Unusual malignant tumors of the thyroid gland.

BACKGROUND: Although situated on the last places among the statistical hierarchy of human malignancies, thyroid cancers (TC) are the most common tumors of the endocrine system. Follicular epithelium neoplasms account for more than 90% of these lesions with a favourable prognosis, while resting tumors (medullary, anaplastic, lymphoma, sarcoma etc) generally present a rapid unfavorable evolution with a low rate of survival. PATIENTS AND METHODS: In a series of 464 thyropathies personally treated, 72 cases of TC (15.5%) were identified. Fifty-seven patients presented epithelial TC a 34 papillary variant, 20 follicular variant and 8 mixed forms. Alongside these there were two medullary TC, 9 anaplastic TC and insular TC, and primary lymphoma and metastasis to the thyroid of a lung carcinoma each single case. Four cases have been described in patients who were aged 2-6 years at the time of the Chernobyl disaster. Out of the common types, based on our own taxonomic criteria, we selected a group of 36 TC with unusual clinical, histological and behavioural characteristics or particular pathological associations. RESULTS: Seven cases of occult TC, 7 cases with precessive adenopathy TC and 11 patients with TC associated with hyperthyroidism were registered. All of them underwent adapted thyroidectomies in which the presence of cancer was decisive for the extent of surgery. Medullary, insular and anaplastic TC were the most aggressive lesions and even extended surgery and complementary therapy failed to improve the prognosis of these patients. In the same category we included the cases presenting the coexistence of two TC types, pathologic dedifferentiation in recurrences and concurrent presence of another endocrine or nonendocrine cervical lesion. The a surgical dogma of total thyroidectomy cannot always be respected, so complementary therapeutic solutions must be applied. RESULTS were complex, registering steady recoveries in occult, hyperfunctioning and even in coexisting pathological lesions, but many recurrences and reinterventions with poor survival rates (a few weeks up to 2 years) in cases with reduced or absent histologic differentiation were also noted. Some lesions were inoperable. DISCUSSIONS AND CONCLUSIONS: Increasing clinician, surgeon and pathologist awareness of these distinct, but not rare anatomoclinical contingencies could contribute to their adequate diagnosis and treatment. Recent progress in knowledge of molecular carcinogenesis and promising successes of targeted chemotherapy trials with new drugs offer promising perspectives in the management of advanced or metastatic TC. Surgery still remains the cornerstone treatment for thyroid cancers.