Papillary carcinoma of the thyroid: can operative management be based solely on fine-needle aspiration?

BACKGROUND: Fine-needle aspiration cytology is sensitive for detecting malignancies such as papillary carcinoma of the thyroid gland. Because fine-needle aspiration specificity for papillary carcinoma of the thyroid is variable, routine intraoperative frozen section is often advocated. STUDY
DESIGN: To define the roles of fine-needle aspiration and frozen section in papillary carcinoma of the thyroid gland, we reviewed data from 82 patients who underwent thyroidectomy between August 1989 and August 1995 for papillary carcinoma of the thyroid cytology. Results of fine-needle aspirations were grouped into three categories: diagnostic of papillary carcinoma of the thyroid; diagnostic of follicular-variant of papillary carcinoma of the thyroid; or suspicious for papillary carcinoma of the thyroid. Definitive diagnoses were made on permanent histology.
RESULTS: A fine-needle aspiration revealing papillary carcinoma of the thyroid was 98 percent specific for cancer or 100 percent specific for follicular-variant of papillary carcinoma of the thyroid. A fine-needle aspiration that was suspicious for papillary carcinoma of the thyroid (n = 24) was only 54 percent specific for cancer. On the basis of gross intraoperative findings, 5 of these 24 patients underwent total thyroidectomy without frozen section, and all had carcinoma. The other 19 had frozen section analysis. Of the 5 patients with cancer detected by frozen section, 4 had cancer on permanent histology. Findings on frozen section demonstrated a follicular neoplasm in the other 14 patients, of which 4 ultimately were cancer.
CONCLUSIONS: When papillary carcinoma of the thyroid or follicular-variant of papillary carcinoma of the thyroid is definitively diagnosed on fine-needle aspiration, the surgeon can perform definitive thyroidectomy without frozen section because of the high specificity for cancer. If the fine-needle aspiration is suspicious for papillary carcinoma of the thyroid, the incidence of cancer is 54 percent, and patients with these conditions should undergo surgery with frozen section. When either gross findings or frozen sections suggest malignancy, definitive thyroidectomy can be performed because 90 percent of such cases will be cancer. If frozen section is not diagnostic of malignancy, a thyroid lobectomy/isthmusectomy is recommended because 71 percent have a benign lesion. This systematic approach to papillary carcinoma of the thyroid will obviate unnecessary frozen sections while maintaining excellent diagnostic specificity.