Detection of cytokeratin 20 mRNA in thyroid carcinomas and peripheral blood by RT-PCR

Background and aim: Despite a variety of diagnostic tools, diagnosis of thy roid carcinoma remains difficult. A differentiation between benign and mali gnant thyroid diseases is however essential for operative decision making. The aim our study was to investigate a nested RT-PCR system to detect Cytok eratin 20 (CK 20) in benign and malignant thyroid tissues and peripheral bl ood. Methods: Frozen tissue sections of 33 thyroid carcinomas and 30 benign thyr oid diseases (14 multinodular goiters, 14 follicular adenomas, 2 Hashimoto' s thyroiditis) were obtained intraoperatively. Blood samples were drawn fro m 27 patients with thyroid carcinomas, 9 patients with benign thyroid disea ses and 7 healthy volunteers. Results: 100% of the medullary, 70% of the follicular, 27% of the papillary and 25% of the anaplastic carcinomas showed an expression of CR 20 mRNA in the examined frozen tissue sections. CK 20 mRNA was undetectable in 30 ben ign thyroid diseases. Circulating tumor cells were found in the peripheral blood of 2/4 patients with medullary, 2/7 with follicular, 1/13 patients wi th papillary and 1/3 patients with anaplastic thyroid carcinomas. CK 20 mRN A could not be detected in blood samples of patients with benign thyroid di seases and healthy volunteers. Conclusion: CK 20 transcripts can be detected sucessfully in tissue section s of thyroid carcinomas but not in benign thyroid diseases. Moreover the in vestigated CK 20 RT-PCR system is able to detect circulating tumor cells of thyroid carcinomas in the peripheral blood.