Concomitant high expression of survivin and vascular endothelial growth factor-C is strongly associated with metastatic status of lymph nodes in papillary thyroid carcinoma.

PURPOSE: Papillary thyroid carcinoma (PTC) has a strong propensity to metastasize to regional lymph nodes which increases the risk of local-regional relapse and affects the course of the disease. Molecular pathogenesis of lymph node metastasis (LNM) is not yet fully understood. Survivin, a multifunctionale molecule involved in apoptosis, proliferation and angiogenesis, and vascular endothelial growth factor-C (VEGF-C) are suggested to be implicated in lymphatic metastases of human malignancies. MATERIALS AND METHODS: Expression of survivin and VEGF-C was examined by immunohistochemistry and Western blot in 75 cases of PTCs in relation to their LNM status. Additionally, survivin and VEGF-C were immunohistochemically analyzed in 15 primary PTCs paired with their metastatic tissue in lymph nodes. RESULTS: High expression of survivin and VEGF-C was found in 62.7% and 64.0% cases, respectively, with a positive correlation to each other (Spearman's correlation co-efficient = 0.878, P < 0.001). Expression levels of both proteins were significantly higher in patients with LNM than in those without LNM (P < 0.001). The rate of concomitant high expression of survivin and VEGF-C in patients with LNM involvement was 88.9% (P < 0.01). Metastatic tissue in lymph nodes expressed survivin and VEGF-C at the same high extent as their primary tumors. CONCLUSION: Concomitant high expression of survivin and VEGF-C is closely associated with LNM status of PTC patients, which suggests their cooperation in the metastatic process. Evaluation of survivin and VEGF-C expression could be clinically significant in predicting the metastatic potential of PTC and subsequent treatment and follow-up of these patients.

Malignant risk stratification of thyroid FNA specimens with indeterminate cytology based on molecular testing.

BACKGROUND: Fine-needle aspiration (FNA) has been employed for many years for examining thyroid nodules, and the cytology of aspirates is the primary determinant for whether thyroidectomy is indicated. Fifteen to thirty percent of thyroid nodules, not being clearly benign or malignant, fall into an indeterminate category. The main goals of molecular diagnostics for thyroid nodules are to prevent unnecessary surgery in patients with benign nodules and to stop patients with malignant nodules from being subjected to repeated operations. METHODS: This study was designed to evaluate the diagnostic utility of 4 markers in thyroid FNA cytology via testing for the BRAF V600E mutation and the expression of microRNA-221, microRNA-222, and galectin-3 protein in FNA samples with indeterminate cytology. RESULTS: A predictor model distinguishing benign samples from malignant samples on the basis of the 4 aforementioned markers was formulated. This decision model provided a sensitivity of 73.5%, a specificity of 89.8%, and a diagnostic accuracy of 75.7%. The positive predictive value was 80.6%, and the negative predictive value was 85.5%; this suggested that the prediction had good reliability. CONCLUSIONS: One hundred twenty FNA samples were examined, and 62 nodules were classified as benign with the proposed diagnostic algorithm. This resulted in a reduction of the initial 120 patients to 58 and thus decreased by half the number of persons undergoing surgery.

Strong expression of HBME-1 associates with high-risk clinicopathological factors of papillary thyroid carcinoma.

Thyroid cancer comprises a heterogeneous group of lesions with great diversity of biological behaviour. Markers which could help clinicians to identify high-risk patients for tailored optimization of clinical management are of crucial importance. HBME-1 protein level was analysed immunohistochemically using routinely prepared archival tissue sections of a broad range of papillary thyroid carcinoma (PTC) variants and in corresponding lymph node metastases (LNM). The results were evaluated in comparison with clinicopathological features of PTC. Positive immunoreaction was noticed in most classical (83/92; 90.2 %), follicular (60/71; 84.5 %) and trabecular (4/5; 80.0 %) variants of PTC. All cases of macrofollicular, Warthin-like and diffuse sclerosing PTC variants were HBME-1 positive (4/4, 3/3, 2/2; 100 % respectively). Tall cell and solid PTC variants showed diversity of staining (2/3; 66.67 % and 13/23; 56.52 % respectively), while PTCs with mixed histological pattern containing insular areas were mainly weakly positive (2/5; 40.0 %). A single case of clear cell PTC variant showed no reaction. Moreover, all matched metastatic PTC into lymph nodes (LNM) were HBME-1 positive (17/17; 100 %) and expressed HBME-1 in a similar pattern to the matched primary tumour. We also found a statistically significant association between high HBME-1 expression and the presence of lymph node metastasis, advanced pT status and pTNM stage (P < 0.05), but only a tendency for association with extrathyroidal invasion of the tumour (P = 0.058). Therefore, we recommend using immunoexpression of HBME-1 as useful mean to increase the likelihood of detecting most PTC variants and to predict some unfavourable clinical parameters in these patients.

Changes in the expression pattern of apoptotic molecules (galectin-3, Bcl-2, Bax, survivin) during progression of thyroid malignancy and their clinical significance.

BACKGROUND: Papillary carcinoma of the thyroid (PTC) is generally a slow growing tumor with favorable prognosis, while anaplastic thyroid carcinoma (ATC) is highly aggressive malignancy. Genetic defects in apoptotic pathways may contribute to differences in their biological behavior. METHODS: In this study, we analyzed immunohistochemically the expression of apoptosis-related molecules: galectin-3, Bcl-2, survivin (antiapoptotic), and Bax (pro-apoptotic), in archival tissue sections of PTC (n = 69) and ATC (n = 30) and correlated the results with clinicopathological parameters of these tumors. RESULTS: Galectin-3 and Bcl-2 showed a similar trend of down-regulation from high levels of both in PTC to low levels in ATC (p < 0.05). Bax was expressed at high levels in both type of thyroid carcinoma. Expression of survivin increased from PTC to ATC (p < 0.05), which may, at least in part, further facilitate the ability of malignant thyroid cell of ATC to escape programmed cell death despite high Bax expression. Only survivin, but not galectin-3, Bcl-2, or Bax, correlated significantly with lymph node metastasis presence and advanced stages of malignancy. CONCLUSIONS: In conclusion, this study documented down-regulation of galectin-3 and Bcl-2 (antiapoptotic molecules) and stepwise increase of survivin (inhibitor of apoptosis), during thyroid tumor progression from PTC to ATC. Correlation of high survivin expression with aggressive behavior implies its role in progression of thyroid tumor malignancy and suggests that survivin could be a useful tool in the prediction of aggressiveness of a subset of papillary carcinomas and a possible target for molecular therapy for ATC patients.

Morphological and functional changes in pituitary-thyroid axis following prolonged exposure of female rats to constant light.

Light regulates numerous physiological functions and synchronizes them with the environment, in part by adjusting secretion of different hormones. We hypothesized that constant light (CL) would disturb pituitary-thyroid axis. Our aim was to determine morphological and functional changes in this endocrine system in such extreme conditions and, based on the obtained results, to propose the underlying mechanism(s). Starting from the thirtieth postnatal day, female Wistar rats were exposed to CL (600 lx) for the following 95 days. The controls were maintained under the regular laboratory lighting conditions. After decapitation, pituitaries and thyroids were prepared for further histomorphometric, immunohistochemical, and immunofluorescence examinations. Concentration of thyroid stimulating hormone (TSH), total T4 and T3 (TH) were determined. Thyroid tissue of light-treated rats was characterized by microfollicular structure. We detected no change in total thyroid volume, localization and accumulation of thyroglobulin, thyroid peroxidase, and sodium-iodide symporter in the follicular epithelium of CL rats. The volume of follicular epithelium and activation index were increased, while volume of the colloid and serum levels of TH decreased. In the pituitary, the relative intensity of TSH ß-immunofluorescence signal within the cytoplasm of thyrotrophs increased, but their average cell volume and the relative volume density decreased. Serum TSH was unaltered. We conclude that exposure of female rats to CL induced alterations in pituitary-thyroid axis. Thyroid tissue was characterized by microfollicular structure. Serum TH levels were reduced without accompanying increase in serum TSH. We hypothesize that increased secretion and clearance of TH together with unchanged or even decreased hormonal synthesis, resulted in decreased serum TH levels in CL group. We assume this decrease consequently led to increased synthesis and/or accumulation of pituitary TSH. However, decreased average TSH cell volume and relative volume density, together with unchanged serum TSH, point to additional, negative regulation of thyrotrophs.

Enhanced activation of matrix metalloproteinase-9 correlates with the degree of papillary thyroid carcinoma infiltration.

AIM: To determine whether matrix metalloproteinase-9 (MMP-9) may be a useful adjunctive tool for predicting unfavorable biological behavior of papillary thyroid carcinoma (PTC) by evaluating the expression profile and proteolytic activity of MMP-9 in PTC by different techniques and correlating the findings with clinicopathological prognostic factors. METHODS: Immunohistochemical localization of MMP-9 was analyzed with antibodies specific for either total or active MMP-9. Activation ratios of MMP-9 were calculated by quantifying gel zymography bands. Enzymatic activity of MMP-9 was localized by in situ zymography after inhibiting MMP-2 activity. RESULTS: Immunostaining of total and active MMP-9 was observed in tumor tissue and occasionally in non-neoplastic epithelium. Only active MMP-9 was significantly associated with extrathyroid invasion, lymph-node metastasis, and the degree of tumor infiltration (P<0.001, P=0.004, and P<0.001, respectively). Gelatin zymography revealed a correlation between the MMP-9 activation ratio and nodal involvement, extrathyroid invasion, and the degree of tumor infiltration. In situ zymography showed that gelatinases exerted their activity in tumor parenchymal and stromal cells. Moreover, after application of MMP-2 inhibitor, the remaining gelatinase activity, corresponding to MMP-9, was highest in cancers with the most advanced degree of tumor infiltration. CONCLUSIONS: This is the first report suggesting that the evaluation of active MMP-9 by immunohistochemistry and determination of its activation ratio by gelatin zymography may be a useful adjunct to the known clinicopathological factors in predicting tumor behavior. Most important, in situ zimography with an MMP-2 inhibitor for the first time demonstrated a strong impact of MMP-9 activity on the degree of tumor infiltration during PTC progression.

Caveolin-1 expression in papillary thyroid carcinoma: correlation with clinicopathological parameters and BRAF mutation status.

OBJECTIVE: We aimed to investigate the role of caveolin-1 in papillary thyroid carcinoma pathogenesis. STUDY DESIGN: Case series with chart review. SETTING: Institute for the Application of Nuclear Energy. SUBJECTS AND METHODS: We evaluated the expression of caveolin-1 in papillary thyroid carcinoma (PTC) by Western blot (WB) and compared the findings with immunohistochemical (IHC) expression of both epithelial and stromal caveolin-1 on the corresponding histological specimens. The results were related to clinicopathological features and BRAF mutation status. RESULTS: Caveolin-1 expression was found in malignant thyroid epithelium and more abundantly in tumor stroma but varied in both compartments within and between PTC subtypes. Caveolin-1 expression in the epithelium was more intense in classical PTC than in the other histological types. On the contrary, stromal caveolin-1 expression was stronger in the follicular, solid, and trabecular PTC variants than in classical PTC. Trends for down-regulation of caveolin-1 expression in epithelium and up-regulation in stroma from the classical via follicular to the solid variant were observed. The relation of WB and IHC results with clinicopathological parameters showed lower caveolin-1 tissue content in BRAF mutated tumors (P < .05), a positive correlation of epithelial caveolin-1 expression with lymph node metastasis (P < .05), and a negative association of stromal caveolin-1 expression with the degree of neoplastic infiltration and BRAF status. CONCLUSION: Altered expression of caveolin-1 in the thyroid epithelial and stromal compartments may be involved in the pathogenesis of PTC. The potential clinical significance of caveolin-1 expression, as well as its relation to BRAF mutation status, deserves further investigation.

Evaluation of survivin expression and its prognostic value in papillary thyroid carcinoma.

Overexpression of survivin, an inhibitor of apoptosis protein, has been found in a variety of human cancers, and is associated with tumor aggressiveness. In this study, we analyzed the expression of survivin in papillary thyroid carcinoma (PTC) and evaluated its clinical significance for predicting an aggressive course of disease at the time of diagnosis. Survivin expression was determined by immunohistochemistry in 104 tissue specimens of PTC, confirmed by Western blot and correlated with clinicopathological parameters. Of the tumors examined, 74 (71.15%) showed high cytoplasmic survivin expression. There was no association between high survivin expression and age, gender or tumor size. On the other hand, it was closely correlated with the presence of lymph node metastasis (P=0.009), and there was a tendency for correlation with extrathyroidal invasion (P=0.062). The high risk PTC group (TNM stage III-IV) was associated with high levels of survivin (P=0.027). These results indicate that survivin is an unfavorable molecule for PTC prognosis, and that its high expression may indicate a subset of PTC patients with a more aggressive disease course. Evaluation of its expression in fine needle aspiration samples could be a useful tool for the identification of those PTC patients who require more extensive surgery, careful follow-up and therapeutic strategy.

Cytokeratin19 expression discriminates papillary thyroid carcinoma from other thyroid lesions and predicts its aggressive behavior.

Cytokeratin19 (CK19) has been reported as a useful marker of thyroid tumors. We evaluated its value for differential diagnosis of thyroid neoplastic lesions and assessed its usefulness for predicting aggressive behavior of papillary thyroid carcinomas by correlating immunohistochemical results with clinicopathological features of the patients. A total of 351 thyroid tissue samples included 27 follicular adenomas (FTA), 18 follicular carcinomas (FTC), 147 papillary carcinomas (71 of follicular type-PTCfv and 76 of classical type-PTCcl) and 33 cases of anaplastic carcinoma with 126 adjacent thyroid tissues. Diagnostic usefulness of CK19 was determined by ROC analysis, while its value as a predictive marker of PTC was tested by univariate and multivariate analysis. According to ROC analysis, CK19 can discriminate both types of PTC from other neoplasias of the thyroid gland (p < 0.05). Although greatest accuracy was gained for the identification of PTCcl (91.07 %), this marker was also helpful for distinguishing PTCfv from FTA and FTC (accuracy 71.43 and 65.17 %, respectively). Regarding the univariate set of tests, high expression of CK19 correlated significantly with age, multifocality, extrathyroidal extension, pT status and pTNM stage of PTC (p < 0.05 for all). Multivariate analyses confirmed the significant association of high CK19 expression with extrathyroidal extension of PTC as well as with pTNM stage (p < 0.05 and p < 0.01, respectively). CK19 is a useful marker for the identification of both types of PTC. High expression of this protein predicts the aggressive behavior of PTC and can help in the identification of a particular subgroup of PTC patients with a potentially worse prognosis.

Caveolin-1 expression in thyroid neoplasia spectrum: comparison of two commercial antibodies.

We evaluated caveolin-1 expression in the human thyroid neoplasia spectrum with the aim of examining differences in expression as detected by two anti-caveolin-1 antibodies, and secondly, to investigate the association of caveolin-1 expression levels with aggressive papillary thyroid carcinoma (PTC). Immunohistochemical staining using sc894 or AV09019 antibodies revealed that caveolin-1 was generally overexpressed in the PTC group as a whole (classical and follicular variant) when compared to peritumoral tissue (PT), while it was not detected in about half of follicular thyroid carcinoma (FTC) and majority of follicular adenomas (FTA). Caveolin-1 expression decreased in the following order: clPTC, fvPTC, FTC, PT and FTA. The diagnostic accuracy of AV09019 was better than that of sc894 for discriminating: FTA from FTC, FTA or FTC from the follicular variant of PTC, total PTC from nonmalignant tissue, and malignant tumors from nonmalignant tissue. Spearman's analysis revealed positive correlations of caveolin-1 expression and extrathyroidal invasion (p< 0.05) in PTC for both antibodies. Additionally, AV09019 antibody correlated caveolin-1 upregulation with pathological T status. To conclude, as an immunohistochemical marker AV09019 antibody performed better than sc894 in distinguishing certain histotypes of thyroid tumors. In addition, increased expression of caveolin-1 may be considered as an indicator of papillary carcinoma progression.

Matrix metalloproteinase-9 and the Cu/Zn ratio as ancillary diagnostic tools in distinguishing between the classical and follicular variants of papillary thyroid carcinoma.

The most common histological variants of papillary thyroid carcinoma (PTC), classical (CPTC) and follicular (FPTC), have different diagnostic features, molecular biology, and prognosis. Matrix metalloproteinase-9 (MMP-9) endopeptidase which degrades the components of the extracellular matrix is essential in the invasive growth and metastasizing of malignant tumors. The serum copper (Cu)/zinc (Zn) ratios are sensitive diagnostic and prognostic indicators in oncology since Cu- and Zn-dependent enzymes play important roles in the genesis and the progression of tumors. The aim of this study was to examine the expressions of MMP-9 in tissues of CPTC and FPTC, as well as to determine the Cu/Zn ratios in the same samples. MMP-9 was determined immunohistochemically, and the concentrations of copper and zinc in thyroid tissue were determined by means of flame atomic absorption spectrometry. The results obtained revealed significantly higher expressions of MMP-9 in CPTC in comparison with FPTC, as well as higher Cu/Zn ratios in CPTC than in FPTC. Thus, determining MMP-9 activities and the Cu/Zn ratios could improve the accuracy of the standard histopathological diagnosis of these two types of PTC.

Combined immunohistochemistry for thyroid peroxidase, galectin-3, CK19 and HBME-1 in differential diagnosis of thyroid tumors.

We evaluated some proposed molecular thyroid tumor markers: thyroid peroxidase (TPO), galectin-3, cytokeratin-19, and HBME-1, individually and in combination, by immunohistochemistry in a total of 242 archival thyroid tissue sections. The expression of each individual marker was most helpful for the diagnosis of papillary carcinoma and its follicular variant. However, none of them was sensitive and specific enough to discriminate between Hürthle adenoma and carcinoma. Galectin-3 and HBME-1 could be used as single discriminators between follicular thyroid adenoma and carcinoma, but HBME-1 is the better choice. As a single test, all analyzed tumor markers had sufficient power to predict differentiated thyroid cancer, with sensitivities ranging from 66.5% to 82.2%. The sensitivity was improved by using combinations of some proposed markers. Only two antigens, HBME-1 and TPO, had distinct predictive values for different diagnostic alternatives i.e. a sequential combination improved diagnostic accuracy between follicular thyroid adenoma and the follicular variant of papillary thyroid carcinoma to 92.6% and consequently, between overall benign and malignant thyroid tumors to 89.1%. HBME-1 is the most accurate ancillary stain in discriminating well-differentiated thyroid carcinomas from benign tumors, although the addition of TPO did improve accuracy and served as a useful confirmatory marker.

Expression of matrix metalloproteinase-2 and its tissue inhibitor-2 in fetal and neoplastic thyroid tissue and their significance as diagnostic and prognostic markers in papillary carcinoma.

Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) have roles in physiological and pathological processes. We evaluated immunohistochemical expression of MMP-2 and TIMP-2 in paraffin sections of 12 human fetal thyroids at mid-term gestation and 79 thyroid tumors of follicular origin. Besides evaluating expression of these proteins during fetal development and neoplastic transformation, we determined whether expression of MMP-2 and TIMP-2 may help to differentiate papillary thyroid carcinoma (PTC) from follicular thyroid adenoma (FTA) and/or peritumoral tissue (PT). We also investigated their relationship with prognostically important clinicopathological parameters of PTC. Immunoreactive MMP-2 and TIMP-2 were found in all fetal thyroid tissues examined. Tumor tissues contained variable amounts of MMP-2 and TIMP-2, with overexpression of these proteins in PTC compared to FTA and PT tissue. According to the statistical analysis, MMP-2 distinguished follicular variant of PTC from FTA and overall PTC from total nonmalignant lesions. In PTC, high MMP-2 expression correlated with lymph node metastasis (P=0.022), while high TIMP-2 expression was positively correlated with tumor size (P=0.049) and extrathyroid invasion (P=0.017). Overall, these results indicate a role for MMP-2 and TIMP-2 in both thyroid development and malignant transformation and suggest that positive immunohistochemistry for MMP-2 and TIMP-2 might support diagnosis of PTC and predict unfavorable biological behavior.

Suppressive effects of genistein and daidzein on pituitary-thyroid axis in orchidectomized middle-aged rats.

High intake of soybean phytoestrogens, isoflavones genistein (G) and daidzein (D), has been associated with health benefits. However, isoflavones were reported to affect adversely thyroid function in the presence of other goitrogenic factors. As the thyroid gland becomes functionally impaired with age, we examined whether supplementary doses of G or D would affect morphology and function of pituitary-thyroid axis in middle-aged male rats. Sixteen-month-old orchidectomized Wistar rats were treated with 10 mg/kg of either G or D, while the control sham-operated and orchidectomized group received just the vehicle for three weeks. The animals were fed soy-free diet with increased iodine content, and killed 24 h after the last treatment. Their pituitaries and thyroids were excised and prepared for further immunohistochemical and morphometric investigation. The concentrations of thyroid-stimulating hormone (TSH), total T(4) and T(3), in the serum were determined. In both isoflavone-treated groups, pituitary TSH-immunopositive cells had increased cellular volume and relative volume density (P < 0.05), as well as increased serum TSH levels (P < 0.05) in comparison to the controls; their thyroid tissue was characterized by increased volume of thyroglobulin-immunopositive epithelium (P < 0.05), epithelial height and index of activation rate (P < 0.05), while the volume of luminal colloid, and total serum T(4) and T(3) levels decreased (P < 0.05) in comparison to the controls. In conclusion, this study provides the first direct evidence that both G and D can induce microfollicular changes in the thyroid tissue and reduce the level of thyroid hormones in Orx middle-aged male rats, a model of andropause. This reduction consequently led to a feedback stimulation of pituitary TSH cells. The detected stimulatory effect was higher in the daidzein-treated rats.

Serum Cyfra 21.1 and galectin-3 protein levels in relation to immunohistochemical cytokeratin 19 and galectin-3 expression in patients with thyroid tumors.

PURPOSE: The aim of this study was to assess the clinical utility of circulating preoperative Cyfra 21.1 [soluble fragment of cytokeratin (CK) 19] and galectin-3 (gal-3) in patients with thyroid tumors, to compare their serum values with tissue expression and to analyze the prognostic significance of these markers in relation to the clinical status of postsurgical differentiated thyroid carcinoma (DTC) patients. PATIENTS: Concentrations of Cyfra 21.1 and gal-3 were evaluated by immunoassays in sera of 9 healthy subjects, 97 preoperative patients with diverse thyroid tumors (10 FTA, 63 PTC, 11 FTC, 5 PDTC, 4 ATC, 4 LNM) and 25 postoperative DTC patients (14 remissions and 11 metastases). RESULTS: Low Cyfra 21.1 values were found in all subgroups, but with a tendency toward higher values in poorly differentiated DTC patients. Compared to the control (0.23 ng/mL), serum levels of gal-3 were significantly elevated in patients with thyroid tumors but with overlapping between adenoma (4.16 ng/mL) and carcinoma (3.85, 4.37, 4.64, 6.07 ng/mL for PTC, PDTC, ATC and LNM, respectively). The tissue expression of CK19 and gal-3 was immunohistochemically determined on 45 matched paraffin-embedded sections. Most thyroid carcinomas showed positive CK19 (27/35) and gal-3 immunostaining (31/35), while adenomas were mostly immunonegative (8/10 and 7/10, respectively). However, there was no significant correlation between their serum and tissue levels. Clinical status of postoperative DTC patients had no influence on serum concentrations of the tested markers. CONCLUSIONS: While CK19 and gal-3 are accurate as tissue markers, their serum levels could not be used as reliable markers for identification of thyroid malignancy or in thyroid cancer follow-up. On the other hand, a tendency toward higher serum levels of Cyfra 21.1 in the small number of PDTC patients examined adds weight to previous reports postulating a role for cytokeratins in predicting a high degree of malignancy.

Comparison of the influence of thyroglobulin antibodies on serum thyroglobulin values from two different immunoassays in post surgical differentiated thyroid carcinoma patients.

Measurement of serum thyroglobulin (Tg) is a highly specific test in the management of patients with differentiated thyroid cancer (DTC) after surgical treatment. The aim of our study was to evaluate and compare Tg levels in these patients found by radioimmunoassay (RIA) and immunoradiometric assay (IRMA) and to assess the influence of Tg antibodies (TgAbs) on the values obtained for Tg concentration. Both Tg and TgAb were determined postoperatively in the serum of 71 DTC patients using RIA Tg-PEG (INEP) and Tg IRMA (CIS) for Tg, together with TgAb (CIS) for circulating endogenous anti-TgAbs. The obtained concentrations were evaluated statistically. We found a significant difference of Tg concentrations between paired samples from the IRMA and RIA, although the intermethod comparison yielded satisfactory concordance of the two assays (Spearman correlation coefficient -0.792). Positive TgAb was found in 28.2% of the serum samples analyzed. Spearman rank correlation analysis revealed a significant negative relationship between serum TgAb and Tg level measured by IRMA (P=0.02), but not by RIA (P=0.417). On the other hand, our clinical data revealed that 1/18 and 3/18 patients with proven lymph node metastasis had Tg values below the detection limit by RIA and IRMA assay, respectively. Their sera were TgAb positive. We concluded that RIA was less prone to influence of TgAb than IRMA. As the presence of TgAbs may interfere in Tg measurement irrespective of the method selected for determination, this should be considered during the clinical management of these patients.

Correlation of thyroglobulin concentrations measured by radioimmunoassay and immunoradiometric assay and the influence of thyroglobulin antibody.

There are a large number of commercial diagnostic assays for measuring thyroglobulin (Tg) concentration in human serum. The assay principle, as well as the potential presence of antithyroglobulin autoantibody (TgAb) in patient's serum, could influence the measured amount of Tg. Our objective was to determine the concentration of Tg by radioimmunoassay and immunoradiometric assay, to compare the values obtained and to investigate the influence of TgAbs on those results. Analysis of serum specimens (n = 58) showed close correlation between the investigated assays, regardless of the presence of TgAb in some samples. The mean value for Tg concentration, determined by radioimmunoassay, was 25% lower than that obtained by immunoradiometric assay. However, this ratio was not uniform for the whole population because the differences were more prominent for high values of Tg. The significant difference between these two methods was confirmed by Student's t-test, which indicated that patients must be monitored in continuity only by one selected method.

Thyroid peroxidase and galectin-3 immunostaining in differentiated thyroid carcinoma with clinicopathologic correlation.

Thyroperoxidase and galectin-3 have been reported as useful immunohistochemical markers of thyroid malignancy. In this study, we evaluated the relationship between immunohistochemical staining results for these markers and clinicopathologic features of patients with differentiated thyroid cancer. A total of 193 archival thyroid samples including 28 follicular adenomas, 18 follicular carcinomas, and 147 papillary carcinomas with 114 adjacent thyroid tissues were analyzed by immunohistochemistry. Thyroperoxidase was underexpressed (<50% stained thyrocytes), and galectin-3 was expressed (>5% stained thyrocytes) in most carcinomas. The sensitivity for diagnosis of differentiated thyroid carcinoma was 86.1% for thyroperoxidase and 82.4% for galectin-3, whereas the combination of both markers increased the sensitivity up to 94.5%. Thus, the combination of thyroperoxidase and galectin-3 immunohistochemistry may help to ascertain the malignant nature of the lesion. Furthermore, tumor size, nodal involvement, extrathyroidal invasion, and high tumor-node-metastasis stage in patients with papillary carcinoma were related to thyroperoxidase absence and high galectin-3 expression in most cases (P < .05). In patients with follicular carcinoma, the extent of invasiveness was associated with galectin-3 positivity. Thus, expression of these markers is related to more or less aggressive biological behavior of differentiated thyroid carcinomas. Although thyroperoxidase presence may indicate favorable prognosis of papillary cancer, expression of galectin-3 illustrates the potential importance of this protein in the pathogenesis and/or progression of differentiated thyroid carcinomas.

Apoptosis and proliferation related molecules (Bcl-2, Bax, p53, PCNA) in papillary microcarcinoma versus papillary carcinoma of the thyroid.

AIM: To gain a better insight into the differences in biological behaviour between papillary microcarcinoma (PMC) and clinically evident papillary thyroid carcinoma (PTC). METHODS: Immunohistochemical analysis of apoptosis related molecules (Bcl-2, Bax, p53) and proliferation related marker (PCNA) in 39 archival cases of PMC and 46 cases of PTC. RESULTS: Bcl-2 and Bax were expressed in most PMCs and PTCs. The average Bcl-2 staining score did not differ significantly between PMCs and PTCs (p > 0.05), but the average Bax score was significantly lower in PMCs (p < 0.05). The Bcl-2/Bax ratio was significantly higher in PMCs than in PTCs (p < 0.05). The expression of p53 was similar in PMCs and PTCs, without a correlation with clinical data, but was associated with high Bax expression (p < 0.05) in these cases in both groups. Non-malignant tissue expressed only Bcl-2, but not p53 or Bax. PCNA expression was significantly lower (p < 0.05) in PMC than in PTC and positively correlated with tumour size (p < 0.05). CONCLUSIONS: The higher Bcl-2/Bax ratio and lower proliferative activity in PMC suggest differences from PTC in the balance between apoptosis and proliferation. However, the presence of p53 and Bax in PMC indicates malignant potential, and thus PMC should be treated with caution.

Thyroid peroxidase immunohistochemistry in differential diagnosis of thyroid tumors.

Thyroperoxidase (TPO) is a thyroid-specific enzyme expressed by differentiated thyroid cells. Initial immunohistochemical studies claimed that TPO expression, detected by the monoclonal antibody mAb 47, may be a potentially important diagnostic tool in differentiating malignant from benign lesions. However, some recent studies have failed to reproduce the earlier results, suggesting the limitations for TPO immunohistochemistry. To assess these observations we have evaluated the immunohistochemical expression of TPO in thyroid tissue from 215 patients. The studied material included 87 nonmalignant thyroid lesions and 128 thyroid carcinomas. TPO expression was investigated using newly available mAb 47 and staining of less than 80% of the follicular cells/specimen as the threshold indicating a malignant lesion. We found that TPO had a sensitivity of 89.9% for cancer and a specificity of 64.4% for nonmalignant lesions, showing that it does not give a sufficient degree of diagnostic certainty that the lesion is benign. In addition, the variability in the degree of TPO expression found within and between follicular carcinomas, and the significant number of benign adenomas having similar immunostaining patterns, assured us that TPO immunostaining is not sufficiently discriminatory in the differential diagnosis of thyroid cancer versus benign lesions.