Objective: To evaluate the performance of core-needle biopsy (CNB) in thyroid using a cohort of patients in which it was used as first choice.
Methods: Our institutional review board approved this retrospective study. We reviewed all CNB performed in our center over a period of 11 years. Ultrasound-guided CNBs were performed using a spring-loaded 18-gauge biopsy needle. We used a classification with four diagnostic categories for CNB results: insufficient, benign, follicular lesion (indeterminate), and malignant. Final diagnosis was based on surgical diagnosis or follow-up of at least 2 years in non-operated patients.
Results: The study included 4412 CNB in 4112 nodules of 3768 patients, 300 of them repeated biopsies. Results were 148 insufficient (3.4%), 3706 benign (84%), 278 follicular lesions (6.3%), and 280 malignant (6.3%). Considering follicular lesion and malignancy CNB results as positive (both lead to the recommendation of surgery) sensitivity was 96% (CI 93.2-97.8) and specificity 93.7% (CI 92.9-94.5). Predictive positive value for a follicular lesion diagnosis was 12.2% and for a malignancy diagnosis, 98.6%. CNB likelihood ratio for malignancy of a malignant diagnosis was 841.9 (CI 315.8-2313.3), of a malignant/follicular lesion diagnosis was 23.4 (CI 20.1-27.3), and of a benign diagnosis was 0.04 (CI 0.02-0.07). Repeated CNB in 53 insufficient biopsies obtained 50 diagnostic results. Minor complications occurred in 2.2% of CNB, and major in four procedures (0.09%).
Conclusions: CNB in thyroid nodules is accurate and has few complications and a low rate of non-diagnostic and indeterminate diagnoses. It can be an alternative method when FNAC has poor performance. Repeating biopsy is useful after non-diagnostic biopsies.
Key points: • Core-needle biopsy of thyroid has a low ratio non-diagnostic and indeterminate results. • Core-needle biopsy results are highly reliable, especially benign results. • Complication rate of core-needle biopsy of thyroid is low.
Keywords: Core-needle biopsy; Fine-needle aspiration; Thyroid carcinoma; Thyroid nodule; Ultrasound.