Extensive vascular invasion is a marker of risk of relapse in encapsulated non-Hürthle cell follicular carcinoma of the thyroid gland: A clinicopathological study of 18 consecutive cases from a single institution with a 11-year median follow-up

Aims: To determine the prognostic value of certain clinicopathological features in a series of 18 consecutive cases of encapsulated follicular carcinoma (EFC) of the thyroid gland with long follow-up. Methods and results: Eighteen consecutive cases of EFC were retrieved from 1975 to 1993. Gender, age at onset, type of surgery, presence of capsular and/or vascular invasion, number of involved vessels, tumour size, and TNM/pTNM classification were evaluated and correlated with disease outcome. None of the cases presented with distant metastases. Extensive vascular invasion (defined as more than four capsular vessels involved) was present in two cases. After a median follow-up of 133 months, all patients were alive. Three cases had relapsed in lung and bone. In two out of these three cases, extensive vascular invasion was present. Radioiodine therapy was curative in two of three of the relapsed cases. Conclusions: EFC is a low-risk carcinoma, with no patients' deaths after a median follow-up of 11 years. Extensive vascular invasion should be considered as a risk factor for relapse. A conservative surgical approach is recommended. Since relapses may occur up to 14 years after the initial surgery, life-long follow-up is advisable.