Diagnosis of thyroid carcinoma

Despite being one of the most frequent neoplasms occurring in the endocrine system, thyroid carcinoma is, nevertheless, a relatively rare event (0.5-1.5% of all malignant tumours in man); the differentiated forms are the most prevalent and are characterized by a high mean survival rate, whereas the very aggressive forms are rare and prognosis is unfavourable. Diagnostic evaluation of carcinomatous lesions, particularly in the early stages, may give rise to considerable difficulties at a clinical level due to the differentiation of the benign lesions, which are a frequent finding. The traditional clinico-semeiological and instrumental parameters, which, in the past, were used in the assessment of suspected malignancy, should not be considered as markers of malignancy; however, exposure to ionizing radiations during childhood may have a well defined role of risk. Following the recent progress in genetic and molecular studies, it is now possible to exploit genetic-molecular tumor markers and, at present, thyroid medullary carcinoma may be identified also in the absence of clinical evidence, particularly the familial form, thus allowing suitable prophylaxis in those subjects with specific genetic impairment (e.g. preventive thyroidectomy in infancy). Since no discriminating clinico-semeiological parameters are available, considering the aspecificity of scintigraphic findings and the lack of reliability of echographic imaging in providing data which enable us to distinguish a rare neoplastic pattern from the more frequent finding of a benign thyroid mass, fine-needle aspiration (FNA) cytology may today be considered the technique of choice in the screening of the thyroid nodule. Our experience in over 12,000 nodular lesions since 1982, has confirmed that the cytological examination is the most discriminating investigation, diagnostic reliability being far greater than that of traditional techniques. Considering the high frequency of thyroid nodule disease which rarely harbours a carcinomatous lesion, a very scrupulous diagnostic algorithm is mandatory. The FNA cytology, together with morphofunctional and immunological examinations, as well as dynamic exploration of the thyroid hypothalamo-pituitary axis, which allows a nosographic picture of the thyroid nodule disease, provides a more discriminating appraisal for the surgical approach to a single, solitary or prominent nodule.