Ret oncogene protein expression in papillary thyroid carcinoma and relatedlesions

Background: Activation of net oncogenes, particularly Ret/PTC, has been ide ntified in papillary thyroid carcinoma (PTC), The purpose of this study was to investigate the immunostaining pattern of:Ret oncogene protein in PTC a nd nodular non-PTC lesions with a fine chromatin pattern. Materials and methods: Ninety-three PTC and 139 nodular non-PTC lesions wer e microscopically reviewed to identify the nuclear changes of "limited nucl ear features of PTC" (focal nuclear grooves, nuclear inclusions or opticall y clear nuclei) and areas of infiltrating carcinoma (IC) and were submitted for immunostaining with Ret oncogene protein antiserum. Results: Immunoreactivity for net protein ranged from negative in follicula r adenoma (FA) with a coarse chromatin pattern, to negative or weak reactiv ity in FA with a fine chromatin pattern, to strong reactivity in PTC with a reas of infiltrating carcinoma (IC). In FA with fine chromatin, FA and foll icular carcinoma (FC) containing an admixture of areas of coarse and fine c hromatin, areas with nuclear changes with "limited nuclear features of PTC" displayed varying degrees of immunoreactivity. The intensity of immunostai ning varied with the degree of nuclear change. The noninvasive component of PTC with IC usually showed more extensive and stronger reactivity than PTC without IC, PTCs with and without IC were associated with a rate of lymph node metastasis of 48% and 3%, respectively. Conclusions: The expression of Ret oncogenes (Ret/PTC, other unknown varian ts or wild type) is focally or extensively present in all PTC with IC,The d egree of immunoreactivity is likely to be proportional to the potential for lymph node metastasis of PTC. In the context of this study and due to the specificity of Ret oncogenes, it is likely that nodular non-PTC lesions wit h a fine chromatin pattern and focal positive reactivity for Ret oncogene r epresent PTC-related lesions.