Trefoil Factor 3 Immunohistochemical Characterization of Follicular Thyroid Lesions From Tissue Microarray

Objectives: To characterize trefoil factor 3 (TFF3) expressioninnormalthyroidtissuesamplescomparedwith that in follicular adenoma, follicular carcinoma, and follicular variant of papillary thyroid carcinoma using immunohistochemistry on tissue microarrays. Design:Immunohistochemicalanalysisof83normalthyroid tissue and of 83 follicular neoplasms (26 follicular adenomas, 25 follicular variant of papillary thyroid carcinoma, 23 follicular thyroid carcinomas, and 9 papillary thyroid carcinomas) was performed using an antibody to TFF3 on tissue microarray sections composed of formalin-fixed, paraffin-embedded tissue samples. Setting: Academic research. Patients: Thyroid tissue samples collected from patients over a 15-year period were obtained from the University of North Carolina Hospitals Division of Surgical Pathology archives. Main Outcome Measures:Thyroid tissue samples were gradedbyapathologistbasedonintensityofantibodystainingandonpercentageofcellsstained.LocalizationofTFF3 antibody was noted. Data were analyzed for semiquantitativedifferencesinimmunohistochemicalintensityofantibody staining and in percentage of cells stained among normal thyroid tissue samples, follicular adenoma, follicularthyroidcarcinoma,follicularvariantofpapillarythyroid carcinoma, and papillary thyroid carcinoma. Results:Semiquantitativeanalysisdemonstratedthatimmunohistochemistry detects significant levels of TFF3 expression in normal thyroid tissue samples compared with that in follicular lesions based on intensity of antibody staining (P.05). Only follicular thyroid carcinoma demonstrated a significant reduction in percent