IMMUNOHISTOCHEMICAL ANALYSIS OF THYROID ADENOMAS WITH HURTHLE CELLS

Twenty-five cases of thyroid adenomas with Hurthle cell changes, both pure and focal, were studied histologically and immunohistochemically with two objectives: first to elucidate the relationship between the n ormal uninvolved thyroid and the adenoma; and second, to evaluate the role of immunohistochemical studies in adenomas with Hurthle cell chan ges. Representative sections were stained with a panel of nine antibod ies directed against thyroglobulin (TG), high molecular weight keratin (HMK)I low molecular weight keratin (LMK), p53, bcl-2, epithelial mem brane antigen (EMA), S100, carcinoembryonic antigen (CEA) and HMB45. I n all cases, uniform strong positive staining (+ + +)with TG and bcl-2 was seen in the normal thyroid tissue while the adenoma stained moder ately positive (+;). The reverse pattern was observed with LMK stainin g, Non-adenomatous thyroid cells were p53-negative, the majority of th e Hurthle cells, however, were p53-positive and adenomas with an incre ased number of Hurthle cells had an increased percentage of p53 staini ng. The expression of EMA was variable. All thyroid cells both outside and within the adenoma were S100-, CEA-4 and HMB45-negative in all ca ses, The exact significance of p53 overexpression in the Hurthle cells needs further evaluation.