Pure versus follicular variant of papillary thyroid carcinoma: clinical features, prognostic factors, treatment, and survival.

Background: The follicular variant of papillary thyroid carcinoma (FVPTC) is a common subtype of papillary thyroid carcinoma. Few studies have compared the clinical behavior and treatment outcome of patients with FVPTC with the outcome of patients with pure papillary carcinoma (PTC). A retrospective study was performed to identify the influence of FVPTC compared with PTC on therapeutic variables, prognostic variables, and survival.

Methods: A clinicopathologic analysis of 243 patients with papillary carcinoma was performed. One hundred forty-three tumors were PTC, and 100 tumors were FVPTC. The following variables were evaluated: age at diagnosis, tumor size, stage of tumor, treatment, capsular invasion, and survival.

Results: The median follow-up was 11.5 years. The median age was 43 years in the PTC group and 44 years in the FVPTC group. The median tumor size, disease stage, and type of initial surgery and iodine 131 ablation were similar. More patients had capsular invasion by the tumor and less metastases to cervical lymph nodes in the FVPTC group. The actuarial survival of patients age < 40 years was higher compared with the survival of patients age > 50 years in both groups. The 21-year overall actuarial survival was 82% in patients with PTC and 86% in patients with FVPTC (P value not significant).

Conclusions: The pathologic and clinical behaviors of PTC and FVPTC were comparable. Prognostic factors, treatment, and survival also were similar. Patients in both groups must be treated identically.