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Objective: Fine-needle aspiration (FNA) and frozen section (FS) have been widely reported in the literature as having high sensitivity in the diagnosis of papillary carcinoma. With the increased recognition of the follicular variant of papillary thyroid carcinoma (FVPTC), several reports have pointed out the difficulty in diagnosing this variant of papillary carcinoma owing to its overlapping cytomorphological features with benign and malignant follicular lesions. We undertook this study to determine the sensitivity of FNA and FS in the diagnosis of FVPTC. Methods: Retrospective review of patients who underwent thyroidectomy from June 1994 to June 1999. Of the 63 patients found with a final pathological diagnosis of papillary thyroid carcinoma, only 47 had an adequate FNA and FS and were included in the study. These patients were divided into two groups, the usual type (n ‫؍‬ 23) and the follicular variant (n ‫؍‬ 24) of papillary carcinoma. Sensitivities of FNA and FS for these two groups of papillary carcinoma were then determined. Results: The sensitivity of the FNA was 25% and of the FS was 29% for the follicular variant of papillary thyroid carcinoma. This is in contrast to the sensitivity of FNA and FS for the usual papillary carcinoma, which were 74% and 87%, respectively. Conclusion: FNA and FS have low sensitivity in the diagnosis of the FVPTC. High degree of suspicion may increase the accuracy in the diagnosis of this variant of papillary carcinoma before or during surgery. However, the thyroid surgeon needs to realize that, like follicular carcinoma, FVPTC is often diagnosed only on final pathological examination. Key Words: Papillary carcinoma, follicular variant of papillary carcinoma, fine-needle aspiration, frozen section.

Of the 82 patients in this study, only one extra case of malignancy would be missed by elimination of the routine use of intraoperative frozen section. The authors conclude that the routine use of intraoperative frozen section may be unnecessary. The use of an adequate preoperative FNA together with sound clinical judgment at time of surgery can adequately guide the extent of surgical resection.

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Hürthle cell predominant thyroid nodules often confound the diagnostic utility of fine needle aspiration biopsy (FNAB) with cytology often interpreted as a Hürthle cell lesion with an indeterminate risk of malignancy, Bethesda category (BC) III or IV. Molecular diagnostics for Hürthle cell predominant nodules has also been disappointing in further defining the risk of malignancy. We present a case of a slowly enlarging nodule within a goiter initially reported as benign on FNAB, BC II but on subsequent FNAB suspicious for a Hürthle cell neoplasm, BC IV. The patient had initially requested a diagnostic lobectomy for a definitive diagnosis despite a higher risk of malignancy based on the size of the nodule > 4 cm alone. To better tailor this patient's treatment plan, a newer expanded gene mutation panel, ThyroSeq® v3 that includes copy number alterations (CNAs) and was recently found to have greater positive predictive value (PPV) for identifying Hürthle cell carcinoma (HCC), was performed on the FNAB material. Molecular profiling with ThyroSeq® v3 was able to predict a greater risk of carcinoma, making a more convincing argument in favor of total thyroidectomy. Surgical pathology confirmed a Hürthle cell carcinoma with 5 foci of angioinvasion and foci of capsular invasion.