[2045] Concordance Study Reveals a Higher Performance of OSNA over Morphologic Techniques To Detect Lymph Node Metastasis in Papillary Carcinoma of the Thyroid

Sofia del Carmen, Sonia Gatius, Carmen Garcia-Macias, Juan Antonio Baena-Fustegueras, Guzman Franch-Arcas, Purificacion Galindo, Angustias Perez, Judit Pallares, Dolors Cuevas, Xavier Matias-Guiu, Enrique de Alava. Salamanca University Hospital-CIC-IBSAL, Salamanca, Spain; Arnau de Vilanova Hospital, Lleida, Spain

Background: Surgical treatment of papillary thyroid carcinoma (PTC) includes central compartment (CC) lymphadenectomy. This is positive in about one third of cases. Sentinel node biopsy of CC has a high positive predictive value. However, conventional intraoperative diagnostic assays have a 17% rate of false negatives. Lymph node (LN) analysis by means of One-Step Nucleic Acid Amplification (OSNA) assay is a procedure used for intraoperative staging of breast cancer patients, based on real-time amplification & quantitation of CK19 mRNA in LN samples. Since CK19 is also expressed in PTC, our aim is to determine utility of OSNA for intraoperative detection of LN metastasis of PTC in comparison with conventional morphologic intraoperative assays (cytology imprints (CYT) and H&E stain on completely serially sectioned (CSS) paraffin-embedded LN.
Design: We studied 186 consecutive LN in 17 patients with diagnosis of PTC. Each LN was weighted and bisected. One LN half was entirely submitted for OSNA. The other one was paraffin-embedded and CSS (which we considered as the gold standard). Two CYT were taken from each LN half and stained for H&E and CK19. We assessed: i) Concordance between CYT from both LN sides (H&E and CK19). ii) Concordance between CYT and CSS. iii) Sensitivity of OSNA and CYT with respect to CSS.
Results: i) 240 CYT from both sides were available for H&E staining; concordance was seen in all but 5 cases (97.9%). 238 pairs of CYT from both sides were available for CK19 staining; concordance was seen in all but 6 cases (97.4%).
ii) CCS was available in 49 cases. Concordance between CSS results and CYT results was seen in 45 cases (91.8%). In two cases, CSS was positive and CYT was negative. In another two cases CSS was negative and CYT was positive.
iii) Comparison between OSNA results and CYT could be performed in 180 LN. Concordant results were obtained in 156 LN (86.7%). In 16 LN (8.9%), positive OSNA results were obtained together with negative CYT. Negative OSNA results and positive CYT were obtained in 8 LN (4.4%); in 3 of them a low copy number of CK19 mRNA was seen, suggesting that the cutoff value for OSNA results in PTC could be lowered. Overall sensitivity of OSNA was 78.5%, above that of CYT (64.2%).
Conclusions: OSNA assay is feasible for intraoperative detection of lymph node metastasis of PTC. Its sensitivity is significatively higher than that of conventional intraoperative assays. Performance of CYT is in our hands similar to that of CSS to detect PTC.
Category: Techniques

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 299, Wednesday Morning

 

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