Abstract A22: Clinical implication of microscopic anthracotic pigment in mediastinal staging of non-small cell lung cancer by endobronchial ultrasound-guided transbronchial needle aspiration

Abstract

Abstract Introduction: Microscopic anthracotic pigment is frequently observed in EBUS-TBNA specimen from non-small cell lung cancer, but the clinical interpretation is not known. The aim of this study was to evaluate the clinical implication of microscopic anthracotic pigment in mediastinal staging of non-small cell lung cancer by EBUS-TBNA. Methods: From May 2010 to July 2011, Consecutive potentially operable non-small cell lung cancer patients who underwent EBUS-TBNA for mediastinal staging were recruited in this retrospective study. Results: Total 133 patients, male were 102 (76.7%). Median age was 68. Squamous cell carcinoma (59, 44.4%) and adenocarcinoma (57, 42.9%) were most common. Clinical stages after EBUS-TBNA were as followed; IA (18.8%), IB (17.3%), IIA (6.0%), IIB (9.0%), IIIA (36.8%), IIIB (12.0%). Total 281 mediastinal lymph nodes were sampled by EBUS-TBNA, station 4R (100, 35.8%) and station 7 (86, 30.8%) were most common sites. Malignant lymph nodes were 100 (35.8%). Microscopic anthracotic pigment was observed in 61 (21.7%) lymph nodes, and among them malignant lymph nodes were only 3 (P<0.001). The lymph nodes with microscopic anthracotic pigment were small (9.0 vs. 10.8 mm, P = 0.001) and low SUV on FDG-PET (5.4 vs. 6.7, P = 0.120). In multivariable analysis, microscopic anthracotic pigment was statistically significant associated with benign lymph node (adjusted OR, 14.3; 95% CI, 3.6–57.3; P<0.001). Conclusion: In potentially operable non-small cell lung cancer patients, microscopic anthracotic pigment in endobronchial ultrasound-guided transbronchial needle aspiration specimen was strongly associated with benign mediastinal lymph node.