ABSTRACT
The thyroid can provide an excellent model for studying the cytogenetic features and the molecular basis o f epithelial tumorigenesis in humans. In fact, beside the generation o f a spectrum of benign and malignant tumors, the
thyroid epithelium is rather unique in that it is simple and homogenous in its organisation, behaviour and differentiation and its growth is regulated by a single trophic hormone (TSH). These features contrast with the com plexity o f the mechanisms of differentiation and growth control o f the epithelia o f more common tumors such as those o f breast, colon and lung. It is thus possible that in a significant percentage o f carcinomas originated from the thyroid epithelium, and belonging to the same histotype, the presence o f detectable and com mon genetic lesion(s) could be identified and characterized. Moreover, if this concept is true, it should be expected that different genetic lesion(s) would differentiate the papillary and follicular carcinomas sharing a common his togenesis but different biological and clinical features.
