[Hyperfunctioning thyroid carcinoma. Description of a case].

Differentiated thyroid cancers account for 1% of all neoplasias but only for 2.3% of thyroid nodules. A particular condition is represented by the association with hyperthyroidism, which is found in about 7% of cases. Even more rarely may be themselves cause of thyrotoxicosis. In the present paper, the case of a 66-year old male patient, bearing a recently appeared goiter, referred to us for suspicion of lung cancer and hyperthyroid symptoms, is reported. Among appropriate investigations, the finding of high titer of thyroglobulin in the aspiration needle and cytology examination suggested that thyroid lesion was primary and not metastatic, while scintiscan with J-131 isotope showed that excess of thyroid hormones was just due to it; histological diagnosis was of papillary carcinoma. As to the pathogenesis of the neoplasma during hyperthyroidism, a causal role of thyroid stimulating auto-antibodies has been suggested in the cases associated with Graves' disease, absent in our patient, which could elicitate cancer progression in the mean time. Interestingly, activating mutation of thyroid hormone receptor (TSH-r) gene has been demonstrated in a hyperfunctioning differentiated cancer. Notwithstanding the unexpected clinical behaviour may appear very rare, molecular biology studies on aspiration biopsies (FNAB) will allow, in the future, to better define the neoplastic nature of some hot nodules. In personal opinion, this particular pathology must be attently searched both for its implications in the prognosis and therapeutic strategy and because it could be less rare than generally considered up to now.