Randomized prospective evaluation of frozen-section analysis for follicular neoplasms of the thyroid

Abstract

Objective: To evaluate the clinical utility of frozen section in patients with follicular neoplasms of the thyroid in a randomized prospective trial.

Summary background data: The finding of a follicular neoplasm on fine-needle aspiration prompts many surgeons to perform intraoperative frozen section during thyroid lobectomy. However, the focal distribution of key diagnostic features of malignancy contributes to a high rate of noninformative frozen sections.

Methods: The series comprised 68 consecutive patients with a solitary thyroid nodule in whom fine-needle aspiration showed a follicular neoplasm. Patients were excluded for bilateral or nodal disease, extrathyroidal extension, or a definitive fine-needle aspiration diagnosis. Final pathologic findings were compared with frozen sections, and cost analyses were performed.

Results: Sixty-one patients met the inclusion criteria. Twenty-nine were randomized to the frozen-section group and 32 to the non-frozen-section group. In the non-frozen-section group, one patient was excluded when gross examination of the specimen was suggestive of malignancy and a directed frozen section was diagnostic of follicular carcinoma. Frozen-section analysis rendered a definitive diagnosis of malignancy in 1 of 29 (3.4%) patients, who then underwent a one-stage total thyroidectomy. In the remaining 28 patients, frozen section showed a "follicular or Hürthle cell neoplasm." Permanent histology demonstrated well-differentiated thyroid cancer in 6 of these 28 patients (21%). Of the 31 patients in the non-frozen-section group, 3 (10%) showed well-differentiated thyroid carcinoma on permanent histology. Complications were limited to one transient unilateral vocal cord dysfunction. All but one patient had a 1-day hospital stay. There were no significant differences between the groups in surgical time or total hospital charges; however, the charge per informative frozen section was approximately $12,470.

Conclusions: For the vast majority of patients (96.4%) with follicular neoplasms of the thyroid, frozen section is neither informative nor cost-effective.

Figures

Figure 1. Randomization scheme.

Figure 2. Frozen section showing an invasive tumor (T) filling a large-caliber vascular lumen (L). The vascular endothelial lining is indicated by the arrows.

Figure 3. Comparison of frozen-section and permanent-section histopathology in a case of a follicular variant of papillary carcinoma. The frozen section is shown in A (low power) and B (high power). In the frozen section, the diagnostic features of malignancy cannot be appreciated. Specifically, there is no infiltration of the surrounding capsule, papillary formations are absent, and the nuclear atypia of papillary carcinoma are not well developed. The permanent section is shown in C (low power) and D (high power). In this well-fixed tissue, the characteristic nuclear features of papillary carcinoma (nuclear enlargement, optic clearing and crowding) are much easier to appreciate.