FOLLICULAR VARIANT OF PAPILLARY THYROID-CARCINOMA - A CLINICOPATHOLOGICAL STUDY

Background. A retrospective clinicopathologic study was performed to i dentify the influence of diagnostic and therapeutic procedures on the outcomes of patients with the follicular variant of papillary thyroid carcinoma (FVPTC). Methods. The results of 37 patients with FVPTC were compared with those of 37 randomly selected patients with papillary c arcinoma and 22 patients with follicular carcinoma. Diagnostic, therap eutic, and follow-up data were obtained by review of clinical and hist ologic materials. Results. Median follow-up was approximately 3 years in all groups. Fine-needle aspiration had a sensitivity of 75% for FVP TC, which was similar to that for papillary carcinoma. Frozen section evaluation had a sensitivity of only 27% for FVPTC but 94% for papilla ry carcinoma and 44% for follicular carcinoma. All patients for whom t he fine-needle aspiration specimen contained cytologic features of pap illary carcinoma and frozen section suggested a follicular lesion prov ed to have FVPTC. Consequently, hemithyroidectomy was performed three times more often among patients with FVPTC than among those with papil lary carcinoma. FVPTC tumors were modestly, but significantly, smaller than papillary carcinoma tumors (1.2 versus 1.6 cm). Metastases to ce rvical lymph nodes occurred least often in patients with FVPTC and usu ally were detected within 3 months of diagnosis. The frequency of dist ant metastases within this limited period of follow-up did not differ between FVPTC and papillary carcinoma. Conclusions. Fine-needle aspira tion appears to be superior to frozen section for identification of FV PTC, although the number of aspirations performed was limited. Greater use of aspiration may permit more appropriate surgical management of this disease. Local and distant metastases of FVPTC do not occur more often than do those of papillary carcinoma.