Diagnostic accuracy of CNB in tyroid nodules smaller than 1 centimeter

Miguel Paja; Aitziber Ugalde; Igone Korta; Rosa Zabala; Adela L Martinez; Alba Zabalegui; Cristina Arrizabalaga; Laura A Calles; Eider Etxebarria; Cura Jose L Del

doi:10.1530/endoabs.56.P1156

Current guidelines suggest sonographic follow-up in thyroid nodules smaller than 10 mm with intermediate or highly suspicious features as ultrasound-guided FNAC has poor results in these nodules, and the risk of non-diagnosed thyroid carcinoma is very low. CNB has proved superior to repeated FNAC in case of insufficient or indeterminate first FNAC.

Objective: Evaluate diagnostic accuracy of CNB in nodules smaller than 10 mm with intermediate or high suspicious ultrasound (US) features.

Methods: Retrospective evaluation of all nodules CNB performed to thyroid nodules smaller than 1 cm in a tertiary center between 2006 and 2015. Evaluation included demographic data, US features, histological result, and surgical result when operated.

Results: CNB on 245 nodules, all with suspicious features on US, were included: size 3–9 mm (41 of them ≤5 mm); 230 solid; 88.6% in women; 166 (67.8%) in multinodular goiters, 89 of them with simultaneous CNB in a different nodule. Histological study showed: 11 insufficient samples (4.5%); 176 benign (71.8%, 26 inflammatory); 12 follicular proliferation (4.9%, 3 of them oxyphilic), and 46 malignant (18.8%, one medullary thyroid cancer and 45 papillary thyroid cancer, PTC). All non-operated nodules with insufficient or benign CNB and three with follicular proliferation were controlled 2–10 years after first CNB, 7 of them with a second benign CNB, and there was not US changes in this period. On surgery, all cases of malignant diagnosis were confirmed, 1 PTC was diagnosed among 9 resected nodules with diagnosis of follicular proliferation on CNB and 2 PTC were diagnosed among 19 resected nodules with benign CNB. The false negatives were one case of painful Hashimoto’s disease that required surgery in which CNB missed the target, and a case that was operated by other nodule with follicular proliferation in the same gland in which the CNB showed subtle atypia but was not enough to diagnose malignancy. Sensitivity to detect malignancy was 95.9% and positive predictive value 79.7%. Specificity was 94% and negative predictive value was 98.9%. C- CNB may be a useful and feasible technique to study suspicious thyroid nodules smaller than 10 mm. This technique shows high sensitivity and PPV to detect malignancy and very high specificity and NPV, making follow-up unnecessary in most of cases.

Endocrine Abstracts

P1156