Should cytopathologists stop reporting follicular neoplasms on fine-needle aspiration of the thyroid? Diagnosis and histologic follow-up of 147 cases

BACKGROUND. As the consequence of the decreasing incidence of follicular thyroid carcinoma (FC), one wonders whether cytopathologists should stop reporting follicular neoplasms in fine-needle aspiration (FNA) of the thyroid to minimize unnecessary thyroidectomies, if the follicular variant of papillary carcinoma (FVPC) has been excluded. METHODS. Over a 6-year-period, 2667 ultrasound-guided FNAs of the thyroid were performed at our practice. A total of 246 nodules (9.2%) were reported as follicular neoplasms, using abundant blood as the diagnostic clue. All FNA specimens were prepared and reported by one cytopathologist and the final pathology was reported by surgical pathologists in various hospitals in New York City. RESULTS. The histologic follow-up was available for 147 cases and showed 5 cases of widely invasive FC (3.4%), 10 cases of minimally invasive FC (6.8%), 8 cases of FVPC (5.4%), 92 cases of follicular adenoma (62.6%), and 32 cases of nonneoplastic nodules (21.8%). CONCLUSIONS. FVPC cannot be excluded completely from follicular neoplasms by FNA because, of the patchy distribution of papillary carcinoma nuclei in the encapsulated variant. Widely invasive FC still exists and may cause considerable morbidity in patients as young as the third decade of life. It is the opinion of the authors that cytopathologists should continue reporting follicular neoplasms in FNA of the thyroid. Cancer (Cancer Cytopathol) 2003;99:69-74. (C) 2003 American Cancer Society.