[Thyroid cancers masked by hyperthyroidism. 12 cases].

The main object of this report was to attract again attention to the fact that obvious hyperthyroidism does not exclude the possibility of associated thyroid carcinoma, although this is an exceptional association. The 12 cases presented here may be added to about 30 cases found in the world literature. They were observed over a period of 13 years by the same surgical team and correspond to 0,3 p. 100 of all thyroid operations, 1 p. 100 of operated cases of hyperthyroidism and 3,6 p. 100 of cases of thyroid carcinoma. Contrary to most published cases, 11 or these cases out of 12, presented, clinically, mainly as hyperthyroidism the carcinotous lesion was either palpabale clinically in the form of a very small nodule (6 cases) or totally latent and discovered operation or even on histology as in 5 cases. Hyperthyroidism produced in 3 cases the classical picture of Graves' disease, in 6 cases that of toxic nodular goiter and, in 2 cases, that of a solitary toxic adenoma. The hyperplasia and the carcinoma were always in anatomically different areas. There is no apparent physiopahtological link and the classical notion of para-neoplastic hyperthyroidism seems debatable in most cases presented here, even in the cases of diffuse hyperfunctional hyperplasia. In any case, whatever the pathogenesis of this association, its possibility should be brought to mind in a case of hyperthyroidism. Surgery should always be advised in cases of toxic adenoma and in Graves' disease when the goiter is irregular and, especially, when a nodule is found. The course and prognosis seem to be mainly dictated by the histological type and the local spread or distant spread of the carcinoma, hyperthyroidism does not aggravate seriously the prognosis.