INCIDENCE OF NEOPLASIA IN HASHIMOTOS-THYROIDITIS - A FINE-NEEDLE ASPIRATION STUDY

There is a recognized association between Hashimoto's thyroiditis (HT) and thyroid neoplasms. We reviewed fine-needle aspirations (FNAs) fro m 90 patients with HT to assess the contribution of this procedure. Fo r seven patients FNA showed HT and follicular neoplasm (n = 6) or HT a nd papillary carcinoma (n = 1). Eighteen patients underwent thyroid re section. Three patients had follicular adenomas which were not detecte d by FNA, one patient had papillary carcinoma confirmed, and six patie nts with follicular neoplasm by FNA were negative for tumor. Thus, 4% of our patients had confirmed neoplasms, an incidence lower than usual ly reported. One reason for the lower rate of neoplasia in our series was misinterpretation of follicular neoplasia in the background of HT. The cytologic changes in the hyperplastic follicular and metaplastic oncocytic epithelium are similar to those seen in follicular neoplasm. Our study suggests that these processes may be indistinguishable, and thus, in the presence of HT, the diagnosis of follicular neoplasm pro bably should not be rendered. (C) 1996 Wiley-Liss, Inc.