Thyroid fine-needle aspiration cytology: performance data of neoplastic and malignant cases as identified from 1558 responses in the ASCP Non-GYN Assessment program thyroid fine-needle performance data.

BACKGROUND: Fine-needle aspiration of the thyroid is a common procedure, with an established role in reducing unnecessary thyroid surgery and identifying neoplasms and malignancies.

METHODS: The study evaluated 1558 responses in the American Society for Clinical Pathology (ASCP) Non-GYN Assessment program of aspirates of thyroid neoplasms and malignancies and placed them into the following groups: group A (target or correct interpretation), group B (incorrect interpretation as a benign thyroid nodule), group C (incorrect interpretation malignant aspirate as thyroid neoplasm), and group D (malignant diagnosis with incorrect interpretation). In clinical practice, responses in groups A, C, and D would lead to surgical excision, whereas responses in group B would not.

RESULTS: Of a total of 1558 responses, 78.5% of the responses were in group A, 8.5% in group B, 3.75% in group C, and 9.25% in group D. By individual diagnosis, the group rates were 86.5%, 0%, 11%, and 2.5% for anaplastic thyroid carcinoma; 83%, 5.5%, 4.25%, and 7.25% for papillary thyroid carcinoma; 79%, 7%, 6%, and 8% for medullary thyroid carcinoma; 83.5% 6.75%, 0%, and 9.75% for Hürthle cell neoplasm; and 61%, 22%, 0%, and 17% for follicular neoplasm in groups A, B, C, and D respectively.

CONCLUSIONS: Fine-needle aspiration was effective in diagnosing thyroid neoplasms and malignancies and in separating thyroid nodules into surgical and nonsurgical categories. Data from a large group of cytology professionals showed good performance; however, there is room for improvement, especially in making specific diagnoses. In particular, follicular neoplasm and follicular variant of papillary thyroid carcinoma were challenging diagnoses for participants.