FALLOUT EFFECTS—MARSHALL ISLANDERS 63 the greater prevalence in the older ones among the unexposed people. The usual predominance of nodules in females was observed. Noteworthy was the development of benign nodules in two of three Rongelap men exposed in utero. In one, exposed at 22 weeks gestation, the thyroid was probably sufficiently functional to incriminate radioiodine transferred from the mother. In the other case, however, exposed at about 12 weeks gestation, the thyroid was probably not functional and perhaps the gamma exposure may have been responsible. Histopathologic diagnoses of Marshallese thyroid lesions have been furnished over the years by a number of pathologists? These are summarized in Table 4. Most of the benign nodules were “adenomatous nodules,” that is, did not fulfill the criteria of true neoplasms (44). These nodules were frequently multiple. The carcinomas wereall of the papillary type, which are considered to behave in a clinically more benign fashion than follicular carcinoma or more undifferenti- ated types (1,23,45). The occult papillary carcinomas (‘occult sclerosing carci- noma’’) (28,35) were found in association with adenomatous nodules. They were not listed in the malignant category in view of their generally recognized benign nature (21,23,27,51,61). No specific type of histologic lesion was noted in the exposed people, though histologic and cytologic changes associated with radiation injury, such as interstitial fibrosis, lymphocytic thyroiditis, and oxy- phylic changes (25,53) were observed in some of the exposed individuals. TABLE4. Histopathologic diagnoses of thyroid nodules (up to 1982) Exposed group No. in population No. with surgery Diagnosis? Adenomatous nedule(s) Adenoma Atypical adenoma or adenomatous nodule Occult papillary carcinoma Papillary carcinoma No diagnostic lesion 250 45 Unexposed? group . 1303 18 33 9 2 2 7 3 2 1 5 1 5 3 2 Includes unmatched younger Marshallese. * Includes more than one diagnosis in some cases. 3 The pathologists that have contributed include Drs. S. Warren (deceased), W. A. Meissner, and M. Legg (New England Deaconness Hospital, Boston); D. E. Paglia (UCLA); J. D. Reid and M. Petrelli (Cleveland Metropolitan General Hospital); J. Oertel (Armed Forces Institute of Pathology, Walter Reed Army Medical Center, Washington, D.C.); L. B. Woolner (MayoClinic, Rochester, MN); A. L. Vickery (Massachusetts General Hospital, Boston); L. V. Ackerman (S.U.N.Y. Stony Brook); W. Hawk (Cleveland Clinic, Cleveland); and D. Slatkin (Brookhaven National Laboratory).