Thyroid Nodule Samples Research Articles

Genetic testing of thyroid nodules using a gene panel developed on a new generation sequencing platform

Introduction: Twenty-five percent of fine-needle aspiration biopsy samples of thyroid nodules produce indeterminate cytological results. Genetic testing of nodules can contribute to accurate diagnosis. Aim: Developing the first gene panel in Europe utilizing the 23 most relevant thyroid oncogenes with 568 mutations. Method: Examination of the isolated DNA from biopsy samples by Ion Torrent new generation sequencing. Results: The validation of our method was performed on tumor tissue samples, in which 127 genetic variations were identified, yet unknown in thyroid tumors. AXIN1 was the most polymorphic gene, while BRAF c.1799T>A (V600E) was the most frequently identified mutation. We detected 36 clinically relevant variants, 75% of which have not been described in the literature. Six of our 8 cytologically malignant and 8 of our 14 indeterminate as well as 20 of our 28 cytologically benign samples were identified as containing pathologic variants in a driver gene (BRAF c.1799T>A, NRAS c.181C>A). Conclusion: We have developed a validated, reliable new generation sequencing-based method with high positive predictive value (89%) and sensitivity (79%), suitable for the early detection of malignant lesions in the thyroid. Orv Hetil. 2019; 160(36): 1417-1425.

HMGA2 Gene Expression in Fine-needle Aspiration Samples of Thyroid Nodules as a Marker for Preoperative Diagnosis of Thyroid Cancer.

There is a great interest in molecular markers that would help in the preoperative diagnosis of malignant thyroid nodules in cases of indeterminate fine-needle aspiration cytology. The aim of this study was to determine the diagnostic accuracy of HMGA2 gene expression in discriminating benign from malignant thyroid nodules. In this study, 237 preoperative thyroid fine-needle aspiration samples were analyzed prospectively for the expression of the HMGA2 gene by real-time reverse transcription polymerase chain reaction. The results were evaluated against the postoperative histopathologic diagnosis or definitive cytologic diagnosis in cases of nodular goiter and Hashimoto thyroiditis. Among 237 samples from patients with thyroid nodules that were analyzed, 231 were adequate for real-time reverse transcription polymerase chain reaction analysis. With a cutoff value of 8.71 for relative gene expression, HMGA2 was positive in 19 (16.4%) of 116 nodular goiter, 1 (2.6%) of 39 Hashimoto thyroiditis, 9 (28.1%) of 32 follicular adenoma, 0 (0%) of 5 Hurthle cell adenoma, 32 (88.9%) of 36 papillary carcinoma, and 3 (100%) of 3 follicular carcinoma samples. In discriminating between malignant and benign thyroid nodules, HMGA2 has shown specificity of 84.5%, sensitivity of 91.9%, positive predictive value of 53.1%, and negative predictive value of 98.2%. High sensitivity and negative predictive value of HMGA2 for preoperative detection of malignant thyroid nodules shown in this study indicate that it may have a role as an ancillary marker in cytology in the management of patients with thyroid nodules.

Malignancy Rates of Thyroid Cytology: Cyst Fluid Benign or Non-Diagnostic?

BackgroundWe sought to investigate subgroup distribution using Bethesda classification and risks for malignancy. We also compared the malignancy risk of cases that were denoted as non-diagnostic due to cystic contents, with cases that were denoted as non-diagnostic due to presence of other features.Material/MethodsThe study included pathology test results of 1,440 thyroid nodule samples diagnosed using Bethesda classification. Results of 305 thyroidectomy excision specimens from these patients were also compared with cytology results to determine the frequency of malignancy. The non-diagnostic group was divided into two categories: those with cystic contents, and others. Malignancy rates were separately calculated for the two groups, and compared with the other classification groups.ResultsDistribution of malignancy rates by Bethesda classification were as follows: non-diagnostic 12.5% (6/48), benign 1.5% (3/198), atypia of undetermined significance/follicular lesion of undetermined significance (AFLUS) 9% (1/11), suspicious for follicular neoplasm (SFN) 37.5% (3/8), suspicious malignancy 70% (8/26), malignancy 100% (14/14).ConclusionsDespite the limited number of cases, our study concluded that cystic content was closer to the benign category than the non-diagnostic category if the assessment was based on malignancy rates. In this group, similar to aspirations containing plenty of lymphocytes that indicates colloid or lymphocytic thyroiditis, it is still controversial whether criterion for adequacy of follicular epithelial cells should be sought, or if they should be regarded as benign in order to prevent unnecessarily performance of repeat aspirations.

Thyroid Nodules with 2 Prior Inadequate Fine-Needle Aspiration Results: Effect of Increasing the Diameter of the Needle

The major limitation of ultrasound-guided fine-needle aspiration biopsy (US-FNAB) procedures of thyroid nodules are the cytologically nondiagnostic results. The role of increasing the diameter of the needle in the third FNAB (FNAB#3) due to inadequate cytology has as yet not been investigated. The aim of the present study was to evaluate whether increasing the needle diameter could improve the cytologic sampling of thyroid nodules following 2 previous nondiagnostic US-FNAB results. Between July 2012 and December 2012, 140 consecutive patients with 2 prior nondiagnostic US-FNAB results were enrolled in this prospective investigation. Group 22G consisted of 70 patients (78.5% women; mean age, 52 years) having nodules examined with a 22-gauge (G) needle. Group 27G consisted of 70 patients (75.7% women; mean age, 53 years) having nodules examined with a 27-G needle. The rate of nondiagnostic FNAB results was 42.8% (30 of 70) in group 22G and 64.3% (45 of 70) in group 27G, which was a significant difference (P = .011). The large-bore (22 G) needle was found to be statistically significantly superior compared with the small-bore (27 G) needle in diagnostic ability for predominantly solid (P = .014), irregular (P = .013), and halo-free (P = .021) nodules. The accuracy rate was 64.6 and 38% for large-bore (22 G) and small-bore (27 G) needles, respectively. The results of our study showed that increasing the needle lumen diameter significantly improves diagnostic performance in terms of adequate aspirated material and diagnostic accuracy rate following 2 prior nondiagnostic US-FNABs.

Diagnostic Accuracy of Galectin‐3 for Well‐Differentiated Thyroid Cancer on Fine‐Needle Aspiration: A Meta‐analysis

Objectives: (1) Examine and meta-analyze the literature on galectin-3 staining on fine-needle aspiration (FNA) samples of thyroid nodules. (2) Summarize the diagnostic test accuracy of galectin-3 staining on FNA for well-differentiated thyroid cancer (WDTC). Methods: A systematic review of studies from 1990 to 2014 examining the diagnostic test properties of galectin-3 on thyroid nodule samples obtained by FNA with regard to WDTC. Data were meta-analyzed using DerSimonian-Laird random effect models for data pooling. Studies were weighted by inverse variance, and between-study variance was estimated using the Empirical Bayes method. Study heterogeneity and threshold effects were analyzed using the Cochrane Q and Spearman correlation coefficient, respectively. Results: Sixteen studies with 2076 cases were identified. The pooled sensitivity of galectin-3 for WDTC was 89.4% [confidence interval (CI): 87.2-91.4], and specificity was 91.9% (CI: 90.2-93.4). The positive likelihood ratio was 10.05 (CI: 8.24-12.26), and negative likelihood ratio was 0.12 (CI: 0.10-0.15). The diagnostic odds ratio of a positive galectin-3 stain on FNA was 71.3 (CI: 52.7-96.5). The area under the curve for the summary receiver operating characteristics curve (SROC) was 95.3% (standard error: 0.5%). Conclusions: The current study shows galectin-3 staining of preoperative thyroid nodule FNA samples to be a test with strong diagnostic accuracy for WDTC, as seen by its favorable sensitivity, specificity, diagnostic odds ratio, and SROC curve. This supports its role as a useful adjunct in the preoperative workup of thyroid nodules.

Galectin‐3 as Adjunct to HBME‐1 Staining of Fine‐Needle Aspiration Biopsy Samples of Thyroid Nodules

Objectives: (1) Examine the added value of galectin-3 to HBME-1 staining on fine-needle aspiration (FNA) of thyroid nodules. (2) Correlate galectin-3 on FNA with pathology results both on FNA and final surgical pathology. Methods: A retrospective review of the charts of 53 patients undergoing FNA at the Jewish General Hospital in Montreal, Canada, in 2013 for the investigation of thyroid nodules whose FNA samples underwent HBME-1 and galectin-3 staining in addition to pathological examination. Results: Of 53 FNABs, 20 (37%) were galectin-3 positive, 24 (45%) were galectin-3 negative, and 9 (17%) were equivocal. With regard to HBME-1, 15 (28%) samples were positive, 32 (60%) were negative, and 6 (11%) were equivocal. Both stains correlated strongly with each other ( P < .001) as well as with pathologist examinations of the FNA samples ( P < .001 for both galectin-3 and HBME-1). Eleven patients underwent total or partial thyroidectomy. In correlation with surgical pathology, galectin-3 was correctly positive in 5 patients, correctly negative once, falsely positive once, falsely negative once, and indeterminate in 3 patients. HBME-1 was correctly positive in 7 patients, correctly negative in 2 patients, falsely negative once, indeterminate once, and without false positives. When combining HBME-1 and galectin-3, 8 true positives, 1 true negative, and 1 false positive were observed. No false negatives were found when combining both stains. Conclusions: Galectin-3 may be a useful adjunct to HBME-1 staining in FNA of thyroid nodules in order to detect papillary thyroid carcinoma. Further research is needed to confirm these results.

Comparison of fine‐needle aspiration and fine‐needle capillary sampling of thyroid nodules: A prospective study with emphasis on the influence of nodule size

The objective of this study was to compare the sampling efficiency of ultrasound-guided fine-needle aspiration (FNA) and fine-needle capillary (FNC) sampling in thyroid nodules, in which the authors specifically analyzed the influence of nodule size. This study included 280 thyroid nodules in 275 consecutive patients. The nodules were divided into 4 size subgroups: ≤5.0 mm, from 5.1 to 10.0 mm, from 10.1 to 20.0 mm, and >20.0 mm. Each nodule was sampled by both FNA and FNC. The final cytopathologic findings were reported. The smears were scored and then categorized as diagnostically inadequate, adequate, or superior on the basis of 4 parameters, which included background clot or blood, the number of obtained cells, preserved tissue architecture, and cellular degeneration. The κ scores for agreement of the cytopathologic results between FNA and FNC sampling in the 4 size subgroups were 0.377, 0.455, 0.751, and 0.352 for nodules that measured ≤5.0 mm, from 5.1 to 10.0 mm, from 10.1 to 20.0 mm, and >20.0 mm, respectively. The proportion of nondiagnostic of FNAs was significantly lower than the proportion of nondiagnostic FNC samples in nodules that measured >20.0 mm (P = .037). Scores for the 4 diagnostic parameters were significantly greater in FNAs than in FNC samples in nodules that measured from 5.1 to 10.0 mm and >20.0 mm (all P < .05); however, similar results were not observed in the nodules that measured ≤5.0 mm or from 10.1 to 20.0 mm (all P > .05). Also, FNA yielded significantly more diagnostically superior specimens than FNC sampling in nodules that measured from 5.1 to 10.0 mm and >20.0 mm (P < .05 for both). The current findings indicated that FNA may be more suitable than FNC for sampling nodules that measure from 5.1 to 10.0 mm and >20.0 mm; whereas, for nodules that measure ≤5.0 mm and from 10.1 to 20.0 mm, the 2 techniques could yield specimens with similar quality.

Impact of Molecular Screening for Point Mutations and Rearrangements in Routine Air-Dried Fine-Needle Aspiration Samples of Thyroid Nodules

The diagnostic limitations of thyroid fine-needle aspiration (FNA), such as the indeterminate category, can be partially overcome by molecular analyses. However, until now, rearrangements have only been detected in fresh FNA material and the number of follicular thyroid carcinomas (FTCs) was rather low in previous studies. We aimed at investigating the impact of point mutations and rearrangement detection in a set of routine air-dried FNA smears with a higher percentage of FTCs. RNA and DNA was extracted from 310 FNAs (164 indeterminate, 57 malignant, 89 benign) and corresponding formalin-fixed paraffin-embedded tissue (156 follicular adenomas [FAs], 32 FTCs, 44 papillary thyroid carcinomas [PTCs], 9 follicular variant PTCs, and 69 goiters). PAX8/PPARG and RET/PTC rearrangements were detected by qPCR, BRAF and RAS mutations by high-resolution melting PCR and by pyrosequencing. Forty-seven mutations were detected in the FNAs: 22 BRAF, 13 NRAS, and 3 HRAS mutations, 8 PAX8/PPARG, and one RET/PTC-rearrangement. While the presence of a BRAF and RET/PTC mutation was associated with cancer in 100% of samples each, the presence of a RAS and PAX8/PPARG mutation was associated with cancer in only 12% and 50% of samples, respectively. In the indeterminate group 4 of 25 carcinomas were identified by molecular FNA screening, which increased the sensitivity from 67% (cytology alone) to 75% (cytology plus molecular screening). Molecular screening for point mutations and rearrangements is feasible in air-dried FNAs. Although the impact of detecting point mutations and rearrangements in FNAs has most likely been overestimated in previous studies, molecular FNA analyses improve presurgical diagnostics. The detection of BRAF mutations in FNA may improve the choice of surgery and postsurgical treatment. Further data are necessary to elucidate the true impact of detecting RAS and PAX8/PPARG mutations in FNAs. The inclusion of additional rare somatic mutations and miRNA markers might further improve the impact of molecular FNA diagnostics.

A gene expression signature that distinguishes malignant from benign thyroid nodules.

e21011 Background: Thyroid nodules can be detected in as high as 67% of the population. Distinguishing thyroid cancers from benign lesions is crucial for determining an appropriate treatment plan. For years a gene expression signature for discriminating malignant from benign thyroid nodules has been sought by clinicians. In this study, multivariate bioinformatics tools were used to generate a qPCR based gene expression signature for determining malignancy in thyroid nodules. Methods: Multiple mathematical models, such as Random Forest, Support Vector Machine (SVM), and Nearest Shrunken Centroid (NSC), were used to analyze published microarray data sets and select 366 putative classifier (biomarker) mRNA targets. The selected 366 genes were further evaluated for their expression pattern by real-time PCR using a panel of 49 pathology assessed thyroid nodule samples (fresh frozen, 23 malignant and 26 benign). Results: Using the qPCR data set, Random Forest was compared with SVM and NSC classifier methods and was found to be more successful in finding genes with better discriminative powers. A Random Forest method identified a panel of 7 genes together with 5 reference genes as a gene expression signature for thyroid malignancy, which led to the development of a companion classifying algorithm to provide a probability score to assess malignancy of thyroid nodules. In our limited sample set, this signature was shown to distinguish malignant and benign thyroid nodules with 92% accuracy and 100% specificity. Conclusions: Our results suggest that a combination of multiple bioinformatics analysis tools is the proper approach for biomarker candidate selection from high-throughput gene expression data. As demonstrated here, panel of 12 genes and a companion classification algorithm has the potential to successfully discriminate malignant thyroid nodule with high accuracy and specificity. This panel of twelve genes is for molecular biology applications only.

Pyrosequencing cut‐off value identifying BRAFV600E mutation in fine needle aspiration samples of thyroid nodules

Recently, tremendous efforts have been made towards the development of sensitive techniques to detect the BRAF(V600E) mutation in fine needle aspiration biopsy (FNAB) samples. However, newly developed quantitative and semi-quantitative methods, such as dual-priming oligonucleotide (DPO)-based multiplex polymerase chain reaction (PCR), have the potential to generate false-positive (FP) results. To eliminate the possibility of FP results, we generated a receiver operating characteristic (ROC) curve to investigate the diagnostic accuracy of pyrosequencing using quantitative data. Cytological diagnoses of 983 thyroid nodules were made according to the Bethesda System 2007. The BRAF(V600E) mutation was analysed by pyrosequencing, and statistical analyses were performed. Of the 983 nodules, 902 were adopted to evaluate the diagnostic value of pyrosequencing. The number of pathologically confirmed malignancies was 192, of which 182 were papillary thyroid cancer (PTC). By generating an ROC curve, we defined the optimal cut-off value of the mutant allele peak as 5·95% (area under the curve, 0·849; sensitivity, 0·55; 1-specificity, 0). When we applied this selective cut-off value, the number of PTCs positive for BRAF(V600E) was 99 (54·4% of the total number of PTCs). With cytology alone, the diagnostic sensitivity and specificity of detecting malignancy were 71·2% and 100%, respectively. Pyrosequencing improved the diagnostic sensitivity from 71·2% to 78·5% (McNemar's test, P < 0·001), without any change in the diagnostic specificity. When 'suspicious for malignancy' was considered a positive cytological outcome, pyrosequencing increased the diagnostic sensitivity of cytology from 95·8% to 96·9%; however, this improvement did not show statistical significance (McNemar's test, P > 0·05). Pyrosequencing is an effective method for detecting the BRAF(V600E) mutation in FNAB samples. By allowing the optimal cut-off value to be determined, pyrosequencing improves the diagnostic sensitivity while eliminating the possibility of FP results.

Ultrasonography‐guided fine‐needle aspiration cytology for thyroid nodules: An emphasis on one‐sampling and biopsy techniques

The aim of this study was to assess the adequacy and efficacy of ultrasonography (US)-guided fine-needle aspiration cytology (US-FNAC) with one-sampling technique (only one specimen through a single needle pass was obtained during the procedure on each thyroid nodule in each study patient) for the cytological diagnosis of thyroid nodules. In this study, US-FNAC techniques, including "free two-hand," "mixed sampling," "flipping-extraction," and "single-needle-pass" procedures were used to collect thyroid cells from July 2007 to June 2009. The cytopathology results and patients' complications were reviewed retrospectively. Of the 1456 thyroid-nodule samples obtained from 977 patients (1.49 per patient), the incidence of adequate and inadequate samplings was 88.5% (1289/1456) and 11.5% (167/1456), respectively. After thyroid surgery in 396 patients, 568 nodules were confirmed as 353 papillary thyroid carcinomas including one diffuse sclerosing variant, five follicular thyroid carcinomas, three medullary thyroid carcinomas, one anaplastic thyroid carcinoma, one metastatic renal cell carcinoma, two poorly differentiated carcinomas, 17 follicular adenomas, two nodular thyroiditis, two pseudonodules related to thyroiditis, and 182 cases of nodular hyperplasia. Sensitivity, specificity, positive predictive value, negative predictive value, accuracy, false-negative rate, and false-positive rate for the US-FNAC were 94.3%, 91.9%, 96.2%, 88.3%, 93.6%, 3.9%, and 2.6%, respectively. There were no significant patients' complications, but 87 patients (8.9%) reported mild pain during or after the procedure. This study showed a good adequacy and efficacy of US-FNAC for thyroid nodules despite one-sampling.

A Comparison Of Fine-Needle Aspiration Versus Non-Aspiration Cytology Of Thyroid Nodules

Background Fine needle aspiration (FNA) is considered the investigation of choice in cytological sampling of thyroid nodules. Non-aspiration fine needle cytology (NAC) has been described as an alternative method with technical and interpretive advantages. This study compares the sampling adequacy and diagnostic accuracy of NAC with FNA in predicting neoplasia and malignancy in thyroid nodules. Methods Patients presenting to a single surgeon with a thyroid nodule had both NAC and FNA performed. Both NAC and FNA specimens of all those who had subsequent thyroid resection were retrospectively graded and correlated with the histological diagnosis to determine rates of adequacy and diagnostic accuracy. Results Both NAC and FNA plus surgical resection were performed on 65 thyroid nodules. NAC produced less inadequate specimens (26%) than FNA (37%). Combining both techniques reduced the inadequacy rate to 20%. In predicting malignancy, FNA and NAC were equally sensitive (89%) but FNA had higher specificity (66 v 54%) and accuracy (71 v 60%). In predicting neoplasia, FNA again had higher specificity (90 v 77%) and accuracy (85 v 79%) but sensitivity rates were similar (81 v 81%). Conclusion NAC is a technically simple method of sampling thyroid nodules and appears to produce more adequate specimens. It has similar sensitivity to FNA in predicting neoplasia and therefore surgery. However, FNA appears to have better overall accuracy. In order to maximise yield it may be appropriate to use both sampling methods in the cytological investigation of thyroid nodules.

Preparation of thyroid FNA material for routine cytology and BRAF testing: A validation study

V600E BRAF mutation is emerging as an independent marker of papillary thyroid carcinoma aggressive behavior. Papillary thyroid carcinomas harboring this mutation should be extensively resected. However, this requires an unquestionable cytological diagnosis of malignancy. Thus, cytological specimens should be properly handled to provide both morphological and molecular information. Here, we assessed whether our method of preparation of fine-needle aspiration material is suitable for both tests. A series of 128, routinely performed, fine-needle aspirations was analyzed. Each nodule was punctured three times. A representative Diff-Quik smear prepared from the first two passages was evaluated onsite. When microscopy was diagnostic (n = 44), the third needle pass was dedicated to harvest material for BRAF testing; in the remaining cases (n = 84), additional direct smears for cytology were prepared and the remaining material in the needle plus the needle rinsing was collected for BRAF testing. Cellularity was adequate in 126/128 (98%) cases. Cytological diagnoses were inadequate (2%), benign (85%), follicular lesion of undetermined significance (5%), follicular neoplasms (2%), suspicious for malignancy (2%), and malignant (4%). Higher average of extracted DNA concentration was observed in the dedicated pass group (25.9 vs 7.95 ng/microl). However, the rate of successful exon 15 BRAF amplification was similar with (43/44; 97.7%) or without (79/84; 94%) the dedicated pass. Thus, our protocol is suitable for both tests. Whenever necessary BRAF testing may also be performed on the residual samples of thyroid nodules, without interfering with routine cytology.

Dual priming oligonucleotide–based multiplex PCR analysis for detection of BRAFV600E mutation in FNAB samples of thyroid nodules in BRAFV600E mutation–prevalent area

To evaluate the diagnostic value of dual priming oligonucleotide (DPO)-based multiplex polymerase chain reaction (PCR) for the detection of BRAF(V600E) mutations in ultrasound-guided fine-needle aspiration biopsy (US-FNAB) of thyroid nodules. Our institutional review board approved this retrospective study, and informed consent was not required from patients. The 130 patients underwent US-FNAB to evaluate BRAF status in thyroid nodules. In FNAB washouts, DPO-based multiplex PCR, direct DNA sequencing, and PCR-restriction fragment length polymorphism (RFLP) were used to detect BRAF(V600E). The diagnostic performance of these methods was calculated. We compared cytologic results by BRAF status. Diagnostic accuracy and sensitivity were highest when screening with DPO-based multiplex PCR. BRAF(V600E) positivity was a useful marker at thyroid nodules with "suspicious for papillary thyroid carcinoma" or "inadequate" cytological result. DPO-based multiplex PCR may be an alternative to direct DNA sequencing because of its high sensitivity, high accuracy, and simplicity. BRAF(V600E) may be a useful additional diagnostic marker in BRAF(V600E)-prevalent areas.

Molecular Testing for Mutations in Improving the Fine-Needle Aspiration Diagnosis of Thyroid Nodules

Thyroid nodules are common in adults, but only a small fraction of them are malignant. Fine-needle aspiration (FNA) with cytological evaluation is the most reliable tool for cancer diagnosis in thyroid nodules. However, 10-40% of nodules are diagnosed as indeterminate by cytology, making it difficult to optimally manage these patients. The aim of this study was to establish the feasibility and role of testing for tumor-specific mutations in improving the FNA diagnosis of thyroid nodules. The prospective study included 470 FNA samples of thyroid nodules from 328 patients. At the time of aspiration, a small portion of the material was collected and tested for BRAF, RAS, RET/PTC, and PAX8/PPARgamma mutations. The mutational status was correlated with cytology and either surgical pathology diagnosis or follow-up (mean, 34 months). A sufficient amount of nucleic acids were isolated in 98% of samples. Thirty-two mutations were found, including 18 BRAF, eight RAS, five RET/PTC, and one PAX8/PPARgamma. The presence of any mutation was a strong indicator of cancer because 31 (97%) of mutation-positive nodules had a malignant diagnosis after surgery. A combination of cytology and molecular testing showed significant improvement in the diagnostic accuracy and allowed better prediction of malignancy in the nodules with indeterminate cytology. These results indicate that molecular testing of thyroid nodules for a panel of mutations can be effectively performed in a clinical setting. It enhances the accuracy of FNA cytology and is of particular value for thyroid nodules with indeterminate cytology.

Thyroid fine-needle aspiration samples inadequate for reverse transcriptase-polymerase chain reaction analysis

Analysis of different tumor markers by reverse transcriptase-polymerase chain reaction (RT-PCR) in fine-needle aspiration samples of thyroid nodules has been studied with the objective of improving the accuracy of the preoperative diagnosis of thyroid lesions. The aim of the current study was to investigate thyroid fine-needle aspiration samples inadequate for RT-PCR analysis and to determine whether there is a correlation between their proportion and the method of sampling used or the greatest dimension of the nodules. A total of 350 fine-needle aspiration samples from patients with thyroid nodules were analyzed. After the aspirate was smeared for conventional cytology, the leftover material in the needle was used for RT-PCR analysis in 1 group of 175 patients. In another group of 175 patients, a separate puncture was performed to obtain material for RT-PCR analysis only. Samples were considered adequate for RT-PCR analysis if the expression of both glyceraldehyde-3-phosphate dehydrogenase and thyroglobulin was found by RT-PCR. In total, 61 (17.4%) samples inadequate for RT-PCR were detected. All 12 samples that were inadequate for cytologic diagnosis were also found to be inadequate for RT-PCR analysis. The proportion of inadequate samples for RT-PCR was found to be significantly higher in samples taken from leftover material in the needle (21.7%) then in samples from a separate puncture (13.1%) (P = .049). No statistically significant correlation between the adequacy of samples for RT-PCR and the largest dimension of the nodule was found. The proportion of samples inadequate for RT-PCR was found to be higher in samples taken from leftover material in the needle than in samples obtained from a separate puncture.

Elastic Moduli of Thyroid Tissues under Compression

The aim of this study was to evaluate the elastic moduli of thyroid tissues under uniaxial compression and to establish the biomechanical fundamentals for accurate interpretation of thyroid elastograms. A total of 67 thyroid samples (24 samples of normal thyroid tissue, 2 samples of thyroid tissue with chronic thyroiditis, 12 samples of adenomatous goiter lesions and 7 samples of follicular adenoma, 19 samples of papillary adenocarcinoma (PAC) and 3 samples of follicular adenocarcinoma (FAC)) obtained from 36 patients who had received thyroid surgery were subjected to biomechanical testing within three hours after surgical resection at precompression strains of 5%, 10% and 20% and applied strains of 1%, 2%, 5% and 10% of sample height. As a result, the mean values of elastic moduli for benign thyroid lesions at all examined precompression levels were significantly higher than those for normal thyroid tissue measured at the same load (p<0.01). At low precompression (5%) and compression (1-2%) levels, benign thyroid nodule samples were 1.7 times harder than normal thyroid tissue. At high precompression (20%) and compression (10%) levels, this difference increased to 2.4 times. Stiffness of PAC samples was significantly higher than those for normal thyroid tissue and benign thyroid tumors measured at the same load (p<0.01). At low precompression (5%) and compression (1-2%) levels, PAC samples were 5.0 times harder than normal thyroid tissue. At high precompression (20%) and compression (10%) levels, this difference increased to 17.7 times. In contrast, samples of FAC were much softer than PAC (p<0.05) and were comparable in stiffness to normal thyroid tissues. The significant differences in the stiffness between normal thyroid tissue and thyroid tumors may provide useful information for accurate interpretation of thyroid elastograms.

Cyclooxygenase-2 expression in thyroid nodules.

Factors contributing to the development of thyroid neoplasia remain poorly understood. Recent evidence indicates that overexpression of the inducible cyclooxygenase, COX-2, is important in the pathogenesis of epithelial carcinomas. These studies were undertaken to evaluate whether COX-2 is up-regulated in human thyroid neoplasia. Benign (n = 14), and malignant (n = 14) thyroid nodules were analyzed for expression of COX-2 mRNA by quantitative RT-PCR. Immunoblotting and immunohistochemistry were performed on representative samples. Three human thyroid cancer cell lines were similarly analyzed for COX-2 expression. Levels of COX-2 mRNA were significantly increased in thyroid nodule samples compared with adjacent thyroid tissue in the malignant specimens but not in the benign specimens. Additionally, COX-2 mRNA levels were significantly increased in malignant nodule samples compared with benign nodule samples. COX-2 protein expression was higher in 8 of 10 thyroid nodules compared with the adjacent tissue. Immunohistochemical analysis localized expression of COX-2 to the malignant epithelial cells. Immunofluorescence demonstrated COX-2 protein expression in all three thyroid cell lines. Finally, COX-2 expression could be detected by RT-PCR in fine needle aspiration specimens of thyroid nodules. These data indicate that COX-2 is up-regulated in human thyroid cancer, but not in benign thyroid nodules, and suggest that COX-2 expression may serve as a marker of malignancy in thyroid nodules.