MACROFOLLICULAR VARIANT OF PAPILLARY THYROID-CARCINOMA WITH MINOR INSULAR COMPONENT

BACKGROUND. The macrofollicular variant of papillary thyroid carcinoma that is the subject of this study has only recently been characterize d. Information about its morphologic spectrum and biologic behavior is limited. METHODS. The authors reviewed 29 examples, including 17 prev iously reported cases. The clinical and pathologic features of five pa tients who had the macrofollicular variant of papillary thyroid carcin oma with a minor insular component were analyzed in detail. The insula r component in thyroid carcinomas has been associated with aggressive clinical behavior. RESULTS. The ages of the 5 patients ranged from 31 to 70 years; the mean age was 40 years. Three patients presented with a palpable thyroid nodule and two with a large thyroid mass of long du ration. The latter two tumors, which metastasized, were the largest (8 and 11 cm) and showed extrathyroidal and blood vessel invasion. All f ive tumors were composed predominantly of macrofollicles (>50%) and ha d a minor insular component that comprised less than 5% of the tumor m ass. In most tumors, the macrofollicles were lined by cells with large , clear, grooved nuclei, and all five contained areas of conventional follicular variant of papillary thyroid carcinoma. In the two that met astasized, however, the lining of many macrofollicles consisted of cub oidal cells with small, hyperchromatic, follicular-type nuclei. Only t he macrofollicular component was identified in the metastatic deposits in these two patients. All five patients were alive at last follow-up , two with metastases; but follow-up for this study is limited. CONCLU SIONS. A minor insular component is an additional feature of the macro follicular variant of papillary thyroid carcinoma that may aid in diag nosis and does not appear to have an adverse effect on the excellent p rognosis of patients with these tumors. (C) 1997 American Cancer Socie ty.