HASHIMOTOS-THYROIDITIS - CYTODIAGNOSTIC ACCURACY AND PITFALLS

To determine the cytodiagnostic accuracy rate and pitfalls of Hashimot o's thyroiditis (HT), the files and smears prepared from the thyroid n eedle aspirates of 146 patients with suspected HT and/or clinically an d serologically confirmed HT were reviewed. Of those patients, 105 pre sented with a diffuse and rubbery thyroid enlargement, and 41 with one or two prominent nodules. For the first group (105 patients), the nee dle aspiration biopsy (NAB) was performed on one or two thyroid lobes during their initial endocrinologic consultation, and for the second g roup (41 patients), the NAB was performed on and around the predominan t nodules that were found either at initial physical examination or du ring the patients' routine follow-ups. In 134 cases, a cytodiagnosis o f HT was made on the first NAB. Among the 41 patients with a prominent thyroid nodule, a thyroid neoplasm was suspected clinically in four b ecause their thyroid nodules increased in size. In the other 12 patien ts, a cytodiagnosis of follicular neoplasm (FN) was made in five cases , and a Hurthle cell tumor (HCT) was diagnosed or suspected in seven p atients. All 16 patients had thyroid surgery, and a HT was histologica lly confirmed in all cases. In the first four patients, no tumor was f ound. Among five patients with a cytodiagnosis of FN, one had a hyperp lastic follicular cell nodule (HFCN), two had follicular adenomas, and two had papillary carcinomas of follicular variant For the seven pati ents with a cytodiagnosis of HCT, HCT was confirmed in three, three we re found to have hyperplastic Hurthle cell nodules (HHCN), and one sho wed a benign colloid nodule with Hurthle cell changes and remote hemor rhagic necrosis. It is concluded that NAB is highly sensitive in diagn osing HT with a diagnostic accuracy rate of 92% by the first biopsy at tempt. The cytologic differential diagnosis between an HFCN and a foll icular neoplasm and between an HHCN and apr HCT is impossible in some cases. (C) 1997 Wiley-Liss, Inc.