The Sonographic Subcentimeter Malignant Thyroid Nodule: What Does It Stand for?

Thyroid cancer management has moved to less extensive surgery in lesions with favorable criteria. Our study evaluated if the sonographic (US) size of thyroid nodules is a reliable criterion to determine the extent of surgery in patients with papillary thyroid carcinoma (PTC). A retrospective study was performed to evaluate thyroid nodules measuring <10 mm in the preop sonogram with a permanent pathology of PTC. Patients were subdivided into two groups based on the US size: A (1–5 mm) and B (6–10 mm). Statistical correlations were made for the presence of the following unfavorable criteria: multifocality, capsular invasion, angio/lymphatic invasion, extrathyroidal invasion, and presence of metastases. A total of 1901 thyroidectomies were performed: 722 (38%) for PTC. 182 (25%) patients met the inclusion criteria. There were 30 patients in Group A (1–5 mm) and 152 patients in Group B (6–10 mm). Five (17%) patients in Group A and 53 (35%) patients in Group B presented unfavorable criteria (P < 0.005). Malignant thyroid nodules with the US size of <5 mm can in theory be candidates for partial thyroidectomy, but 17 per cent of them might still need further surgical intervention. Lesions with the US size of 6 to 10 mm still have a moderate risk of presenting unfavorable pathological criteria.