Hemosiderin laden macrophages and hemosiderin within follicular cells distinguish benign follicular lesions from follicular neoplasms.

Background: Published criteria to distinguish benign colloid nodules from follicular neoplasms emphasize only three interdependent features: size of follicles, amount of colloid, and cellularity. There is a need for the validation of other independent criteria. Methods: This study quantified the significance of cystic change, defined as presence of macrophages, and the presence of hemosiderin in either the macrophages or follicular cells. The cohort consisted of 165 patients with fine needle aspiration (FNA) and histologic follow-up of either goiter (101), follicular adenoma (47), or follicular carcinoma (17). Papillary thyroid carcinomas and Hurthle cell neoplasms were excluded from the cohort, because these categories are known to show cystic change and hemosiderin. FNAs were reviewed blindly with the most cellular slide scored for the presence of macrophages and/or hemosiderin. Results: Hemosiderin within macrophages were seen in 67% (68 of 101) of the goiters and only 6% (four of 64) of follicular neoplasms ( P P P Conclusions: If papillary thyroid carcinoma and Hurthle cell neoplasm are ruled out, our findings indicate that the presence of hemosiderin virtually excludes a clinically significant follicular neoplasm.