Papillary and follicular variant of papillary carcinoma of the thyroid: Initial presentation and response to therapy

INTRODUCTION: The 2 most common histologic variants of papillary carcinoma are pure papillary carcinoma (PTC) and follicular variant of papillary thyroid carcinoma (FVPTC). The purpose of this study is to compare the presentation and short-term response to therapy of these variants and to determine if FVPTC is a more aggressive form of thyroid cancer that warrants intensive therapy. METHODS: A retrospective chart review of patients treated for PTC and FVPTC between 1996 and 1999 was performed. Clinical variables were compared with the Wilcoxon Rank-Sum test or the Fischer's Exact Test. RESULTS: Of 160 patients with papillary thyroid carcinoma included, 114 (71%) had PTC and 46 (29%) had FVPTC. Mean follow-up was 38.6 months. FVPTC presented with larger tumors (median 1.5 cm vs 1.0 cm, P = 0.007) and higher tumor stage than PTC. PTC patients were more likely to present with local invasion and to have local recurrence (9.65% vs 0% for both variables). There were no significant differences in patient age, gender, vascular invasion, lymph node or distant metastases, surgical treatment, radioactive iodine therapy, remission, or mortality. CONCLUSION. FVPTC presented with larger original tumor size and higher tumor stage but a lower local invasion rate and recurrence rate than patients with PTC despite similar therapies. These data suggest that FVPTC and PTC carry similar prognoses in early stages and that FVPTC may have a reduced predilection for local invasion. Although further studies with longer follow-up are required, these results do not suggest that FVPTC warrants more aggressive therapy than PTC.