Introduction: The significance of lymph node metastases and the optimal extent of lymphadenectomy remain matters of controversy in papillary thyroid cancer. This study was designed to assess the feasibility and reliability of OSNA and real-time PCR for CK19 and TG mRNA in papillary thyroid cancer lymph nodes evaluation compared to standard histopathology.

Material and methods: Each of 92 randomised lymph nodes from 32 papillary thyroid cancer patients were divided into representative parts and assessed using the three studied methods.

Results: Eighteen (19.6%) lymph nodes from ten (31.3%) patients were positive according to histopathology. When the cut-off value distinguishing metastatic from non-metastatic lymph nodes in the OSNA assay was set at 250 copies per microlitre, the results were positive in 16 (17.4%) lymph nodes from 11 (34.4%) patients. Twenty three (25%) lymph nodes were tested positive in real-time PCR for TG mRNA. Real-time PCR for CK19 mRNA was positive in 18 (19.6%) lymph nodes from 13 (40.6%) patients. No statistically significant differences were noted between the diagnostic accuracy of either molecular method compared to the histopathological examination (p = 0.81). Overall, 20 positive molecular biology results were noted in patients with negative histopathology results. Conversely, in 18 lymph nodes, despite a metastasis finding in histopathology, at least one molecular test yielded a negative result.

Conclusions: It was revealed that OSNA is a reliable technique for the evaluation of lymph node metastases in papillary thyroid cancer. This method was shown to have equivalent accuracy to histopathology and real-time PCR. (Endokrynol Pol 2014; 65 (6): 422–430)