No abstract

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.

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.

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.

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.