Expression of oncofetal fibronectin messenger ribonucleic acid in fibroblasts in the thyroid: A possible cause of false positive results in molecular-based diagnosis of thyroid carcinomas

Oncofetal fibronectin (onfFN) messenger ribonucleic acid (mRNA) is abundant ly expressed in thyroid papillary and anaplastic carcinomas. These carcinom as can be preoperatively diagnosed by the detection of onfFN mRNA. in fine needle aspiration biopsies (FNABs). However, previous reports have noted th at the expression of onfFN mRNA was observed in 3.7% of the FNABs that were diagnosed as negative cytology. To clarify this discrepancy, we examined t he expression of onfFN mRNA in fibroblasts in the thyroid. By RT-PCR and re al-time quantitative RT-PCR analyses, we detected a high copy number of onf FN mRNA in cultured fibroblasts obtained from the normal thyroid tissues di ssected surgically. Thus, we conclude that the contaminated fibroblasts in FNABs due to tumor necrosis or acute or chronic inflammation may be a cause of false positive results in molecular-based diagnosis of thyroid carcinom as.