Immunostaining of galectin-3 and CD44v6 using fine-needle aspiration for distinguishing follicular carcinoma from adenoma

To evaluate the clinical applicability of galectin-3 and CD44 variant 6 (CD44v6) immunostaining in fine-needle aspiration cytology (FNAC) of thyroid follicular tumors, 79 cytological specimens (35 follicular carcinomas and 44 follicular adenomas) were studied. The positive rates of galectin-3 and CD44v6 were 89 and 74% in follicular carcinoma, respectively, and 25 and 30% in follicular adenoma, respectively. There were no significant correlations between the expression of galectin-3 or CD44v6 in follicular carcinoma and characteristics such as capsular invasion, vascular invasion, metastasis, or tumor size. Positive staining of either galectin-3 or CD44v6 resulted in a diagnostic sensitivity of 97% and a specificity of 52% for follicular carcinoma among follicular tumors. Immunostaining of galectin-3 or CD44v6 using cytological specimens can provide independent information on conventional morphological findings of cytology to distinguish follicular carcinoma from adenoma.     

Galectin-3 and HBME-1 expression in well-differentiated thyroid tumors with follicular architecture of uncertain malignant potential.

Well-differentiated encapsulated tumors of the thyroid gland with a follicular architecture may cause diagnostic difficulties. Questionable vascular or capsular penetration may raise the possibility of a follicular carcinoma, while focal nuclear clearing and grooves may suggest a diagnosis of papillary carcinoma. A proposal has recently been made to designate cases showing suggestive but not conclusive morphological evidence of malignancy along these lines as well-differentiated or follicular tumors of uncertain malignant potential. The aim of the present study was to investigate the expression and diagnostic role in well-differentiated or follicular tumors of uncertain malignant potential of Galectin-3 and HBME-1, two malignancy-related markers. A total of 21 tumors fulfilling the criteria of well-differentiated or follicular tumors of uncertain malignant potential were collected from two institutions, including eight cases with questionable vascular and/or capsular invasion and 13 cases with some degree of nuclear changes in the form of clearing, grooves, and/or pseudoinclusions. Tumors in the first group expressed HBME-1 and Galectin-3 focally (less than 25% of tumor cells) in 5/8 and 3/8 cases, respectively, with 62.5% of cases reacting for at least one marker. Cases in the second category expressed HBME-1 and Galectin-3 in 9/13 and 10/13 cases, respectively, with 92.3% of cases having at least one marker expressed. These findings indicate that HBME-1 and Galectin-3 are heterogeneously distributed in these borderline tumors, but that a strong and diffuse expression of HBME-1 and to a lower extent of Galectin-3 was preferentially observed in the group characterized by nuclear changes which were similar but less developed than those of conventional papillary carcinoma. The relationship found between the markers investigated and these nuclear changes suggests that the tumors containing them are pathogenetically linked to papillary carcinomas.     

Cell proliferation marker MCM2, but not Ki67, is helpful for distinguishing between minimally invasive follicular carcinoma and follicular adenoma of the thyroid

AIMS: To compare cell proliferation markers, minichromosome maintenance protein 2 (MCM2) and Ki67, in minimally invasive follicular carcinoma (MIFC) and follicular adenoma (FA) of the thyroid and among MIFCs with different diagnostic criteria. METHODS AND RESULTS: Twenty-two MIFCs and 20 FAs were immunohistochemically stained for MCM2 and Ki67. The MIFCs were subdivided into six Group 1 tumours with both capsular and vascular invasions, seven Group 2 tumours with vascular invasion only and nine Group 3 tumours with capsular invasion only. The MCM2 and Ki67 indices were calculated, counting more than 1000 tumour cells in the most frequently positive areas. In total and Groups 1-3 MIFCs and in FAs, the average MCM2 index was 26.7 +/- 11.0, 28.4 +/- 8.6, 26.3 +/- 14.8, 25.9 +/- 8.4 and 10.7 +/- 4.5, respectively, whereas the average Ki67 index was 2.07 +/- 1.65, 1.93 +/- 2.02, 2.49 +/-1.38, 1.84 +/- 1.5 and 1.78 +/- 0.92, respectively. There was a significant difference in the MCM2 index, but not in the Ki67 index, between each category of MIFCs and FA (P < 0.01). However, neither the MCM2 index nor the Ki67 index showed a statistically significant difference among the subgroups of MIFC. CONCLUSIONS: MCM2, but not Ki67, is a helpful marker for differentiating MIFC from FA. The tumour cell proliferative activity supports the histological criteria based on diagnosing MIFC by either capsular or vascular invasion only.     

Diagnostic usefulness of dipeptidyl aminopeptidase IV monoclonal antibody in paraffin-embedded thyroid follicular tumours.

Monoclonal antibodies to dipeptidyl aminopeptidase IV (DAP IV, EC 3.4.14.5) were raised and selectively applied to paraffin-embedded sections of thyroid carcinoma. Five monoclonal antibodies were found to stain paraffin sections of thyroid carcinomas. Using one of these antibodies (44-4), we studied retrospectively aberrant expression of DAP IV in thyroid carcinoma to determine whether immunohistochemical staining with DAP IV antibody is useful in pathological diagnosis. In almost all cases of thyroid follicular and papillary carcinoma, tumour cells were positive (99.0 per cent) with DAP IV, whereas the cases of follicular adenoma showed a low incidence (27.1 per cent) of positive staining. Follicular adenoma with incomplete capsular invasion had a higher positive incidence (50 per cent) than follicular adenoma without incomplete capsular invasion (9.6 per cent). In positive staining cases previously diagnosed as benign tumours, 11 benign cases reacting positively with DAP IV were rediagnosed as carcinoma after re-examination of more thyroid paraffin block sections or serial sections. These findings suggest that DAP IV monoclonal antibody is very useful in distinguishing thyroid follicular carcinoma from follicular adenoma.     

Hyalinizing trabecular carcinoma of thyroid gland

We describe two cases of encapsulated thyroid tumours which displayed the classic morphological features of hyalinizing trabecular adenoma. In addition, both were characterized by focal invasion of the capsule and of thin-walled capsular blood vessels. Positive immunohistochemical staining of tumour cells for thyroglobulin and negative staining for calcitonin, chromogranin and CEA allowed distinction from medullary carcinoma. Electronmicroscopy revealed groups of tumour cells, surrounded by abundant basement membrane type material. Occasional tumour cells contained abundant cytoplasmic intermediate filaments. A flow cytometric analysis revealed one tumour to have a diploid DNA pattern and the other to be DNA aneuploid. These cases illustrate that a malignant variant of hyalinizing trabecular adenoma, namely hyalinizing trabecular carcinoma, exists. Hyalinizing trabecular tumours of the thyroid should not be considered uniformly benign lesions. As with follicular neoplasms, multiple sections from the capsule should be examined histologically in order to assess the presence or absence of capsular and/or vascular invasion.     

Why do frozen sections have limited value in encapsulated or minimally invasive follicular carcinoma of the thyroid?

The diagnosis of encapsulated or minimally invasive follicular carcinoma of the thyroid requires the proof of vascular or capsular invasion. The aim of the present study was to evaluate the relationship between intraoperative diagnosis (benign, suggestive of carcinoma, or malignant) and the final histopathologic criteria for encapsulated or minimally invasive follicular carcinoma (tumor size, capsular invasion, vascular invasion, and differentiation). This was a retrospective study of 63 cases of encapsulated or minimally invasive carcinomas, with the final histopathologic diagnosis taken as the "gold standard." The sensitivity of frozen sections for the diagnosis of malignant neoplasm was 17%. The median number of vascular invasions was 1, identified with a mean number of 9 paraffin-blocks of the tumor. In most cases, intraoperative frozen sections are unable to establish the proof of malignant neoplasm. Intraoperative study of tumor differentiation is useful to select follicular tumors that require a rapid definitive diagnosis and a completion thyroidectomy within 48 to 72 hours (73% of the cases in our study).     

Follicular carcinoma

The workshop participants agreed on the following points regarding follicular carcinoma: Follicular carcinoma should be divided into two groups according to its degree of invasion: encapsulated and widely invasive. Patients in the first group only occasionally develop distant metastases, whereas in the second group the prognosis is much poorer. In encapsulated follicular tumors, high cellularity and nuclear atypia should not be used as criteria of malignancy; this diagnosis should be based on the presence of vascular or capsular invasion. Only tumor thrombi occurring in vessels in or outside the capsule should be regarded as indicative of vascular invasion. Capsular invasion should be diagnosed only if penetration of the whole capsule is seen. We agree that some tumor islands within the capsule may represent true tumor invasion, but we believe that some others may be due to capsular infoldings or tangential sectioning. Whenever tumor tissue within the capsule is seen, additional tissue blocks from the capsular area should be processed in a search for capsular penetration or vascular invasion. The degree of differentiation in follicular carcinoma does not correlate to the course of disease as clearly as the degree of invasion, although the so-called insular or poorly differentiated, subtype seems to have a poorer prognosis. Thyroid carcinomas composed of large eosinophilic cells (Hürthle cell carcinomas) usually show follicular differentiation and are therefore included in the category of follicular carcinoma. The same diagnostic criteria of malignancy that apply for other follicular tumors should be used when evaluating these tumors. Although follicular carcinomas often show foci of clear cells, tumors composed solely of clear cells are rare. Most pure clear-cell tumors in the thyroid represent metastatic tumors, usually from the kidney. In the distinction of follicular carcinoma from papillary carcinoma, all differential diagnostic criteria should be used. However, in some cases, the diagnosis can be based on one criterion only, mainly the presence of widespread ground-glass nuclei or abundant neoplastic papillae in papillary carcinoma. The presence of occasional papillae in encapsulated tumors composed of large eosinophilic cells is not sufficient for the diagnosis of papillary carcinoma if the other microscopic features of this tumor are lacking.     

Galectin-3, a marker of well-differentiated thyroid carcinoma, is expressed in thyroid nodules with cytological atypia

AIMS: The distribution of galectin-3, a widely recognized marker of well-differentiated thyroid carcinoma, was investigated in 95 thyroid lesions including nodules with foci of cytoarchitectural atypia. METHODS AND RESULTS: Twenty-eight papillary carcinomas, five follicular carcinomas, one Hurthle cell carcinoma, three poorly differentiated carcinomas, one anaplastic carcinoma, 25 nodular hyperplasias and 27 follicular adenomas, including nodules with atypical features, three neoplasms of undetermined malignant potential and two thyroiditis cases were examined. By immunohistochemistry, galectin-3 was consistently found in carcinomas; otherwise benign nodules exhibited galectin-3-positive clusters of cells with poorly developed features of differentiated carcinoma (mainly of papillary type) such as nuclear chromatin clearing, nuclear clefting, pseudoinclusions, which, in each case, were not histologically sufficient to warrant a definitive diagnosis of malignancy. In other nodules galectin-3 staining was negative. The latter were either clearly benign or showed constantly a minor degree of chromatin clearing and of other atypical features when compared with galectin-3-positive cases. CONCLUSIONS: Galectin-3, a reliable marker of differentiated thyroid carcinoma as confirmed in our series of malignant neoplasms, appears expressed in nodules with an overall benign appearance but with focal areas suspicious for malignancy. The significance of such findings needs to be further investigated.     

Galectin-3 does not reliably distinguish benign from malignant thyroid neoplasms

AIMS: To determine whether galectin-3 is a sensitive indicator of thyroid malignancy. It has been suggested as a potential marker for differentiating thyroid carcinoma from benign or non-neoplastic lesions in preoperative fine-needle aspirates (FNAs). METHODS: Galectin-3 protein expression was assessed by immunohistochemistry in formalin-fixed thyroid tissues from 124 patients with histological diagnoses of papillary carcinoma (n = 38), follicular carcinoma (n = 19), follicular adenoma (n = 32) and dominant nodules of multinodular goitre (n = 35). Expression of galectin-3 was also assessed by Western blotting in 24 fresh thyroid tissues. RESULTS: Galectin-3 expression was observed in the majority of carcinomas (papillary 92%; follicular 74%). However, a large proportion of follicular adenomas (72%) and multinodular goitres (57%) also expressed galectin-3. In addition, galectin-3 expression was observed in epithelial cells of normal thyroid tissue and Hashimoto's thyroiditis. Galectin-3 immunopositivity was significantly greater in papillary carcinomas than in dominant nodules or follicular adenomas (P < 0.0001, P = 0.0005, respectively). However, galectin-3 expression was no greater in follicular carcinomas than in follicular adenomas (P = 0.8735). Western blotting analysis confirmed both the specificity of the antiserum and expression of galectin-3 in multinodular goitres, follicular adenomas/carcinomas and papillary carcinomas. CONCLUSION: The data demonstrate that galectin-3 is not a reliable immunohistochemical marker to distinguish benign from malignant thyroid follicular lesions.     

Expression of cytokeratin 19, HBME-1 and galectin-3 in neoplastic and nonneoplastic thyroid lesions

In this study, 105 cases of thyroid lesions were evaluated to assess the role of HBME-1, cytokeratin-19 (CK-19), galectin-3 in distinguishing benign from malignant thyroid lesions. Thirty-seven papillary, 10 follicular, 6 medullary, 1 mixed medullary follicular cell carcinoma, 3 poorly differentiated carcinoma, 18 adenomatous nodular hyperplasia, 30 follicular adenoma cases were included in the study. Immunohistochemical staining was performed with HBME-1, CK-19, galectin-3 on cross-sections derived from selected paraffin blocks. Benign and malignant lesions were compared in terms of intensity, percentage and type of staining with CK-19, HBME-1 and galectin-3, and a statistically significant difference (p < 0.05) was found. The percentage and intensity of staining was higher in malignant lesions. Especially, strong and diffuse expressions of CK19, HBME-1 and galectin-3 were observed in papillary carcinomas. Membranous (luminal) staining was seen more frequently in malignant lesions; cytoplasmic staining in benign lesions. It was concluded that these markers could assist in the diagnosis of thyroid lesions with cellular properties suspicious for the diagnosis of papillary carcinoma and without capsule and vessel invasion. They may be used especially in cases where the follicular variant of papillary carcinoma, follicular adenoma and follicular carcinoma are confused with each other and follicular adenoma cannot be differentiated from follicular carcinoma.     

Differential expression of galectin-1 and galectin-3 in thyroid tumors. Potential diagnostic implications.

Carcinoma of the thyroid gland, the most frequently diagnosed endocrine malignancy, is often associated with early regional metastases. With the exception of papillary carcinoma, distinguishing benign from malignant thyroid neoplasms in the absence of metastatic disease is difficult. Recently, the vertebrate lectins galectin-1 and galectin-3 have been implicated in the regulation of cellular growth, differentiation, and malignant transformation of a variety of tissues. To determine whether these galectins have a role in thyroid neoplasia, we analyzed 32 specimens from thyroid malignancies (16 papillary, 7 follicular, 8 medullary carcinomas, and 1 metastasis to lymph node), 10 benign thyroid adenomas, 1 nodular goiter, and 33 specimens from adjacent normal thyroid tissue for the expression of galectin-1 and galectin-3 with immunohistochemical and immunoblotting techniques utilizing anti-galectin antibodies. All thyroid malignancies of epithelial origin (ie, papillary and follicular carcinomas) and a metastatic lymph node from a papillary carcinoma expressed high levels of both galectin-1 and galectin-3. The medullary thyroid carcinomas, which are of parafollicular C cell origin, showed a weaker and variable expression of these galectins. In contrast, neither benign thyroid adenomas nor adjacent normal thyroid tissue expressed galectin-1 or galectin-3. These results suggest that galectin-1 and galectin-3 may be associated with malignant transformation of thyroid epithelium and may potentially serve as markers for distinguishing benign thyroid adenomas from differentiated thyroid carcinomas.     

Immunohistochemical expression of HBME-1 and galectin-3 in the differential diagnosis of follicular-derived thyroid nodules

BackgroundThyroid nodules are common among adults with only a small percentage being malignant and histologically mimic benign nodules. Accurate diagnosis of these thyroid nodules is critical for the proper clinical management. The determination of malignancy in follicular patterned thyroid lesions is based on postoperative histological findings. Therefore, affected patients are referred for surgery, although only 10% will have a final diagnosis of malignancy. The aim of this study was to investigate the ability of two immunohistochemical (IHC) markers; galectin-3 and Hector Battifora mesothelial-1 (HBME-1) individually or in combination, to distinguish between benign (non-neoplastic and neoplastic) and malignant (follicular and papillary carcinomas) thyroid lesions removed by surgical resection.MethodsWe investigated the immunoexpression of galectin-3 and HBME-1 in 50 cases of benign and malignant thyroid nodules. The benign group included 13 cases of thyroid nodular goiter (NG) and 9 cases of follicular adenoma (FA). The malignant group included 5 cases of follicular thyroid carcinomas (FC), 18 cases of classic papillary thyroid carcinoma and 5 cases of follicular variant papillary carcinoma (FVPC).ResultsThe staining results showed that malignant tumors expressed galectin-3 and HBME-1 significantly more than benign nodules. The sensitivity of these markers for the distinction between benign and malignant lesions ranged from 89.3% to 92.9%. Co-expression of galectin-3 and HBME-1 was seen in 82.1% of carcinomas, but in none of the benign nodules. Immunoexpression was usually diffuse in malignant tumors, and focal in the benign lesions.ConclusionOur findings indicate that these immunohistochemical markers are significantly more expressed in malignant tumors compared to benign lesions and may be of additional diagnostic value when combined with routine histology. Galectin-3 has higher sensitivity and specificity of immunoexpression in thyroid malignancy than HBME-1, and the combined use of galectin-3 and HBME-1 can increase the specificity of immunoexpression in malignant tumors.     

Macrofollicular variant of follicular thyroid carcinoma: a clinical,cytologic, morphologic,and image analysis study of a unique case

Thyroid lesions composed of large follicles that contain abundant colloid are usually regarded as benign hyperplastic or adenomatous nodules both by fine-needle aspiration cytology and histology. In such cases, the pathologist is less likely to request a complete inclusion of the capsule into paraffin block and to look for vascular and/or capsular invasion, the only criteria that permit the differential diagnosis between a benign nodule and a follicular carcinoma. We report the first case of a follicular thyroid carcinoma composed predominantly (>90%) of macrofollicles with a surface area that was up to 5 times larger than the surface area of normal follicles, as calculated with an image analysis system. Capsular invasion was detected in 2 separate foci. The tumor was classified as a minimally invasive follicular carcinoma, macrofollicular variant. This case is detailed to highlight the potential pitfall that may arise from an incomplete histological analysis of a macrofollicular lesion, with particular attention paid to the differential diagnoses.     

Immunohistochemical expression of galectin-3 in benign and malignant thyroid lesions

CONTEXT: The expression of galectin-3, a human lectin, has been shown to be highly associated with malignant behavior of thyroid lesions. DESIGN: We studied the immunohistochemical expression pattern of galectin-3 in a variety of follicular-derived thyroid lesions (13 benign and 62 malignant), including Hürthle cell and follicular carcinoma, papillary carcinomas and variants, and anaplastic and poorly differentiated carcinomas. RESULTS: Immunoreactivity was strongest in papillary thyroid carcinomas, whereas staining was less intense in Hürthle cell and anaplastic carcinomas, and even weaker in the follicular variant of papillary thyroid carcinoma. Staining was absent or weak in the 3 follicular thyroid carcinomas and was negative in both insular carcinomas. In several tumors, staining was stronger at the advancing invasive edge of the lesion than in the central portion of the tumor. Galectin-3 was also expressed focally and weakly in reactive follicular epithelium and entrapped follicles in chronic lymphocytic thyroiditis. A variety of thyroid lesions showed prominent endogenous, biotin-like activity, which could cause flaws in interpretation if a biotin-detection system were used. CONCLUSION: We conclude that galectin-3 immunostaining, when used in biotin-free detection systems, may be useful as an adjunct to distinguish benign from malignant thyroid lesions.     

Late bone metastasis from an encapsulated follicular carcinoma of the thyroid withoutcapsular and vascular invasion

A unique case of encapsulated follicular carcinoma of the thyroid, which lacked histologic evidence of capsular and vascular Invasion but developed a late bone metastasis, is described. The thyroid tumor was found in a 42-year-old man. It was relatively small (2.5 cm) and totally encapsulated. Histologically, the thyroid tumor showed a microfollicular growth pattern of follicular cells and revealed no histologic evidence of nuclear atypia, mitotic figures or capsular and vascular invasion. The diagnosis of microfollicular adenoma was made and partial thyroidectomy was performed. Bone (rib) metastasis of the thyroid tumor developed 22 years after the thyroidectomy. The present case suggested that capsular and/or vascular invasion is not always sufficient for the diagnosis of encapsulated follicular carcinoma of the thyroid.     

Minimally invasive follicular thyroid carcinoma

Infiltration of the capsule, vascular invasion, and/or neoplastic extension into the adjacent parenchyma are regarded as prerequisites for the diagnosis of follicular carcinoma. In modern practice, most of these tumors fall into the category of follicular carcinoma, minimally invasive (FCMI) characterized by evidence of limited capsular or vascular invasion with an excellent long-term prognosis and a good patient outcome. Notwithstanding the wide acceptance of the diagnostic criteria established by the World Health Organization for the classification of follicular carcinomas in particular, they have been difficult to apply and have led to a great deal of confusion. This confusion is compounded when applied to "low-grade" or "minimally invasive" follicular carcinoma because of the poor reproducibility of the classification and the variable results reported in the literature. Our surgical colleagues face a similar lack of a standardized treatment for low-grade follicular carcinomas, which leads to unnecessary surgical treatment. Standardization of histologic criteria is necessary to promote confidence and uniformity in the therapeutic approach of these tumors. We believe that a FCMI is defined as an encapsulated follicular tumor (not papillary), with only small to medium vessel invasion within or immediately adjacent to the tumor capsule and/or up to full-thickness capsular transgression without accompanying extension into the thyroid parenchyma with intervening fibrosis. By using these criteria, patients can be managed with conservative surgical excision to yield an excellent long-term patient outcome.     

Utility of galectin 3 expression in thyroid aspirates as a diagnostic marker in differentiating benign from malignant thyroid neoplasms

Galectin-3 is a 31kD beta-galactoside binding lectin, which is known to be expressed in various neoplasms including thyroid tumors. This study was conducted to study the role of galectin-3 in differentiating benign from malignant thyroid nodules onfine needle aspirates (FNAC). Galectin-3 immuocytochemistry was performed in 70 cases with adequate smears. The cytology diagnosis of these cases was: papillary carcinoma (25), follicular neoplasm (16), adenomatous goiter (20), hyperplastic nodule (5), medullary carcinoma (5) and anaplastic carcinoma (1). Galectin-3 positivity was seen in 80% of papillary carcinomas, 37.5% offollicular neoplasms and in 60% of benign nodules. The single case of anaplastic carcinoma was positive but all the cases of medullary carcinoma were negativefor galectin-3. Three of thefollicular neoplasms that were diagnosed on histology as carcinoma were positive on cytology and one case offollicular adenoma was also positive. Our study shows that galectin-3 is strongly expressed in smears of papillary carcinoma. However, since it is also expressed in a variety of benign lesions, its role as a pre-surgical markerfor differentiating benignfrom malignant thyroid nodules is limited.     

Diagnostic value of galectin-3, HBME-1, cytokeratin 19, high molecular weight cytokeratin, cyclin D1 and p27(kip1) in the differential diagnosis of thyroid nodules

The distinction between benign and malignant thyroid tumors is critical for the management of patients with thyroid nodules. We applied immunohistochemical staining for galectin-3, HBME-1, cytokeratin 19 (CK19), high molecular weight cytokeratin (HMWCK), cyclin D1 and p27(kip1) in 295 thyroid lesions to determine their diagnostic accuracy. The expression of all markers was significantly associated with differentiated thyroid carcinoma (DTC).The sensitivity for the diagnosis of DTC was 94.7% with galectin-3, 91.3% with HBME-1, and 90.3% with CK19. The specificities of these markers were 95.5%, 69.7%, and 83.1%, respectively. Combining these markers, co-expression of galectin-3 and CK19 or galectin-3 and HBME-1 was seen in 93.2% of carcinomas but in none of the benign nodules. Comparing follicular variant of papillary carcinoma (FVPC) with follicular carcinoma (FC), the expression of galectin-3, CK19, and HMWCK was significantly higher in FVPC. When comparing FC with FA, the expression of galectin-3 and HBME-1 was significantly higher in FC. These results suggest that 1) galectin-3 is a useful marker in the distinction between benign and malignant thyroid tumors, 2) the combined use of HBME-1 and CK19 can increase the diagnostic accuracy, and 3) the use of CK19 and HMWCK can aid in the differential diagnosis between PC and FC.     

Galectin-3 in differential diagnosis and prognosis of follicular tumors of the thyroid gland

Differential diagnosis between follicular thyroid tumours (FTT) is difficult both at cytological and histological levels. Infiltrative growth is authentic criterion of malignancy. Immunohistochemical reaction (PAP-method) with galectin-3 antibodies was used. The results allow to make differential diagnosis of thyroid tumours before the surgery. Immunohistochemical identification of galectin-3 in the tissue of follicular adenomas with grave dysplasia and follicular carcinoma is an unfavourable prognostic sign.