recent patients had received small tracer doses of radioiodine the day. before surgery so that the nodular tissue could be measured for radioactive content at the time of surgery. The c’screte lesions in many instances showed !31, uptakes which were different from the extra nodular tissue. Most - of the discrete benign lesions showed less uptake than the extra nodular surrounding tissue (Fig. 5 ). Measurement of radioiodine in the malignant tissue was found to be nil compared with the surrounding more normal tissue. Microscopic examination of the benign lesions revealed marked variation | in size of follicles. The cells of some follicles appeared atrophic, - while others were hyperplastic, which was reminiscent of iodine deficiency goiter (Fig. 6 }). In addition to the gross adenomatous masses in the 15 thyroids which were classified as benign there were multiple microscopic clusters of what appeared to be atypical proliferating cells here and’ there in the parenchyma of some of these thyroids (See Figs.7 and 8). Microscopically the thyroid carcinomas were considered of low grade’ malignancy and varied in structure from papillary to mixed papillary and follicular type. Benign adenomatous changes were also noted in the glands. - All showed capsular invasion and_in 2 cases localized metastases to lymph nodes was present and in 2 other cases blood vessel metastases were noted ._ (Figs. 9 and 10 ). Total thyroidectomies were performed in all 3 cases of malignancy and a left radical cervical lymph node dissection was carried out in l case’ because spread to lymph nodes was seen. f No . metastases have been recognized beyond the cervical region in any patients. - DOE ARCHIVES