ABSTRACT Objective Warthin-like papillary thyroid cancer (WL-PTC) is an uncommon variant of PTC, usually associated with lymphocytic thyroiditis. Scarce evidence suggests that WL-PTC has similar clinical presentation to classic PTC (C-PTC), with no studies comparing risks of recurrence and response to treatment between both variants. Our objective was to describe the clinical presentation and prognosis of WL-PTC and compare it to C-PTC. Subjects and methods Retrospective analysis of a prospective cohort, including 370 (96%) patients with C-PTC and 17 (4%) with WL-PTC, consecutively treated with total thyroidectomy with or without RAI, followed for at least 6 months. We compared clinical presentation, risk of mortality and recurrence, as well as response to treatment between both variants.

Results Of the total cohort:

317 (82%) female, 38 ± 13.5 years, median follow-up 4 years (0.5-28.5); most of them stage I and low/intermediate risk of recurrence. We found no differences regarding clinical-pathological data and risk of recurrence. WL-PTC was associated with a higher rate of anti-thyroglobulin antibodies (TgAb) (65% vs. 36%, p = 0.016) and lymphocytic thyroiditis (59% vs. 34%, p = 0.03). The rates of biochemical and structural incomplete responses were similar in both variants. WL-PTC had a lower rate of excellent response (23% vs. 54%, p = 0.01), which became non-significant when performing analysis by TgAb presence (50% vs. 67%, p = NS). Conclusions WL-CPT and C-CPT have similar clinical presentation and rate of recurrence. The lower rate of excellent response to treatment in WL-PTC is due to a higher frequency of TgAb. WL-PCT should not be considered an aggressive variant of PTC.