Differential Diagnosis of a Follicular Carcinoma and Papillary Carcinoma of the Thyroid Gland Based on Sonographic Findings

ABSTRACT

PURPOSE: The purpose of this study was to evaluate and compare the sonographic findings of a conventional papillary carcinoma, follicular carcinoma and a follicular variant of a papillary carcinoma. MATERIALS and METHODS: A total of 308 nodules from 231 patients that were diagnosed with a papillary carcinoma and a follicular carcinoma by surgery after sonography were analyzed. The nodules consisted of a conventional papillary carcinoma (255, 83%), a follicular variant of a papillary carcinoma (25, 8%), and a follicualar carcinoma (28, 9%). We compared and analyzed the sonographic findings of each nodule for content, margin, echotexture, shape, calcification and halo sign. RESULTS: A conventional papillary carcinoma showed significant different sonographic findings than a follicular carcinoma and a follicular variant of a papillary carcinoma for an ill-defined or well-defined spiculated margin (63.1%), marked hypoechogenicity (85.9%) and microcalcification (49%). A follicular carcinoma showed a significant difference than a conventional papillary carcinoma for a well-defined smooth margin (92.9%), iso, hypo- or hyperechogenicity (89.3%), wider than tall shape (100%) and halo sign (82.1%). The follicular variant of a papillary carcinoma showed similar findings to a follicular carcinoma except for marked hypoechogenicity (44%, p = 0.006) and taller than wide shape (16%, p = 0.027). CONCLUSION: The follicular carcinoma and follicular variant of a papillary carcinoma showed similar sonographic findings, but findings of a conventional papillary carcinoma were different.