Risk factors contributing to the difference in prognosis for papillary versus micropapillary thyroid carcinoma

The aggressiveness of papillary thyroid carcinoma (PTC) was evaluated by comparing conventional PTC with papillary thyroid microcarcinoma (PTMC). Risk factors associated with differences in clinical and pathologic features were analyzed to provide appropriate surgical management.

A total of 539 patients with papillary carcinoma who underwent total thyroidectomy were retrospectively reviewed. The median follow-up period was 32 months.

Of 539 patients, 311 (57.7%) had PTMC, and 228 (42.3%) had conventional PTC. No differences between patients with PTMC and those with PTC were observed in age, gender, and multifocality. PTMC was associated with less frequent bilaterality (P = .002), lymph node metastasis (P < .001), thyroid capsule invasion (P < .001), and disease recurrence (P < .001), and a higher rate of incidental diagnosis (P = .001). There was no statistically significant difference between the prevalence of lymph node metastasis at diagnosis and disease recurrence rate between nonincidental PTMC and conventional PTC (P > .05).

Incidental PTMC had significantly fewer aggressive tumor features. Nonincidental PTMC presented with aggressive characteristics similar to those of conventional PTC and should be treated likewise. The authors suggest routine total thyroidectomy followed by an adequate exploration of the central neck compartment as a safe treatment.