Intrathyroidal differentiated thyroid carcinoma: tumor size-based surgical concepts

Total thyroidectomy (TT) remains the treatment of choice for differentiated thyroid carcinomas (DTCs), but a limited approach can be proposed when tumors are at an early stage and limited to a single lobe. The aim of this study was to analyze the pathologic and clinical aspects of a retrospective series of DTCs in an attempt to determine whether these features might prove useful for limiting the surgical strategy in selected cases.

From 2000 to 2005, a total of 2798 patients (637 males, 2161 females; mean age 44.6 years) underwent TT for papillary thyroid carcinoma in our department. The histologic features considered were size, histologic subtype and capsule of the tumor, its multifocality/bilaterality, infiltration of the thyroid capsule, and the presence of nodal metastases.

Statistical analysis revealed that among tumors < or = 1 cm the presence of the tumor capsule, infiltration of the thyroid capsule, bilaterality, and the presence of node metastases were all significantly lower when the tumor size was < or = 0.5 cm (p < 0.0001). Furthermore, patients with bilateral carcinomas demonstrated a significantly higher presence of a tumor capsule (p = 0.012), infiltration of the thyroid capsule (p < 0.0001), and node metastases (p < 0.0001) and a higher incidence of the "tall-cells" variant (p < 0.0001) when compared to the unilateral population.

Based on these data it is suggested that tumors < or = 1 cm cannot be considered a homogeneous class of DTCs. Nevertheless, in tumors < or = 0.5 cm the absence of a "tall-cells" variant and the absence of infiltration of the thyroid capsule might be useful for avoiding an unnecessary completion thyroidectomy after lobectomy.