Follicular Variant of Papillary Thyroid Carcinoma: Clinical Features and Surgical Strategy

ABSTRACT

PURPOSE: The follicular variant of papillary thyroid carcinoma (FVPTC) is difficult to diagnose and there is continuous debate regarding the optimal extent of surgery. METHODS: One hundred sixty three patients (17 male, 146 female; mean age 43.3 years), who underwent a thyroidectomy with a final diagnosis of FVPTC were divided into the total thyroidectomy group (Group I, n=74) and the less- than total thyroidectomy group (Group II, n=89). The two groups were compared with respect to the various clinicopathological characteristics. The mean follow up duration was 64.9 months (13~247 months). RESULTS: Group I showed a significantly higher sensitivity than Group II for the diagnosis. The age of the patients in Group I was significantly older than those in Group II. The frequency of multifocality, capsular invasion, and the incidence of a cervical lymph node metastasis were significantly higher in Group I. Therefore, Group I had a higher proportion of stage III and IV. The percentage of high risk patients according to the AMES (Age, distant Metastasis, Extent of primary tumor, and tumor Size) category and MACIS (distant Metastasis, Age, Completeness of primary surgical resection, extrathyroidal Invasion, and tumor Size) score was significantly higher in Group I. However, there was a similar rate of locoregional recurrence, distant metastasis, and survival in the two groups. CONCLUSION: When a diagnosis of FVPTC is made preoperatively or intraoperatively, definitive thyroid cancer surgery can be applied using the corresponding extent of surgery for an ordinary papillary thyroid carcinoma. However, if no definitive diagnosis is made, then a less-than total thyroidectomy is recommended as the initial surgery, and a complete thyroidectomy is reserved only for high-risk patients.