lobectomy was correctly performed more often with routine preoperative MT (P = 0.001). CONCLUSIONS: Fine-needle aspiration biopsy MT for BRAF, RAS, PAX8-PPARγ, and RET-PTC expedites optimal initial surgery for differentiated thyroid cancer, facilitating succinct definitive management for patients with thyroid nodules.

Effects of testosterone and growth hormone on the structural and mechanical properties of bone by micro-MRI in the distal tibia of men with hypopituitarism.

CONTEXT: Severe deficiencies of testosterone (T) and GH are associated with low bone mineral density (BMD) and increased fracture risk. Replacement of T in hypogonadal men improves several bone parameters. Replacement of GH in GH-deficient men improves BMD. OBJECTIVE: Our objective was to determine whether T and GH treatment together improves the structural and mechanical parameters of bone more than T alone in men with hypopituitarism. DESIGN AND SUBJECTS: This randomized, prospective, 2-year study included 32 men with severe deficiencies of T and GH due to panhypopituitarism. INTERVENTION: Subjects were randomized to receive T alone (n = 15) or T and GH (n = 17) for 2 years. MAIN OUTCOME MEASURES: We evaluated magnetic resonance microimaging-derived structural (bone volume fraction [BVF] and trabecular thickness) and mechanical (axial stiffness [AS], a measure of bone strength) properties of the distal tibia at baseline and after 1 and 2 years of treatment. RESULTS: Treatment with T and GH did not affect BVF, thickness, or AS differently from T alone. T treatment in all subjects for 2 years increased trabecular BVF by 9.6% (P < .0001), trabecular thickness by 2.6% (P < .001), and trabecular AS by 9.8% (P < .001). In contrast, testosterone treatment in all subjects significantly increased cortical thickness by 2.4% (P < .01) but decreased cortical BVF by -4.7% (P < .01) and cortical AS by -6.9% (P < .01). CONCLUSION: Combined T and GH treatment of men with hypopituitarism for 2 years did not improve the measured structural or mechanical parameters of the distal tibia more than T alone. However, testosterone significantly increased the structural and mechanical properties of trabecular bone but decreased most of these properties of cortical bone, illustrating the potential importance of assessing trabecular and cortical bone separately in future studies of the effect of testosterone on bone.

Thyroid nodules (≥4 cm): can ultrasound and cytology reliably exclude cancer?

BACKGROUND: Whether a threshold nodule size should prompt diagnostic thyroidectomy remains controversial. We examined a consecutive series of patients who all had thyroidectomy for a ≥4 cm nodule to determine (1) the incidence of thyroid cancer (TC) and (2) if malignant nodules could accurately be diagnosed preoperatively by ultrasound (US), fine needle aspiration biopsy (FNAB) cytology and molecular testing. METHODS: As a prospective management strategy, 361 patients with 382 nodules ≥4 cm by preoperative US had thyroidectomy from 1/07 to 3/12. RESULTS: The incidence of a clinically significant TC within the ≥4 cm nodule was 22 % (83/382 nodules). The presence of suspicious US features did not discriminate malignant from benign nodules. Moreover, in 86 nodules ≥4 cm with no suspicious US features, the risk of TC within the nodule was 20 %. US-guided FNAB was performed for 290 nodules, and the risk of malignancy increased stepwise from 10.4 % for cytologically benign nodules, 29.6 % for cytologically indeterminate nodules and 100 % for malignant FNAB results. Molecular testing was positive in 9.3 % (10/107) of tested FNAB specimens, and all ten were histologic TC. CONCLUSIONS: In a large consecutive series in which all ≥4 cm nodules had histology and were systematically evaluated by preoperative US and US-guided FNAB, the incidence of TC within the nodule was 22 %. The false negative rate of benign cytology was 10.4 %, and the absence of suspicious US features did not reliably exclude malignancy. At minimum, thyroid lobectomy should be strongly considered for all nodules ≥4 cm.

Nodule size is an independent predictor of malignancy in mutation-negative nodules with follicular lesion of undetermined significance cytology.

BACKGROUND: In thyroid nodule fine-needle aspiration (FNA) cytology, the atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS) category has a 5-15% malignancy risk that increases to 85-99% when mutation testing for BRAF, RAS, RET/PTC, or PAX8/PPARγ is positive. However, negative testing does not exclude malignancy. The study objective was to identify clinical and imaging features that predict cancer in mutation-negative AUS/FLUS thyroid nodules. METHODS: All patients were reviewed (April 2007 to April 2009) who had AUS/FLUS cytology, negative prospective molecular testing of FNA, and histopathology. RESULTS: Of the 230 nodules, 12 (5.2%) were malignant in 11 of 190 patients, and known clinical risk factors for thyroid cancer did not predict malignancy. On preoperative imaging, ≥1 suspicious ultrasound feature was identified in 33% of nodules and occurred regardless of histology (P = .23). Malignant mutation-negative AUS/FLUS nodules were larger than benign nodules (mean maximum diameter, 33.6 vs 24.0 mm; P = .007). On multivariate analysis, nodule size remained an independent predictor of malignancy (odds ratio, 1.043; P = .018). We observed no malignancies in 88 mutation-negative AUS/FLUS nodules <18.5 mm. CONCLUSION: Size is an independent predictor of malignancy in mutation-negative AUS/FLUS nodules and the risk increased 4.3% with every millimeter increase in nodule size. Selected patients with small, mutation-negative AUS/FLUS thyroid nodules may be managed with ultrasound surveillance in lieu of thyroidectomy.

"Colloid-rich" follicular neoplasm/suspicious for follicular neoplasm thyroid fine-needle aspiration specimens: cytologic, histologic, and molecular basis for considering an alternate view.

BACKGROUND: Typically, thyroid follicular neoplasm/suspicious for follicular neoplasm (FN/SFN) cases show moderate to marked cellularity and scant or absent colloid. Recently, cases have been noted with microfollicular cellularity in the background of moderate to abundant amount of colloid. The purpose of this study was to compare these "colloid-rich" FN/SFN cases to the typical FN/SFN cases. METHODS: Thyroid cytology specimens with the features of FN/SFN were searched in cytopathology files from September 2008 to June 2012. Cases with absent or minimal colloid were designated "typical colloid-poor" FN/SFN and cases with moderate to abundant colloid were designated "colloid-rich" FN/SFN. From these cases, those with surgical pathology resection follow-up were identified. Cytologic, surgical pathology resection, and molecular features (BRAF, RAS, RET/PTC, and PAX8-PPARγ) were investigated for the typical colloid-poor FN/SFN cases and were compared with those of the colloid-rich FN/SFN cases. RESULTS: Of 431 FN/SFN cases with surgical pathology resection follow-up, 360 (83.5%) cases showed features of typical colloid-poor FN/SFN and 71 (16.5%) cases showed features of colloid-rich FN/SFN. Papillary carcinoma was the most common malignant outcome for the 2 groups. Although the proportion of malignant outcome was similar for the 2 groups, the "colloid-rich" FN/SFN cases showed a greater proportion of nodular hyperplasia among the cases with benign outcome. In addition, the "colloid-rich" FN/SFN cases demonstrated a greater proportion of cases with a mutation. CONCLUSIONS: Approximately one-sixth of cases of FN/SFN show "colloid-rich" features. Comparison to the typical colloid-poor FN/SFN demonstrated similar risk for malignancy but contrasting resection outcome and molecular characteristics.

RAS mutations in thyroid FNA specimens are highly predictive of predominantly low-risk follicular-pattern cancers.

INTRODUCTION: RAS mutations are common in thyroid tumors and confer a high risk of cancer when detected in fine-needle aspiration (FNA) specimens. Specific characteristics of RAS-positive thyroid cancers are not well described. METHODS: From April 2007 to April 2009, 921 consecutive patients undergoing FNA were evaluated prospectively with a panel of molecular markers. Ultrasonographic, cytological, histological, and surgical outcomes were retrospectively assessed. RESULTS: Sixty-eight aspirates from 66 patients were positive for RAS mutations including 63 cytologically indeterminate (93%), 3 malignant (4%), and 2 benign (3%) specimens. Cancer was histologically confirmed in 52 of 63 aspirates (83%) including the following: 46 papillary thyroid cancers, 4 follicular thyroid cancers, 1 medullary cancer, and 1 anaplastic cancer. All 46 RAS-positive papillary thyroid cancers, including 1 metastatic cancer, had follicular variant histology papillary thyroid cancer; only 11 tumors demonstrated vascular/capsular invasion and 4 had infiltrative growth. Of 48 patients with differentiated thyroid cancer, lymph node metastasis was uncommon and bilateral cancer was present in 48%. Only 33% of malignant nodules were suspicious by preoperative ultrasonography. At a mean follow-up of 22 months, 31 of 35 differentiated thyroid cancer patients (89%) have no evidence of recurrence, 4 patients (9%) have detectable thyroglobulin, 1 patient has bone metastases, and both patients with medullary and anaplastic cancer have died. CONCLUSION: Most RAS-positive thyroid cancers have indeterminate cytology, lack suspicious ultrasound features, and are histologically low-grade follicular variant histology papillary thyroid cancer. Lymph node and distant metastases are uncommon but bilateral disease is frequent. Total thyroidectomy should be considered for initial surgical management of most patients with RAS-positive FNA results. The role of prophylactic lymphadenectomy remains unclear.

BRAF mutation detection in indeterminate thyroid cytology specimens: underlying cytologic, molecular, and pathologic characteristics of papillary thyroid carcinoma.

BACKGROUND: BRAF mutations are highly specific for papillary thyroid carcinoma (PTC) and many cytology specimens with BRAF mutations are expected to demonstrate cytologic features typical of PTC. However, indeterminate thyroid cytology cases are inevitable and understanding the significance of the BRAF mutation within the context of the Bethesda System for Reporting Thyroid Cytopathology would be valuable. METHODS: Thyroid cytology cases submitted for conventional cytomorphologic evaluation and BRAF mutational analyses were selected from the authors' cytopathology files from April 2007 to October 2011. From this group, the diagnostic usefulness of BRAF mutations in indeterminate and malignant cases was assessed and analyses of cytologic and histopathologic features associated with the mutations in this gene were performed. RESULTS: A total of 131 cases with a BRAF mutation were identified. Of these, 119 underwent surgical pathology resection follow-up and demonstrated PTC. Approximately 75% of the cases were cytologically diagnosed as being positive for malignancy and these cases were associated with both the classic and tall cell variants of PTC at the time of resection, a greater likelihood of extrathyroidal extension, and the V600E type of BRAF mutation. In contrast, BRAF-mutated cases with diagnoses of atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) and follicular neoplasm/suspicious for follicular neoplasm were found to be more strongly associated with the follicular variant of PTC, a K601E BRAF mutation, and a lower likelihood of extrathyroidal extension. However, a subset of AUS/FLUS cases with the V600E BRAF mutation appeared to represent sampling variability of the classic or tall cell variants of PTC. CONCLUSIONS: Bethesda thyroid diagnoses in the setting of a BRAF mutation reflect differences in PTC subtypes, the nature of cytology specimens, and molecular characteristics.

A combined molecular-pathologic score improves risk stratification of thyroid papillary microcarcinoma.

BACKGROUND: Thyroid papillary microcarcinoma (TPMC) is an incidentally discovered papillary carcinoma that measures ≤1.0 cm in size. Most TPMCs are indolent, whereas some behave aggressively. The objective of the study was to evaluate whether the combination of v-raf murine sarcoma viral oncogene homolog B1 (BRAF) mutation and specific histopathologic features allows risk stratification of TPMC. METHODS: A group aggressive TPMCs was selected based on the presence of lymph node metastasis or tumor recurrence. Another group of nonaggressive tumors included TPMCs matched with the first group for age, sex, and tumor size, but with no extrathyroid spread. A molecular analysis was performed, and histologic slides were scored for multiple histopathologic criteria. A separate validation cohort of 40 TPMCs was evaluated. RESULTS: BRAF mutations were detected in 77% of aggressive TPMCs and in 32% of nonaggressive tumors (P = .001). Several histopathologic features differed significantly between the groups. By using multivariate regression analysis, a molecular-pathologic (MP) score was developed that included BRAF status and 3 histopathologic features: superficial tumor location, intraglandular tumor spread/multifocality, and tumor fibrosis. By adding the histologic criteria to BRAF status, sensitivity was increased from 77% to 96%, and specificity was increased from 68% to 80%. In the independent validation cohort, the MP score stratified tumors into low-risk, moderate-risk, and high-risk groups with the probability of lymph node metastases or tumor recurrence in 0%, 20%, and 60% of patients, respectively. CONCLUSIONS: BRAF status together with several histopathologic features allowed clinical risk stratification of TPMCs. The combined MP risk stratification model was a better predictor of extrathyroid tumor spread than either mutation or histopathologic findings alone.

Impact of mutational testing on the diagnosis and management of patients with cytologically indeterminate thyroid nodules: a prospective analysis of 1056 FNA samples.

CONTEXT: Thyroid nodules are common in adults, but only a small fraction of them is malignant. Fine-needle aspiration (FNA) cytology provides a definitive diagnosis of benign or malignant disease in many cases, whereas about 25% of nodules are indeterminate, hindering most appropriate management. OBJECTIVE: The objective of the investigation was to study the clinical utility of molecular testing of thyroid FNA samples with indeterminate cytology. DESIGN: Residual material from 1056 consecutive thyroid FNA samples with indeterminate cytology was used for prospective molecular analysis that included the assessment of cell adequacy by a newly developed PCR assay and testing for a panel of mutations consisted of BRAF V600E, NRAS codon 61, HRAS codon 61, and KRAS codons 12/13 point mutations and RET/PTC1, RET/PTC3, and PAX8/PPARγ rearrangements. RESULTS: The collected material was adequate for molecular analysis in 967 samples (92%), which yielded 87 mutations including 19 BRAF, 62 RAS, 1 RET/PTC, and five PAX8/PPARγ. Four hundred seventy-nine patients who contributed 513 samples underwent surgery. In specific categories of indeterminate cytology, i.e. atypia of undetermined significance/follicular lesion of undetermined significance, follicular neoplasm/suspicious for a follicular neoplasm, and suspicious for malignant cells, the detection of any mutation conferred the risk of histologic malignancy of 88, 87, and 95%, respectively. The risk of cancer in mutation-negative nodules was 6, 14, and 28%, respectively. Of 6% of cancers in mutation-negative nodules with atypia of undetermined significance/follicular lesion of undetermined significance cytology, only 2.3% were invasive and 0.5% had extrathyroidal extension. CONCLUSION: Molecular analysis for a panel of mutations has significant diagnostic value for all categories of indeterminate cytology and can be helpful for more effective clinical management of these patients.

Both BRAF V600E mutation and older age (≥ 65 years) are associated with recurrent papillary thyroid cancer.

PURPOSE: This study was designed to examine the aggressive features of BRAF-positive papillary thyroid cancer (PTC) and association with age. METHODS: We compared the clinicopathologic parameters and BRAF V600E mutation status of 121 elderly (age ≥65 years) PTC patients who underwent thyroidectomy from January 2007 to December 2009 to a consecutive cohort of 98 younger (age <65 years) PTC patients. RESULTS: Younger and elderly PTC patients had similar incidences of BRAF-positive tumors (41% vs. 38%; p = 0.67). The elderly cohort was more likely to have smaller tumors (mean 1.6 vs. 2.1 cm; p = 0.001), present with advanced TNM stage (36% vs. 19%; p = 0.008), and have persistent/recurrent disease (10% vs. 1%; p = 0.006). BRAF-positive status was associated with PTC that were tall cell variant (p < 0.001), had extrathyroidal extension (p < 0.001), lymph node involvement (p = 0.008), advanced (III/IV) TNM stage (p < 0.001), and disease recurrence (p < 0.001). Except for lymph node involvement, the association between aggressive histology characteristics at presentation and BRAF-positive PTC also was observed within the age-defined cohorts. In short-term follow-up (mean, 18 months), persistent/recurrent PTC was much more likely to occur in patients who were both BRAF-positive and elderly (22%). CONCLUSIONS: BRAF mutations are equally present in younger and older patients. Aggressive histology characteristics at presentation are associated with BRAF-positive PTC, irrespective of age. However, the well-established association of BRAF with recurrence is limited to older (age ≥65 years) patients.