Implications of a background of Hashimoto's thyroiditis on the current conservative surgical trend towards papillary thyroid carcinoma.

The purpose is to delineate the clinico-pathologic features of papillary thyroid carcinoma (PTC) occurring in a background of Hashimoto's thyroiditis (HT). A retrospective analysis of consecutive PTC patients who underwent surgery at an academic center between Jan. 2010 and Jan. 2020 was performed. The primary end point was to assess whether a background of HT implied a higher likelihood for postoperatively determined high-risk histopathologic features. Accordingly, its implication on initial surgical planning. Tumor high-risk features included aggressive histologic variants, lymphovascular invasion, extrathyroidal extension, multifocality, and positive nodal metastasis. To achieve the primary outcome of interest, a two group-designation was followed: group A (none-HT-group) and group B (HT-group). The two groups were also compared regarding postoperative complications as a secondary outcome of interest. In the specified period, 331 patients were found to have a histologically proven diagnosis of PTC. Group A accounted for 80% (265/331) of the study cohort, while group B accounted for the remainder 20%. PTC was significantly more prevalent in the absence of HT (p < 0.0001). Both groups were comparable in mean-patient-age. However, Group B demonstrated a considerably higher male:female ratio (1:10 vs. 1:3; p = 0.01). All postoperatively determined high-risk histopathologic features were comparable in both groups (p > 0.05). Nevertheless, transient hypoparathyroidism was considerably higher in group B (12% vs. 23%; p = 0.02). A background of HT does not seem to reflect a more aggressive cancerous biologic behavior. Therefore, it should not preclude the conservative surgical strategy adopted by the most recent clinical practice guidelines.