Should cytopathologists stop reporting follicular neoplasms on fine-needle aspiration of the thyroid?

Abstract

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. © 2003 American Cancer Society.

Fine-needle aspiration of thyroid nodules: A study of 4703 patients with histologic and clinical correlations

“…43,44 The prevalence of malignancy in this category reportedly ranges from 20% to 60% in the literature. 12,24,27,45,46 In the current study, 326 patients (63%) in this category underwent surgery. Among them, 105 patients (32%) had malignant tumors (most were FVPCT).…”

“…Because of their cytomorphologic similarities, distinguishing between hyperplastic (adenomatous) nodule and FN sometimes is difficult and has been the subject of many studies. [23][24][25][26][27][28] Cytologically, it is almost unfeasible to differentiate hyperplastic nodule from so-called macrofollicular adenoma or simple adenoma. We do not consider this a discrepancy, because it probably would not harm patients.…”

Efficacy and Pitfalls of FNAC of Thyroid Lesions in Children and Adolescents

“…Yang et al, [4] suggested that, the most important clue in differentiating follicular neoplasm from nodular hyperplasia was the presence of abundant blood containing microfollicles in the follicular neoplasm [22]. However, macrofollicular adenomas have far lower microvessel density than microfollicular nodules because the space occupied by the large colloid lakes are devoid of blood vessels.…”

Human Telomerase Reverse Transcriptase Gene Expression and the Surgical Management of Suspicious Thyroid Tumors

“…Although the cytopathologic assessment of thyroid FNAs has proven to be an excellent predictor of malignancy when the verdict is clearly benign or malignant, there remains a substantial subset of cases in which the FNA is inconclusive. These include FNAs with findings suspicious but not diagnostic of malignancy, or suggesting a follicular neoplasm, which does not distinguish benign from malignant tumors (3)(4)(5)(6)(7). Not only is an indeterminate FNA result uninformative in the management of suspicious thyroid nodules, but intraoperative frozen section is often unhelpful in the distinction of benign from malignant lesions as well (8 -14).…”