The large majority of 1520 patients with indeterminate thyroid nodule at cytology have a favorable outcome, and a clinical risk score has a high negative predictive value for a more cumbersome cancer disease.

CONTEXT: Clinical management of patients with thyroid nodules indeterminate at fine-needle aspiration (FNA) cytology is still unsettled.

OBJECTIVE: Our objective was to establish the clinical outcome of patients with thyroid nodules indeterminate at cytology and to identify the features associated with malignancy.

DESIGN AND PATIENTS: This was a retrospective evaluation of 1520 consecutive patients with indeterminate cytology among 100 065 patients who underwent FNA between January 2000 and December 2010.

RESULTS: Of 1520 patients, 371 (24.4 %) had thyroid cancer at histology, the follicular variant of papillary cancer being the most frequent histotype, and 342 patients with cancer were free of disease after thyroidectomy and (131)I remnant ablation, whereas 29 needed further treatment because of persistent disease. Among them, only 12 had persistence of disease at the end of follow-up. Atypias at cytology (P = .001), blurred nodule margins (P = .005), and spot microcalcifications (P = .003) at thyroid ultrasound (US) were significantly associated with malignancy. A clinical score including cytology and US characteristics was calculated; the lowest value showed a high negative predictive value (83.9%) for the presence of malignancy and even higher (99.5%) for the presence of a more cumbersome cancer disease, and only 4 of the 29 patients who needed further treatment were included in the group with the lowest risk score.

CONCLUSIONS: Patients with Thy 3 cytology and histology of thyroid cancer had an overall good prognosis. A clinical risk score including the results of cytology and US features is helpful in the management of patients with indeterminate thyroid nodules.