Nodal metastasis and recurrence in papillary thyroid microcarcinoma.

Despite the majority of papillary thyroid microcarcinoma (PTMC) patients has benign clinical courses, some PTMCs have a clinical presentation similar to conventional papillary thyroid carcinoma (PTC). The aim of this study was to identify risk factors for lymph node metastasis at presentation and prognostic parameters influencing nodal recurrence in PTMC. From January 1998 to October 2013, 556 consecutive patients had a diagnosis of differentiated thyroid carcinoma in our surgical department. A total of 219 (39.4 %) patients who had a pathological diagnosis of PTMC represented the cohort for the current study. We carried out a retrospective cohort study to compare 24 PTMC patients with lymph node metastasis at diagnosis (N1) and 195 PTMC patients without lymph node involvement (N0). The comparison between groups involved evaluation of patients and tumor characteristics. A diameter >8 mm, the presence of multifocality, and extrathyroid invasion (T3) were independent risk factors for nodal involvement at presentation. The presence of T3 was the only independent prognostic parameter influencing nodal recurrence. Prognostic factors for N1 at presentation and for recurrence are pathological parameters, thus it is not possible before surgery to detect PTMC patients who are at risk. However, we believe that a full treatment protocol should be also indicated in the case of PTMC according to risk stratification and cancer stage as for the conventional counterpart of PTC.