["Occult" carcinoma of the thyroid: clinical, morphological, and biologic characteristics for a correct therapeutic...

The "occult" carcinoma of the thyroid is still a highly controversial topic. The controversies not only regard its diagnosis, treatment, natural history and, therefore, its biological potential, but also aspects of a nosological nature in that there is still no unequivocal acceptance of its originality, thus leading to discussions focused on its precise definition. On the basis of our experience and other published data, we have reached the following conclusions: a) the term "occult" carcinoma of the thyroid must be used to describe a neoplasia which does not exceed 1.5 cm in diameter, irrespective of the presence or otherwise of laterocervical adenopathy, and leaving aside the fact that it can be identified using clinical and instrumental tests; b) high-resolution echography and echo-guided FNA are fundamental instruments for a correct and early preoperative diagnosis; c) the clinical, morphological and, above all, biological (a very slowly evolving neoplasia) characteristics make the occult carcinoma of the thyroid seem to be a tumour with its own nosological identity; d) on the strength of the latter, and in particular in view of its natural history, conservative surgery (lobectomy with isthmectomy), in the differentiated forms, might play a primary role in the treatment of occult carcinoma of the thyroid in the very near future. However, at present complete thyroidectomy represents the treatment of choice even in differentiated forms, whereas lobectomy is only reserved for incidental cases of occult carcinoma discovered during the final histological test; e) lymphadenectomy is indicated in the event of lymph node involvement, not to achieve a longer survival rate but to reduce the incidence of recidivation in the form of lymph node metastases. In these cases, even the mere removal of macroscopically damaged lymph nodes is sufficient to ensure the virtual absence of recidivation on which, it is worth noting, metabolic radio-iodotherapy is efficacious in the large majority of cases.