47 from the areas of the more heavily exposed groups. Three other subjects from this island with the same exposure have had surgical excision of nodules which proved to be benign adenomas. A fifth lesion that was papillary (the size of a match head) was foundin a subject from anisland where the exposure was intermediate (Ailingnae); several other individuals exposed there have developed benignlesions after a latent period somewhatlonger than for those exposed on Rongelap. After review of this papillary lesion by eleven pa- thologists,* opinion is divided as to whetherit should be considered malignant (Figure 344); we have recorded it in ourstatistics as benign in view of the majority opinion. A few lesions of the thyroid fall into an uncer- tain category in which even the most experienced *Drs. S. Warren, W. Meissner, and M.A. Legg, New England Deaconess Hospital; J.D. Reid, Cleveland Metropolitan Gen- eral Hospital; T. Winship (deceased); L.B. Woolner, Mayo Clinic; L.V. Ackerman, SUNYat Stony Brook; R.V. Rosvoll, Emorv University; and S. Robbins, A. Vickery, and B. Castleman, Massachusetts General Hospital. pathologists are unable to reach a firm opinion as to a diagnosis of malignancy. Someofthese lesions ultimately proved to have been malignant as evi- dencedbya distant metastasis some years after re- moval of the primary lesion. It seems that a neoplasm must reach somesignificant size beforeit can unequivocallysatisfy the criteria for a diagnosis of malignancy even though smaller lesions may have cellular characteristics that suggest malignant capabilities. In clinical practice many lesions are of sufficient size that the criteria for malignancyarereadily fulfilled.Among the Marshallese patients most of the thyroid noduleseither were detected by palpation when scarcely | cm in diameter or were found coincidentally to removal of palpable adenoma. Manylesions showing atvp- ical cellularity were so small that perhaps they had not yet had an opportunity to manifest all the usual criteria upon which a diagnosis of malig- nancy maybe based. Figures 33C and 344 show one such minute lesion. This emphasizes the importanceof the early diagnosis and treatmentof Marshallese lesions. ShigeUz SighSeaiieer 8, V e aia meses a “ate SPA * ae aa > v. “ae s 4 OP . ost ath ree RL 3.2: ase:6 mF 4a wat “a see oP yrs ~— a a : “ 3 ow a a te Nsep" is a SFseen 4: Tt a Ay g ts : PAEeeeeSNaeenteghs, . We 3 we Figure 34. Examples of very minute neoplasms, only a few mm in diameter and completely en- capsulated but composedofcells whose pattern suggests thatif the lesions were larger they might display features prompting a suspicion of malignancy. In both examples shown (A, x 162, sub- ject No. 8, 1972; B, x 91, No. 36, 1969) evidence of blood vessel or lymphatic invasion is lack- ing, and the capsule, which was very thin, was not breeched. Theentire lesion of A is shown in Figure 33C, where its size can be compared with that of surrounding normalfollicles. Both these examples are from thyroids that had no frankly malignantlesions elsewhere in them.