[Low galectin-3 capacity to discriminate thyroid lesions].

Unlabelled: Galectin-3 is considered useful in identifying lesions included in the term follicular tumour.

Objective: To evaluate galectin-3's power to discriminate among diverse thyroid lesions and to identify a set point of expression at which there is the least possible false positive results.

Methods: 26 follicular carcinomas and 104 assorted thyroid lesions were analysed (8 Hashimoto's thyroiditis, 18 goiter, 44 adenoma, 27 papillary carcinoma and 7 normal glands). Immunohistochemistry for galectin-3 was performed way (NCL-GAL-3, 1:100, Novocastra, UK). In a blinded manner intensity and percentage of expression were evaluated, as was its capacity to identify the previously mentioned thyroid entities with 2 x 2 tables. Minimum reactivity set point values were identified and the one which presented the least false positive cases was selected.

Results: A reaction was considered positive when 25% of the cells were marked, in which case neither the Hashimoto's thyroiditis, goiter, nor the residual tissue were positive for galectin-3. A positive galectin-3 reaction was identified in 4/44 adenomas, 5/26 follicular carcinomas and 18/27 papillary carcinomas. From a total of 53 carcinomas, 23 showed positive and 30 a negative reaction to galectin-3. Thus, galectin-3's sensitivity to discriminate between benign and malignant lesions was 94% while its specificity was 43%. When comparing follicular carcinoma with adenoma, sensibility was 19% while specificity was 91%. The positive predictive value was 56% and the negative predictive value 66%. Galectin-3 was most useful for identifying papillary thyroid carcinoma.

Conclusions: Galectin-3 has limited value to distinguish benign from malignant thyroid lesions. The reaction must be considered positive when at least 25% of cells are marked.