Appropriate Surgical Procedure for Dominant Thyroid Nodules of the Isthmus 1 cm or Larger

Hypothesis: Surgeon-performed ultrasound (SUS) and fine-needle aspiration (FNA) may guide the management of dominant thyroid nodules of the isthmus. Design: Retrospective review of prospectively collected data. Setting: Tertiary academic referral center. Patients: Of 942 patients who underwent preoperative SUS and FNA, followed by thyroidectomy, between January 1, 2002, and April 10, 2010, a total of 28 patients had a dominant thyroid nodule of the isthmus. Main Outcome Measures: Preoperative SUS features and FNA findings and final pathologic results. Results: Of 28 patients (3%) who had a dominant thyroid nodule of the isthmus, 16 had benign final pathologic results, with all having at least 2 benign SUS features and 9 having 3 benign SUS features; 15 of 16 patients had an FNA finding that was benign or indeterminate. Of 12 patients with malignant final pathologic results, 8 had 3 malignant SUS features, and all had an FNA finding that was malignant or suspicious for a malignant neoplasm. Among these 12 patients, final pathologic results demonstrated multifocal disease (8 patients), extracapsular invasion (4 patients), or lymph node involvement (7 patients). When 11 patients with a malignant dominant thyroid nodule of the isthmus were compared with an overall group of 270 other well-differentiated papillary thyroid carcinomas 1 cm or larger on final pathologic results, patients with isthmus nodules trended toward having higher rates of multifocal disease (P=.08), extracapsular invasion (P=.09), and lymph node involvement (P=.09). Conclusions: Preoperative SUS features and FNA findings in patients with dominant thyroid nodules of the isthmus can accurately predict malignant or benign thyroid disease and direct the extent of thyroidectomy. For malignant isthmus nodules, total thyroidectomy and possible central node dissection are recommended owing to high rates of multifocal disease and lymph node involvement. For benign isthmus nodules, thyroid lobectomy with isthmusectomy or isthmusectomy alone may be appropriate.