25 year-old female (#18) who was 21 years of age at exposure and a 21-year-old female (#72) who was 6 years of age at exposure. This latter case presented the first malignant thyroid lesion noted in the group ofheavily exposed children, who have the highest incidence of benign lesions. These recent findings greatly increase the concern about The third malignantlesion was in a woman from Utirik Island. Since the dose of radiation received by that group was very low,it is highly improbable that this lesion is attributable to radiation exposure. Surgical Exploration of Thyroid Nodules Thyroid operations have been preformedat the following times: 3 in 1964,* 3 in 1965,** 5 in 1966,** 4 in 1968,** and 5 in 1969.+ (Hospital summariesof cases operated in 1968 and 1969 are presented in Appendix 5.) At surgery the gross appearance of mostofthe thyroids was lobulated, but in addition they contained grossly discrete masses (see Figures 22 to 24). The benign. thyroid lesions exhibited multiple nodules varying in size from a few millimeters to several centimeters in diameter. They varied from soft to firm in consistency, and were hemorrhagic or in manyinstances cystic. Some thyroid glands had increased fine vascularity over the surface similar to that noted in thyroids previously treated with large doses of 1311 for hyperthyroidism. Some of the recent patients were given small tracer doses of radioiodine the day before surgery so that the radioactive content of the nodulartissue could be measured at the time of surgery. The discrete lesions in many cases showed 131] uptakedifferent trom thatof the extra-nodular tissue, most discrete benign lesions showing less uptake (Figure 25). Radioiodine in malignanttissue was found to be nil compared with that in surrounding normal tissue. Microscopic examination ofthe benignlesions revealed markedvariation in size offollicles. The cells of somefollicles appeared atrophic, while others were hyperplastic, which was reminiscent of iodine deficiency goiter (Figure 26). In addition to the gross adenomatous masses, some of the 15 thyroids classified as benign contained multiple C *By Captain C.A. Broadus (MC)USN,U.S. NavalHospital, uam. **By Dr. B.P. Coleock, New England Deaconess and Bapist Hospitals, Boston, Massachusetts. tBy Dr. BM, Dobyns, Cleveland Metropolitan General Hospi- Mm) f~> C3 evD co ¢ tal, Cleveland, Ohio. cn Re wie g crete RRR! pibentyer + Yes. wah radiation-induced neoplasmsin this population. microscopic clusters ofwhat appearedto be atypical proliferating cells here and there in the parenchyma(see Figures 27 and 28). From the microscopic examination the thyroid carcinomas wereconsidered of low grade malignancy, and they varied in structure from papillary to mixed papillary andfollicular type (Figures 29 and 30). Benign adenomatous changes werealso noted in the glands. All showed capsularinvasion, and in two cases localized metastases to lymph nodes were present and in twoothercases, blood vessel] metastases. Total thyroidectomies wereperformedin al! three cases of malignancy, anda left radical cervical lymph nodedissection also was donein one case because ofspread to lymph nodes. No metastases have been recognized beyond the cervical region in any patients. Thyroid Function: Correlation With Retardation of Growth in Children In somechildren with thyroid lesions, deficiency in serum thyroxine has been correlated with re- tardation of growth. The moststriking instances of hypothyroidism were in two boys who showed marked retardation ofstatural growth and bone age. By 1964, they had developed obvious atrophy of the thyroid gland with almost completeloss of thyroid function as evidenced by failure of the thyroid to take up muchif any iodine even after TSHstimulation. By this time their blood had low thyroxine and very high TSH levels. They showed bony dysgenesis, sluggish Archilles tendon re- flexes, puffy faces, and dry skin. Their response to thyroid hormone supplement as evidenced by growth spurt, improved appearance,etc., has been dramatic (see Figures 31 to 33). Several other children whodisplayed thyroid nodularity and whose statural growth was below average showed low or low-normal serum thyroxine values and poor radioiodine uptake after TSH stimulationindicating that their thyroids were functionally impaired and operating near their maximum capacity. Functional deficiency of the thyroid was not demonstrated in adults with nodules or carcinoma of the thyroid. Influence of Physiological Stress on Thyroid Abnormalities An assessment was madeof the relationship of the developmentof puberty to the occurrence of thyroid nodules. Degrees of pubescent changes have been recorded annually by a grading system. The two boys who showed greatest retardation of