Impact of lymphovascular invasion on otherwise low-risk papillary thyroid carcinomas: a retrospective and observational study

PurposePresence of venous vascular invasion is a criterion of intermediate risk of recurrence in papillary thyroid carcinoma (PTC). However, the presence and type of vascular invasion (lymphatic or venous) is often underreported and its impact on PTCs without other risk features remains unknown. The aim of this study was to evaluate the impact of both lymphatic and venous invasion on the risk of recurrence/persistence on otherwise low-risk PTCs.MethodsRetrospective study including patients with otherwise low-risk PTCs but with vascular invasion, diagnosed between 2013 and 2019. The persistence/recurrence during the follow-up was evaluated. Pathology was reviewed to confirm the presence of lymphovascular invasion and determine the type of invasion.ResultsA total of 141 patients were included. Lymphovascular invasion was confirmed in 20.6%. After surgery, 48.9% (N = 69) of the patients received radioactive iodine (RAI). The median follow-up time was 4 [3-6] years. Overall, 6 (4.2%) patients experienced persistent/recurrent disease in the neck, including 3 with lymphovascular invasion, confirmed as "only lymphatic". Overall, patients with tumors harboring lymphovascular invasion had sensibly more persistent/recurrence disease compared with those without lymphovascular invasion (10.3% vs 2.7%, p = 0.1), especially in the subgroup of patients not treated with RAI (20% vs 1.6%, p = 0.049) [OR 15.25, 95% CI 1.24-187.85, p = 0.033].ConclusionLymphovascular invasion, including lymphatic invasion only, is associated with a sensibly higher risk of persistent/recurrent disease in otherwise low-risk PTCs, namely in patients not treated with RAI. Lymphatic invasion could have a role in risk-stratification systems for decision making.