Clinical and pathological characteristics of incidental and nonincidental papillary thyroid microcarcinoma in 339 patients.

Background: We analyzed the incidence and the clinicopathological characteristics of papillary thyroid microcarcinoma (PTMC) in a high prevalence region of goiter with the purpose to investigate differences between incidental and nonincidental PTMC.

Methods: A total of 2236 patients who underwent total thyroidectomy from 2001 to 2009 were reviewed retrospectively. Papillary carcinoma was diagnosed in 583 patients. Of these, 339 patients with PTMC were included in the study. Clinicopathological features were evaluated by univariate and multivariate analysis.

Results: The prevalence of incidental PTMC was 12% of all patients who underwent surgery for thyroid disease. Univariate analysis showed that bilaterality (p = .001), autoimmune thyroid disease (p = .049), size of tumor >5 mm (p < .001), multifocality (p < .001), lymph node metastasis (p < .001), and capsule invasion (p < .001) were significantly associated with nonincidental PTMC. The incidence of lymph node metastasis in incidental PTMC was 5% versus 33% in nonincidental, suggesting that the biological behavior may be different in the 2 categories.

Conclusions: Our results indicate that a high rate of PTMC presented 1 or more risk factors including multifocality, bilaterality, capsule invasion, and lymph node metastasis. Therefore, we suggest total thyroidectomy followed by adequate exploration of the central neck compartment for possible nodal involvement and resection as a safe therapeutic approach.