the non-nodular thyroid tissue and in many cases took up none at all (Figure 32). Gulyin one individual a single lesion, which was papillaryin char. acter, took up more radioiodine than the surround. ing normal Unyroid tissuc. Although reduced radio- were very firm, pale brown or whitish, In some there were hemorrhagic or degenerative cysts. The inargins of some other nodules were indistinct, producing a lobular character which comprised niost of the thyroid in such a manner that the entire gland appeared to be responding to a disuse pathologic process, not untike the type of gland observed in chronic iodine deficiency but ia miniature proortions, ah raat (Figure 31), but all except two of thase that were papillary were considered benign, Most of the it dividuals operated on later in che scrwere given asmalb tracer dose of" Pso that the fianectieanal natuer of Che adenomatous arcu could be studied for radiviudine uptake.*'"" Multiple autaradiographs prepared from tissues from the bast 13 pa- icnts have shown that esseatially all the discrete lesions took up signilicantly Jess radioiodine than jadine uptake does nut necessarily badicute a ma Rynant lesion, itis commonly observed tht lesions having a capacity to metastasize take up Car less radioiodine than the exuanodular tissue (usually the ratio is < Yee), Most of the thyroids have been found te cantain an unusual number of minute encapsulatedlesions, some of them: consposed ofsolid cellular mnasees of cells (Figure 33.1, 4, and 2), in contrast to lesions fund in must adcnomatous goiters, which are compused of follicular structures similar to but not Klentical to normal of hyperplasiic glands, On carcful gross examination of the glands, these ai. nute lesions appeared as tiny whitish dow ~ bmi in diameter (pinhead size). The atypicality of these lesions and the presence of mitoses in the ecls of some of them give rise tu speculation regarding their uluimate malignant petential (Figure 344 and # and Figure $3/)). especially since several obviously malignant lesions have been foundia this exposed population, Phe lesions shown are from thyroids not harboring frankly waligaant lestons ebewhere, except the lesion in Figure $34, which was fuund in a thyroid that alsa had a Figure 30. Gross serial sections of an irradiated Marshallwe thyroid, showing multiple dix rete adenomata devel- oping throughout bath lobes ofthe thyreid, Scarriaag is evident between these nodules, highly malignant lesion ina distant part, Of the four malignant losiens found (Figure 45), two were papillary adenocarcinomas displaying some arcus Chat were fess well dilfurentiated, com bee ure 30). In some instances these discrete lesions of adenomatous change. Many of the lesions were completely surrounded by a distince capsule and, unlike the remainder of the thyroid, had a distinet histological pattern which ranged from microfallicular tofetal, solid, or embryonal types. Unexpectedly many of the adenomas were papillary ee ~ ieee Ase: TRI: 1aterpabeeated ateaie me. ivy bye ie peared to be discrete with distinct capsules (Figs of the thyrvids revealed some nodules which ap- On microscopic examination all the thyroids of exposed Rongelap people showed varying degrees er :: rf 2. Microscopic Appearance Jeet we red Saha oieae ek VF ae Ae, * 2 3 when they were much smaller than nodules usually encountered in general clinical practice. Few of the lesions were visible fromthe exterior, and none was accompanied by symptoms, At the time of sargical exploration most of the thyroids in the exposed Rongclap people were lobutated and contained small discrete masses which were not of sullicicnt size to cause verysignificant enlargement of to distort the symmetry of the gland. Must of the glands in the exposed Rongelip peopie with anty one palpable nodule proved to have multiple nodules, Often the palpated nodule was not the lesion that uluimately prompted the mast concern on histological exanainaton, ‘The gland in sume cases showed many tortuous hair-like vessels on the surface, reminiscent of thyroids that had previously been treated with eadioactive iodine for hyperthyroidism. Vhe cut surface