Endocrine Abstracts

Introduction: Fine-needle aspiration cytology (FNAC) of thyroid nodules can be associated with non-diagnostic (ND) results, despite the usage of ultrasound (US) guidance. It is recommended to repeat the FNAC because of the possible risk of malignancy in these nodules.

Aim: To evaluate the influence of demographic, clinical and echographic characteristics in the recurrence of ND FNAC in a thyroid nodule.

Methods: Retrospective review of ND thyroid FNAC performed between 2017-2020. Demographic and clinical data (age, gender, cervical radiotherapy, presence of Hashimoto’s thyroiditis and TSH value) and US characteristics (nodules’ size, echogenicity, composition and microcalcifications) were collected at the moment of the first ND FNAC.

Results: Of 230 nodules with a first ND FNAC (patients’ mean age 60.2±14.1 years, 83% women), 195 (84.8%) were submitted to another FNAC, 9 (3.9%) were submitted to surgery (only 1 had a malignant histology) and 26 (11.3%) remained under US surveillance. The second FNAC result was: benign in 121 cases, non-diagnostic in 63, indeterminate in 9 and malignant in 2. Concerning demographic and clinical data, there was a higher risk of a second ND FNAC in patients treated with anticoagulant/anti-aggregating agents (OR 2.2, 1.1-4.7, P=0.03). Men had a reduced risk of a second FNAC (OR 0.4, 0.2-0.9, P=0.016). Patients who had a second ND FNAC were older (63.4±14 vs 59±14 years; P=0.032). Previous cervical radiotherapy and Hashimoto’s thyroiditis did not influence the risk of a second ND FNAC. Regarding echographic characteristics, nodules’ echogenicity differed between the ND and diagnostic FNACs (hypoechogenic 71.9% vs 52.4%, hyperechogenic 1.6% vs 6.6% and isoechogenic 26.6% vs 41.8%; P=0.031); however, nodules’ composition was not significantly different between them. Nodules’ microcalcifications increased the risk of ND FNAC (OR 2.2, 1.1-4.5, P=0.03). Nodules’ size and TSH value were not significantly different between ND and diagnostic FNACs. Eight out of 63 cases with a second ND FNAC were submitted to surgery (all with benign histology), 17 were submitted to a third FNAC (8 benign, 6 ND and 3 indeterminate), in 21 was decided US follow-up and 17 patients dropped out of the study. No malignant diagnosis was found in the nodules with 3 ND FNAC.

Conclusion: In the current series, a second ND FNAC occurred in almost one third of cases. Female gender, older age, treatment with anticoagulant or antiaggregating agents, hypoechogenic nodules and the presence of microcalcifications are likely to influence results. In addition, these nodules were rarely malignant (1.3%).