The Malignancy Risk Assessment of Cytologically Indeterminate Thyroid Nodules Improves Markedly by Using a Predictive Model.

Objectives: The majority of thyroid nodules are discovered incidentally, and the management may be a challenge if the fine needle aspiration specimen yields indeterminate findings. Our aim was to develop an individualized risk prediction model to provide an accurate estimate of cancer risk in patients with cytologically indeterminate thyroid nodules.

Materials And Methods: Clinical records, ultrasound images, and cytopathology reports of patients who underwent thyroidectomy were retrospectively reviewed. Logistic regression analysis was used to identify the predictive ability of each variable for malignancy, and a nomogram was built by integrating patients' age, multiplicity of nodules, cytology results, and suspicious ultrasound features, such as microcalcifications and irregular margins.

Results: For the 233 indeterminate nodules according to the Bethesda System for Reporting Thyroid Cytopathology, the malignancy rates of the subgroups "atypia of undetermined significance," "suspicious follicular neoplasia," and "suspicious for malignancy" were 44.3, 47.7, and 88.0%, respectively. It was found that the Bethesda category "suspicious for malignancy," microcalcifications, and irregular margins were independent risk factors for malignancy. The area under the receiver operating characteristics curve was 0.784, which suggested that the presented nomogram had considerable discriminative performance.

Conclusions: The nomogram developed in our study accurately predicts the malignancy risk of thyroid nodules with indeterminate cytology by using clinical, cytological, and ultrasonographic features.