Novel acquisitions in the diagnosis of medullary thyroid carcinoma

INTRODUCTION

The correct identification of medullary thyroid carcinoma (MTC) has been a challenge since its first description. In the last few years, some advances in this context have been achieved. Here we aimed to review and discuss published data on the more recent acquisition in the diagnosis of MTC.

EVIDENCE ACQUISITION

A literature search of the medical databases was conducted by searching papers reporting tool for diagnosis of MTC published in the last years. The search was updated until July 2016.

EVIDENCE SYNTHESIS

The literature search revealed several relevant articles which focused on different topics of the diagnosis of MTC. The results are reported by four paragraphs, such as 1) fine-needle aspiration; 2) molecular analysis; 3) serum markers; 4) imaging.

CONCLUSIONS

The measurement of calcitonin in FNA washout fluids is essential due to poor accuracy of conventional cytology to detect MTC. Genetic analysis can help to identify those advanced MTC with poorer prognosis who do not respond to chemotherapy. Procalcitonin may in the next future replace calcitonin as serum diagnostic marker of MTC. Recent evidence based data seem to suggest the emerging role of functional imaging in recurrent MTC in patients with calcitonin serum levels >150 pg/mL.

Galectin-3 and HBME-1 improve the accuracy of core biopsy in indeterminate thyroid nodules

Core needle biopsy (CNB) has been recently described as an accurate second-line test in thyroid inconclusive cytology (FNA). Here we retrospectively investigated the potential improvement given by Galectin-3, Cytokeratin-19, and HBME-1 on the accuracy of CNB in thyroid nodules with prior indeterminate FNA report. The study included 74 nodules. At CNB diagnosis, 15 were cancers, 40 were benign, and 19 had uncertain/non-diagnostic CNB report. The above immunohistochemical (IHC) panel was analyzed in all cases. After surgery, 19 malignant and 55 benign lesions were found. All 15 cancers and all 40 benign nodules diagnosed at CNB were confirmed at final histology. Regarding the uncertain CNB group, 4 (21 %) were malignant and 15 (79 %) benign. When we considered all the series, the most accurate IHC combination was Galectin-3 plus HBME-1, while HBME-1 was the most sensitive marker in those nodules with uncertain CNB report. The combination of CNB plus IHC could indentify 19/19 cancers and 53/55 benign lesions. Sensitivity and specificity of CNB increased from 79 to 100 % and from 73 to 96 %, respectively, by adding IHC. CNB can diagnose the majority of thyroid nodules with previous indeterminate FNA cytology, while the accuracy of CNB is increased by adding Galectin-3, Cytokeratin-19, and HBME-1 panel. We suggest to adopt CNB as a second-line approach to indeterminate thyroid FNA, and apply IHC in those lesions with uncertain/non-diagnostic CNB report. This approach should improve the pre-surgical diagnosis of patients. These results should be confirmed in larger prospective series.

Ultrasound features of medullary thyroid carcinoma correlate with cancer aggressiveness: a retrospective multicenter study

Background

Poor prognosis of medullary thyroid cancer (MTC) with suspicious ultrasound (US) features has been reported. The aim of the study was to investigate the association between preoperative US presentation and aggressiveness features of MTC. Also, US features of MTC were compared with those previously reported.

Methods

Study group comprised 134 MTC from nine different centers. Based on US presentation the nodules were stratified in “at risk for malignancy” (m-MTC) or “probably benign” (b-MTC) lesions.

Results

Eighty nine (66.4%) m-MTC and 45 (33.6%) b-MTC were found. Metastatic lymph nodes (p = 0.0001) and extrathyroid invasiveness (p < 0.0001) were more frequent in m-MTC. There was statistically significant correlation (p = 0.0002) between advanced TNM stage and m-MTC with an Odds Ratio 5.5 (95% CI 2.1–14.4). Mean postsurgical calcitonin values were 224 ± 64 pg/ml in m-MTC and 51 ± 21 in b-MTC (p = 0.003).

Conclusions

This study showed that sonographically suspicious MTC is frequently associated with features of aggressiveness, suggesting that careful preoperative US of MTC patients may better plan their surgical approach.

Clinical characteristics as predictors of malignancy in patients with indeterminate thyroid cytology: a meta-analysis

Indeterminate thyroid nodules (ITN) constitute the gray zone of thyroid fine-needle aspiration cytology (FNAC). About 70-80 % of ITN are later diagnosed as benign; therefore, it is very important to identify the predictors of malignancy. Aim of the study was to summarize published data about clinical risk factors for malignancy in patients with ITN and thereby provide more robust estimates of the effect of these risk factors. Sources comprised studies published through December 2012. Original articles that investigated clinical parameters as potential predictors of malignancy in ITN were identified. Two authors performed the data extraction independently. A meta-analysis of 19 relevant studies was conducted that included 3,494 patients with ITN according to FNAC. The pooled prevalence of malignancy was 28 % (95 % CI 23-33), 26 % in females and 34 % in males. The pooled OR was 1.51 (95 % CI 1.2-1.83) for males and 0.68 (95 % CI 0.53-0.88) for females. Regarding the nodule's size, the pooled OR was 2.10 (95 % CI 1.26-3.50) for nodules >4 cm in diameter. Analysis of the patient age as a risk factor was not feasible because of marked difference found between the studies. In patients with indeterminate thyroid nodules diagnosed at FNAC, the pooled rate of malignancy from 19 studies was 28 %. Patients that are male and have ITN greater than 4 cm in diameter should be considered at higher risk of cancer.

Calcitonin measurement in aspiration needle washout fluids has higher sensitivity than cytology in detecting medullary thyroid cancer: a retrospective multicentre study

OBJECTIVE

Only few studies analysed the capability of cytology in detecting medullary thyroid cancer (MTC), and they reported a low accuracy of this diagnostic technique. Recently, calcitonin (CT) measurement in aspiration needle washout (FNA-CT) of thyroid and neck lesions has been reported as a sensitive tool for MTC. The aim of this study is to compare the sensitivity of FNA-CT and cytology in detecting MTC and to assess a cut-off value of FNA-CT for clinical practice.

PATIENTS

Thirty-eight MTC lesions from 36 patients were retrospectively studied, diagnosed and treated in four different centres. Furthermore, 52 nonmedullary lesions from subjects undergone biopsy following increased serum CT were collected as a control group.

RESULTS

Cytology detected MTC in 21/37 lesions with 56·8% sensitivity. The median FNA-CT value was 2000 pg/ml (range 58-10 000 pg/ml) in MTC and 2·7 pg/ml (range <2-13 pg/ml) in controls (P < 0·001). Using a cut-off of 39·6 pg/ml, MTC lesions could be identified with 100% sensitivity and specificity. As the most important finding, 14 histologically proved MTC lesions could be detected by FNA-CT, despite they were cytologically diagnosed as benign or nonconclusive.

CONCLUSIONS

This study shows, as the first in a multicentre series, that FNA-CT sensitivity is higher than that of cytology in diagnosing MTC. To avoid false-negative MTC by cytology, CT measurement in aspiration needle washout is to be performed in all patients undergoing biopsy following high serum CT.

Diagnostic performance of (99m)Tc-MIBI scan in predicting the malignancy of thyroid nodules: a meta-analysis

Several studies have investigated the diagnostic performance of (99m)Tc-MIBI scan in the evaluation of thyroid nodules suspicious for malignancy with conflicting results. The aim of our study is to meta-analyze published data on this topic. A comprehensive literature search of studies published through December 2012 regarding the diagnostic performance of (99m)Tc-MIBI scan in the evaluation of thyroid nodules suspicious for malignancy was carried out. Pooled sensitivity and specificity of (99m)Tc-MIBI scan on a per lesion-based analysis and the area under the ROC curve were calculated. Pathological reports of thyroid nodules were considered as reference standard. Twenty-one studies were included in the meta-analysis. Pooled sensitivity and specificity of (99m)Tc-MIBI scan in detecting malignant thyroid nodules were 85.1 % [95 % confidence interval (95 % CI): 81.1-88.5 %] and 45.7 % (95 % CI: 42.7-48.7 %), respectively, on a per lesion-based analysis, irrespective of eventual results of previous technetium pertechnetate ((99m)TcO4) or iodine-123 ((123)I) scan. The area under the ROC curve was 0.78. A sub-analysis restricted to data on hypofunctioning nodules on (99m)TcO4 or (123)I scans was performed: pooled sensitivity and specificity of (99m)Tc-MIBI scan in these nodules were 82.1 % (95 % CI: 77.2-86.3 %) and 62.8 % (95 % CI: 58.9-66.7 %), respectively, on a per lesion-based analysis. The area under the ROC curve was 0.81. (99m)Tc-MIBI scan is a sensitive diagnostic tool in predicting the malignancy of thyroid nodules. Therefore, this imaging method could be helpful in patients with thyroid nodules in which malignancy is suspected on the basis of conventional diagnostic techniques. Higher specificity can be reached when hypofunctioning thyroid nodules are considered.

Mammalian target of rapamycin pathway activation is associated to RET mutation status in medullary thyroid carcinoma

CONTEXT

The genetic pathways involved in medullary thyroid carcinomas (MTC), except for RET mutations, are largely unknown, as is the detailed mapping of proteins activated as a consequence of RET tyrosine kinase phosphorylation.

OBJECTIVE

The present study was designed to screen for the presence of mutations in other genes downstream to RET activation and to detect the activation patterns of a panel of intracellular regulators of cell growth.

DESIGN

Forty-nine cases of MTC were analyzed for mutations in RET, BRAF, N-, H-, and K-RAS, and phosphatidylinositol-3 (PI3) kinase genes. Immunohistochemical analysis was performed using antibodies against several intracellular transducers. The effect of mammalian target of rapamycin (mTOR) inhibition was assessed in vitro onto TT cells by means of methyl thiazolyl tetrazolium and Western blot assays.

RESULTS

BRAF, K-, H-, and N-RAS, and PI3 kinase mutations were absent in all cases examined. Germline RET mutations were detected in 20% of cases overall, whereas somatic RET mutations represented 53% of sporadic tumors. RET mutational status was associated to age, presence of multifocal tumors, and nodal status, but not disease outcome. Protein expression of markers investigated was highly heterogeneous, with a strong association between phospho-mTOR, phospho-AKT, and phospho-p70S6K, positively correlated to the presence of germline RET mutations. Moreover, selective mTOR inhibition affected cell proliferation of RET-mutant TT cells.

CONCLUSIONS

Taken together, our findings indicate that mTOR intracellular signaling pathway is functionally activated in MTC with a preferential expression in cases with germline RET mutations; genes downstream to RET tyrosine kinase such as BRAF, RAS isoforms, and PI3 kinase are not mutated in MTC.

99mTc-MIBI Imaging in the presurgical characterization of thyroid follicular neoplasms: relationship to multidrug resistance protein expression

Recently, thyroid (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) scintiscanning has been proposed in an attempt to preoperatively identify thyroid malignancies, but discrepant results have been reported for oncocytic lesions. The aim of this study was to investigate the usefulness of visual and semiquantitative analyses of (99m)Tc-MIBI scintigraphy for preoperatively characterizing thyroid nodules with indeterminate cytologic diagnoses, segregating in advance nononcocytic variants from those that are oncocytic. This study also aimed to analyze the relationship between (99m)Tc-MIBI images and P-glycoprotein (P-gp)/multidrug resistance-associated protein-1 (MRP1) immunohistochemical expression.

METHODS

Fifty-one consecutive patients with cold thyroid nodules cytologically diagnosed as nononcocytic or oncocytic follicular neoplasm were prospectively studied. Visual and semiquantitative (99m)Tc-MIBI scanning was performed and the diagnoses of the lesions were histologically proven by subsequent thyroidectomy. Immunohistochemical evaluation of P-gp and MRP1 was also performed on surgical samples.

RESULTS

Visual and semiquantitative (99m)Tc-MIBI scintiscans showed a low specificity in preoperatively discriminating malignant oncocytic lesions. In nononcocytic nodules, the semiquantitative method was more accurate than the visual (94.44% and 77.78%, respectively). P-gp protein expression was negative in all thyroid lesions, whereas apical plasma membrane MRP1 expression was found in 78% of the lesions with a negative (99m)Tc-MIBI retention index, compared with 11% of lesions with a positive retention index, correlating most strongly with a negative (99m)Tc-MIBI RI in those cases with strong MRP1 apical expression.

CONCLUSION

Semiquantitative (99m)Tc-MIBI scintigraphy is an adjunctive method to predict preoperatively the malignant behavior of nononcocytic follicular thyroid nodules indeterminate at fine-needle aspiration biopsy, with a potential impact on the definition of their clinical management. Moreover, the good correlation found between immunohistochemical apical expression of MRP1 and the scintigraphic findings supports the (99m)Tc-MIBI results and provides tissue information on the molecular mechanisms responsible for (99m)Tc-MIBI images in thyroid lesions.

Absence of RET gene point mutations in sporadic thyroid C-cell hyperplasia

Progression from C-cell hyperplasia (CCH) to medullary thyroid carcinoma (MTC) has been demonstrated to date only in familial forms, whereas in nonfamilial MTC, such hypothesis is suggested by the rare concurrence of both lesions, although no epidemiological and molecular data are available to prove or disprove this event. Therefore, the clinical management of patients with sporadic CCH is controversial. To evaluate the malignant potential of sporadic CCHs, pure laser-microdissected C-cell populations of 24 CCH cases, either reactive or associated with nonfamilial MTC, were analyzed for MTC-associated protein neural cell adhesion molecule expression and RET point mutations in exons 10, 11, 15, and 16, by using immunohistochemistry and polymerase chain reaction-single-strand conformation polymorphism/heteroduplex electrophoresis/direct sequencing, respectively. No RET mutations were found in any of the 24 CCH cases, whereas M918T mutation was detected in three concomitant MTCs. Neural cell adhesion molecule was immunoreactive in the majority of CCH associated with MTC even in the absence of morphological atypia, but not in reactive forms. The absence of RET alterations in all cases of CCH examined supports the hypothesis that the development of MTC is independent of pre-existing CCH in the nonfamilial setting; thus, sporadic CCH should not be considered a risk factor for nonfamilial MTC.

Galectin-3 and Ki-67 expression in multiglandular parathyroid lesions

Hyperplastic and neoplastic parathyroid lesions may present overlapping morphologic features, and several markers have been proposed to distinguish benign from malignant growths. Recently, it was reported that galectin-3 is a useful marker of malignancy in uniglandular parathyroid diseases. To investigate galectin-3 and Ki-67 immunoexpression in parathyroid hyperplastic disease, 63 multiglandular lesions (13 primary, 40 secondary, and 10 tertiary hyperplasia cases) were analyzed and compared with 45 control cases of parathyroid adenomas and 24 carcinomas. Our data showed that hyperplastic lesions responsible for primary nonfamilial or tertiary hyperparathyroidism, as well as parathyroid adenomas, were negative for galectin-3, as opposed to carcinomas. In addition, secondary and familial primary hyperplasia cases were surprisingly positive for galectin-3 in approximately two thirds of cases. All hyperplastic lesions (positive or negative for galectin-3) had a low Ki-67 index. Based on these findings, secondary hyperplasia has a low proliferative potential but an unexplained galectin-3 reactivity, which reduces its diagnostic role in differentiating benign from malignant nodules in the context of multiglandular parathyroid diseases.

Goiter prevalence and urinary iodine status in urban and rural/mountain areas of Piedmont region

Piedmont region was reported in the 70s as a mild iodine-deficient area with a goiter prevalence > 10%. This study aimed at characterizing the current status of iodine deficiency in Piedmont, with special attention to putative differences between urban and rural/mountain areas. A cross-sectional, observational study was performed according to the surveillance methods for iodine deficiency disorders recommended by the World Health Organization (WHO). Ultrasound local thyroid volume reference values and median urinary iodine concentration were obtained in 2178 schoolchildren aged 11-15 yr, resident in Piedmont region for more than 5 yr to assess both goiter prevalence and iodine intake. Anamnestic and anthropometric data, thyroid volume by both bimanual palpation and ultrasound were assessed, and spot urinary iodine samples were collected. The median urinary iodine concentration was 115.8 microg/l and the prevalence of goiter 3.1%, indicating this area as iodine-sufficient. Nevertheless, 39% of the schoolchild population had urinary iodine levels < 100 microg/l and 6.8% < 50 microg/l. No differences in goiter prevalence and median urinary iodine excretion were observed between urban and rural/ mountain populations. In conclusion, Piedmont is now an iodine-sufficient region. As no programs of salt iodization have been carried out in the last 30 yr, a silent iodine replacement has occurred. Despite a sufficient median urinary iodine excretion, a program of iodine prophylaxis is strongly recommended due to a large part of iodine-deficient population.

Characterization of thyroid 'follicular neoplasms' in fine-needle aspiration cytological specimens using a panel of immunohistochemical markers: a proposal for clinical application

The distinction of benign from malignant follicular thyroid neoplasms remains a difficult task in diagnostic fine-needle aspiration cytology, and some discrepant results have been reported for the individual immunocytochemical markers of malignancy proposed so far. The aim of this study was to test if the combined use of a panel of markers could improve the diagnostic accuracy in the preoperative cytological evaluation of 'follicular neoplasms' in an attempt to reduce the number of thyroidectomies performed for benign lesions. The immunocytochemical expression of galectin-3, HBME-1, thyroperoxidase, cytokeratin-19 and keratan-sulfate was retrospectively analyzed in 125 consecutive fine-needle aspiration samples (cell blocks) of indeterminate diagnoses of 'follicular thyroid neoplasm', and compared with their corresponding surgical specimens, including 33 follicular carcinomas, 42 papillary carcinomas and 50 follicular adenomas. Statistical analysis on each marker confirmed that galectin-3 and HBME-1 were the most sensitive (92% and 80% respectively) and specific (94% and 96% respectively) molecules. The use of these two markers sequentially in non-oncocytic lesions (testing HBME-1 as a second marker whenever galectin-3 proved negative) increased the sensitivity and specificity up to 97% and 95% respectively. In oncocytic lesions, HBME-1 proved to be less sensitive, and the sequential combination of galectin-3 and cytokeratin-19 reached 100% of both specificity and sensitivity. Our data showed that, as compared with the use of single markers, the sequential combination of two markers represents the most accurate immunohistochemical panel in managing patients with a fine-needle aspiration biopsy diagnosis of 'follicular neoplasms', especially in otherwise controversial categories such as oncocytic tumours. The combination of three or more markers did not substantially improve the diagnostic accuracy of the test.

Galectin-3 and HBME-1 expression in oncocytic cell tumors of the thyroid

Oncocytic cell tumors (OCTs) of the thyroid include oncocytic cell adenomas (OCAs) and oncocytic cell carcinomas (OCCs). Oncocytic variant of papillary carcinoma (OVPC) has also been described. These tumors may present similar diagnostic problems as their non-oncocytic counterparts, in both conventional histology and fine-needle aspiration biopsies. Several markers were shown able to distinguish benign from malignant thyroid follicular tumors, galectin-3 and HBME-1 being the most promising ones. Controversial data have been reported on their discriminatory potential in the small series of OCTs so far analyzed. We aimed to assess the role of galectin-3 and HBME-1 in a large series of 152 OCTs (including 50 OCAs, 70 OCCs and 32 OVPCs). The expression of PPARgamma protein was also evaluated. Using a biotin-free detection system, the sensitivity of galectin-3 was 95.1%, while that for HBME-1 was nearly 53%. The combination of galectin-3 and HBME-1 increased the sensitivity up to 99%. However, for both markers, the specificity was 88%, lower than that reported for non-oncocytic follicular tumors. PPARgamma protein overexpression was absent in all OCAs tested and present in only 10% of OCCs, confirming previous reports on the low prevalence of PAX8-PPARgamma translocations in OCT and ruling out its role as a potential diagnostic marker of malignancy.

Thyroid volume and urinary iodine excretion in the schoolchild population of a Northwestern Italian sub-Alp metropolitan area

Iodine deficiency is recognised as a major preventable public-health worldwide problem. The aim of this study is to assess local reference values for thyroid volume, and give a snapshot of the epidemiology of goiter and iodine nutritional status of the Turin schoolchild population. Sonographic thyroid volume and median urinary iodine excretion were obtained in 1067 schoolchildren aged 11-15 yr resident in Turin for more than 5 yr to assess both goiter prevalence and iodine intake. All the subjects were asked to fill in a questionnaire about their life habits. Anamnestic and anthropometric data, thyroid volume by both bimanual palpation and ultrasonography were assessed, and spot urinary iodine samples were collected. The results show that the median urinary iodine concentration is 113.1 microg/l and the prevalence of goiter <5%, indicating this area as iodine-sufficient. Nevertheless, 40.5% of the schoolchild population has urinary iodine levels lower than the cut-off level recommended as iodine-sufficiency. Interestingly, the high relative prevalence of ultrasound features of autoimmune thyroid disease suggests autoimmune-thyroiditis as a frequent thyroid disease in Turin schoolchildren. As no active programs of salt, milk or water iodisation have ever been carried out, a silent iodine prophylaxis has probably occurred in the city. Despite a sufficient median urinary iodine excretion, a focused program of iodine prophylaxis should be developed due to the presence of a large rate of iodine-deficient population.

Galectin-3: presurgical marker of thyroid follicular epithelial cell-derived carcinomas

Preoperative follicular lesion characterisation represents an unsolved diagnostic problem in thyroid nodular disease. Although fine-needle aspiration biopsy is the most reliable preoperative diagnostic procedure, it shows inherent limitations in differentiating adenoma from follicular carcinoma and, sometimes, follicular variants of papillary carcinoma. Galectin-3 cytoplasmic neoexpression has been proposed as a peculiar feature of thyroid malignant cells, easily detectable in cytological and histological samples. The aim of this study was to re-evaluate the galectin-3 expression in a large sample of thyroid lesions using an immunohistocytochemical biotin-free detection system and a specific anti-human-galectin-3 monoclonal antibody in order to avoid the interference of technical factors, a cause of conflicting results recently reported by some authors. We analysed galectin-3 expression of 39 follicular carcinomas, 26 papillary carcinomas, and 105 adenomas in both cell-block samples and their histological counterparts. All cell-block and histological papillary carcinoma samples showed high levels of galectin-3 immunoreactivity. Thirty-four follicular carcinomas were positive, whereas 5 were negative in cell-blocks but positive in their histological counterparts. Twelve out of 105 adenomas expressed galectin-3 in cell-blocks and histological samples. The diagnostic accuracy of preoperative galectin-3 evaluation in adenomas vs follicular carcinomas was 90.0%. Galectin-3 expression was also investigated in 22 minimally-invasive follicular carcinomas. All of them showed galectin-3 immunoreactivity in both cytological and histological specimens with the exception of two cases, where galectin-3 positivity was observed only in the surgical material. The routine correct use of galectin-3, by increasing the diagnostic accuracy of conventional cytology, improves the management of thyroid nodules and can lead to a sensitive reduction of useless thyroid surgeries.

Role of galectin-3 immunodetection in the cytological diagnosis of thyroid cystic papillary carcinoma

OBJECTIVE

Cystic thyroid lesions can harbour an occult papillary carcinoma, which fine needle aspiration (FNA) biopsy may fail to detect. Recently, new markers such as galectin-3 lectin have been proposed to distinguish benign from malignant thyroid lesions of follicular origin. The aim of this study was to assess the role of galectin-3 immunodetection in a series of FNA cytological samples of benign and malignant thyroid cystic nodules.

METHODS

We retrospectively analysed galectin-3 expression by immunoperoxidase staining on 32 cytological paraffin-embedded samples of cystic papillary carcinoma and on 12 samples of benign cysts, both obtained by FNA biopsy. Specificity, sensitivity, positive/negative predictive values, and accuracy of standard cytological examination and galectin-3 immunodetection were assessed.

RESULTS

Among cystic papillary carcinomas, 29 of 32 samples were galectin-3 positive, whereas standard FNA cytology made a correct diagnosis in only 25 of 32 samples. All the benign cysts were negative for galectin-3. In comparing the sensitivity and specificity of the two methods, it appeared that both had a 100% specificity, whereas the sensitivity of cytological examination alone was 75% versus 89.3% obtained by galectin-3 immunohistochemistry.

CONCLUSIONS

Galectin-3 immunostaining represents a valid pre-operative adjunct to pick up malignant cells in those cases where a very poor number of epithelial cells may lead to a cytological misdiagnosis. Therefore, we suggest that in poorly cellular FNA biopsies of simple or complex thyroid cysts, galectin-3 expression by epithelial cells is consistent with a cystic carcinoma and supports surgical treatment indication.

Galectin-3 as a presurgical immunocytodiagnostic marker of minimally invasive follicular thyroid carcinoma

Thyroid nodules are a common occurrence in the general population, but only a small number of them are eventually diagnosed as cancers. Fine-needle aspiration biopsy (FNAB) is the most accurate and cost-effective method for the presurgical management of thyroid nodules, but it misses the differential diagnosis between thyroid follicular adenomas and follicular carcinomas. Among them, minimally invasive follicular carcinoma (MIC), also defined as encapsulated tumor, only differs from follicular adenoma for the exhibition of minimal, but entire thickness, infiltration of the capsule and/or vascular invasion. This feature cannot be assessed in FNAB and can occasionally be hard to recognize in surgical specimens. As reported in several studies, galectin-3 is a reliable marker of thyroid malignancy, but no data are available on MICs. We analyzed the immunohistochemical expression of galectin-3 in 17 MICs and 52 follicular adenomas in both preoperative paraffin-embedded cytological human thyroid sediments (cell blocks) obtained by FNAB and in the corresponding surgical specimens. Among the MICs, all surgical samples showed galectin-3 immunoreactivity in the cytoplasm, whereas 16 of 17 corresponding FNAB cell blocks were positive. No evidence of cytoplasmic galectin-3 expression was observed in 48 of 52 adenomas in both cell blocks and histological tissues. These findings indicate that galectin-3 is a reliable presurgical molecular marker of MIC, improving the accuracy of conventional FNAB. It also proves to be useful in the histopathological assessment of resected tumors having suspected malignant features.

Treatment of medullary thyroid carcinoma: an update

Prognosis and treatment effectiveness of medullary thyroid carcinoma (MTC) are largely related to the tumour stage, so that early diagnosis represents an important goal for the management of patients. Recent advances in genetic testing have improved the clinical approach to the familial MTC syndromes. There is general agreement that the primary operation for MTC should obtain the complete removal of the neoplastic tissue in the neck, because any adjuvant treatment has never been proven to be effective. The management of residual/recurrent or metastatic MTC still remains controversial, although a multimodal approach to advanced disease may be of value in palliation or local control of tumour progression. The role of surgery, external radiotherapy, radionuclide therapy and medical treatment, including biological response modifiers and cytotoxic drugs, are reviewed and discussed.

Tubercular involvement of the thyroid gland: a report of two cases

Thyroid tuberculosis is rare. In the last decade, however, the incidence of extrapulmonary forms of tuberculosis has increased. We report on 2 cases of thyroid tuberculosis. In case 1, a tubercular abscess mimicking acute thyroiditis was found which was correctly diagnosed by fine-needle aspiration biopsy (FNAb). No evidence of active disease was noticed. Pleural thickening on chest X-ray was the only sign compatible with a previous infection. In case 2, tubercular thyroiditis with lymph node enlargement was also diagnosed by FNAb in a reevaluation setting. In both cases treatment with antitubercular drugs resulted in complete recovery. Thyroid tuberculosis should be kept in mind in the differential diagnosis of thyroid nodules, notably in patients with a history of tuberculous disease. FNAb represents the main approach to making the diagnosis.

Galectin-3 is a presurgical marker of human thyroid carcinoma

Galectin-3 is a carbohydrate-binding protein endowed with an affinity for beta-galactosides. It has been shown to play an important role in cell-cell and cell-matrix interactions and in pre-mRNA splicing. Furthermore, it is involved in the control of cell growth, neoplastic transformation, and metastasis. Interestingly, high levels of galectin-3 expression have been recently described in malignant thyroid neoplasias, but not in adenomas or in normal thyroid tissue. We investigated galectin-3 expression in human presurgical specimens obtained by fine-needle aspiration biopsy. We analyzed galectin-3 expression by immunoperoxidase staining in both paraffin-embedded cytological thyroid sediments (cell blocks) obtained by fine-needle aspiration biopsy and their histological counterparts. A total of 64 samples were examined: 17 follicular carcinomas; 18 papillary carcinomas; and 29 follicular adenomas. All cell blocks and histological samples of papillary carcinomas expressed high levels of galectin-3 at either the cytoplasmic or nuclear level. Among follicular carcinomas, all histological samples expressed galectin-3, whereas 14 of 17 corresponding cell blocks were positive in the cytoplasm. No evidence of cytoplasmic galectin-3 expression was observed in 26 of 29 follicular adenomas. Hence, cytoplasmic galectin-3 staining seems to be a reliable, easy, and cheap marker for presurgical diagnosis of follicular carcinomas and an even more suitable one for papillary carcinomas.

Changes in integrin and E-cadherin expression in neoplastic versus normal thyroid tissue

BACK: The functional organization of polarized epithelia depends mostly on adhesion molecules belonging to the integrin and cadherin families. These molecules either recognize basement membrane components, such as laminins, or form intercellular junctions via homotypic interactions. Such tissue organization is often disrupted upon neoplastic transformation, and the resulting loss of functional polarization and cell cohesion might be a prerequisite for the invasive and metastatic behavior of carcinomas.

PURPOSE

We studied modifications on thyroid adhesive mechanisms at various stages of neoplastic progression in terms of adhesion molecule expression, topography, and functional regulation by tyrosine kinases. Starting from this working hypothesis, we sought to identify one or more biological markers that would be suggestive of malignant transformation and poorer prognosis and that could be developed as a reliable indicator(s) in early diagnostic steps.

METHODS

The study was carried out on both surgical samples and the corresponding fine-needle aspiration biopsy smears (numbers of specimens collected: 19 adenomas, seven follicular carcinomas, 13 papilary carcinomas, and 39 normal tissues). Immunohistochemistry of tissue sections and smears and immuno-precipitation and western blot analysis of protein extracts were done with a battery of monoclonal and polyclonal antibodies. Northern blotting was performed on RNA extracts from frozen tissue samples and use of an integrin subunit beta4 complementary DNA probe.

RESULTS

Our findings can be summarized as follows: 1) In normal thyroid cells, the cooperative role of integrin alpha6beta4 and laminin 5/kalinin in hemidesmosome-mediated adhesion adhesion is missing, and recognition of the basal lamina occurs via integrin alpha3beta1 and laminin 1 and/or 2 (this pattern being maintained in adenomas but altered in carcinomas regardless of their histotype or differentiation grade); 2) only in carcinomas with clinical and/or histologic aggressiveness do neoexpression of integrin subunit beta4 and loss of laminin 2/merosin occur, indicating de novo assembly of integrin alpha6beta4; 3) pericellular redistribution and cytoskeletal disconnection of the E-cadherin-catenin complex occur; and 4) basal E-cadherin tyrosine phosphorylation decreases in carcinomas as compared with that in normal and adenomatous tissue.

CONCLUSION

The malignant progression of thyroid tumors involves marked rearrangement of cell-basement membrane and cell-cell adhesion molecules and changes in their cytoskeleton linkage. These rearrangements are also easily and reproducibly detected on fine-needle aspiration biopsy smears.

IMPLICATIONS

Immunodetection of adhesion molecules in sections and/or fine-needle smears may complement the toolbox of thyroid surgical pathologists; it may expand the possibilities of achieving a correct early diagnosis of thyroid tumors and of gaining some prognostic information on thyroid tumors.