Evaluation of HBME-1 immunostaining in fine needle aspiration cytology of thyroid nodules

Summary HBME-1 antibody has been evaluated as a differentiating marker between mesothelioma and various adenocarcinomas in body cavity fluid. We studied the diagnostic utility of HBME-1 antibody in thyroid nodules in FNA smears. We examined the reactivities with HBME-1 68 cases of the thyroid carcinoma (51 papillary carcinoma, 15 follicular carcinoma, 2 anaplastic carcinoma), 25 cases of follicular adenoma and 25 cases of adenomatous goiter. Smears were fixed 95% ethyl alcohol and immunostaining by the LSAB method. The cell membrane and cytoplasm were strongly positive for HBME-1 in all papillary (51/51) and follicular carcinoma (73%, 11/15). Follicular adenomas (16%, 4/25) were focally positive in cell membrane. In contrast, anaplastic carcinoma and adenomatous goiter were all negative. HBME-1 indicated a high positive rate with thyroid carcinoma (sensitivity of 91% and specificity of 100%). We conclude that HBME-1 immunostaining may be helpful for the cytological differential diagnosis between benign lesions and differentiated thyroid carcinoma.