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BACKGROUND: Galectin-3, a lectin with specificity for beta galactosides, is believed to be implicated in multiple biological processes through interactions with complementary glycoconjugates. Alterations in galectin-3 expression are observed in a variety of human tumors. In thyroid, this lectin has been found to be highly expressed in malignancies of epithelial origin. We analyzed galectin-3 expression in medullary thyroid carcinoma (MTC). MATERIALS AND METHODS: An immunohistochemical study using monoclonal antibody was performed on paraffin sections of twenty cases of sporadic MTC comprising ten cases without and ten cases with lymph node metastases at the time of surgery. RESULTS: Positive cytoplasmic staining for galectin-3 was found in 16/20 cases, but varied in intensity and distribution from weak/focal (7/16) to moderate (7/16) or strong (2/16). Advanced stage of MTC (with lymph node metastases at the time of surgery) showed moderate to strong galectin-3 expression more frequently (8/10) than cases without lymph node metastases (1/10). CONCLUSION: These findings suggest that galectin-3 expression is associated with the advanced stage of disease and that this lection might play a role in the pathobiology of MTC.

Thyroid-specific malignant tumors are derived from follicle cells (papillary and follicular carcinoma), and from parafollicular, calcitonin-producing C-cells (medullary carcinoma). The main criterion for diagnosis of papillary carcinoma is the occurrence of ground glass, hypochromic nuclei, often associated with papillae as the prominent pattern of the tumor, and psammoma bodies. The diagnosis of follicular carcinoma is based on the true infiltration of the venous vessels outside the tumor capsule and the fungus-like infiltration through the tumor capsule into the surrounding parenchyma. Anaplastic carcinoma is mostly detected by the pathologist by fine-needle aspiration biopsy, or tumor reduction specimen. Medullary thyroid carcinoma is typically composed of solid nests and infiltrating formations of polygonal or spindle-shaped cells and amyloid deposits within the stroma of the tumor. Two main discriminatory immunohistochemical markers for tumors with follicular and parafollicular origin are thyroglobulin and calcitonin, respectively. Thyroglobulin is present in more than 95% of papillary and follicular carcinomas, whereas anaplastic thyroid carcinomas are mostly immunonegative for thyroglobulin. Medullary carcinoma is characteristically positive for calcitonin, pan-neuroendocrine markers, and often numerous peptides.

Background: Secondary thyroid cancer is much less frequent than primary and in the majority of cases represents disseminated disease where operation on thyroid is useless or thyroid tumor is not operable, infiltrating surrounding structures. Methods: Five case reports of patients operated for secondary thyroid cancer. Results: Case 1: In male patient aged 64 years thyroidectomy was done for thyroid solid tumor 5 years after lung lobectomy for bronchogenic planocellular cancer. FNB suspected nonthyroid cancer histological analysis revealed planocellular cancer (Grimelius staining excluded medullar cancer) and multinodular goiter. Case 2: In female patient aged 65 years, thyroidectomy was done 4 years after left mastectomy with the history of long standing multinodular toxic goiter. Infiltrate remained in trachea and esophagus, histology revealed breast cancer metastasis in thyroid, confirmed with special mucin I, and estrogen receptor staining with negative thyroglobulin staining. Case 3: In female patient aged 76 years thyroidectomy was performed for metastatic lucidocellular kidney cancer in recurrent goiter (with Vimentin staining), a year after nephrectomy and 50 years after first goiter operation. Case 4: In female patient aged 58 years thyroidectomy was performed for planocellular infiltration of esophagus into the left thyroid lobe. Case 5: In female patient aged 77 years thyroidectomy was done for hemorrhage into thyrotoxic goiter, histology revealed metastasis of planocellular cancer of unknown origin into thyroid. Case 6: In male patient aged 54 years, thyroidectomy was done for thyroid metastatic lucidocellular cancer of kidney, 2 years after nephrectomy. Conclusion: Although prognosis of secondary thyroid cancer is poor, in rare cases aggressive surgery with adjuvant therapy may be successful.

Background: Galectin-3 is an endogenous beta-galactoside binding lectin implicated in neoplastic transformation and tumor progression. High levels of this lectin have recently been found in malignant thyroid tumors, but not in normal or benign thyroid tissue, suggesting galectin-3 as a promising presurgical marker of thyroid malignancy. Methods: We analyzed immunohistochemically galectin-3 expression in thyroid tissue using a monoclonal antibody. The total of 108 tissue specimens included 55 cases of thyroid carcinoma (30 papillary, 15 follicular, and 10 anaplastic type), 15 samples of follicular adenoma, 15 samples of normal thyroid tissue, and 23 thyroid tissue specimens from human fetuses (16 to 37 weeks of intrauterine life). Results: The results showed galectin-3 expression in 20/30 papillary carcinomas, 11/15 follicular carcinomas, 10/10 anaplastic carcinomas, and 4/15 follicular adenomas. Thyroid follicular cells in normal adult and fetal tissue were negative. Conclusions: These results further confirm that galectin-3 expression is a feature of malignant thyroid cells, and that immunohistochemical detection of galectin-3 could be useful in thyroid carcinoma diagnostics. The absence of galectin-3 in thyroid cells during fetal development suggests that galectin-3 is expressed de novo during malignant transformation of thyroid epithelium, thus it should not be considered an oncofetal antigen.