Endobronchial ultrasound sonographic characteristics of mediastinal lymph node in evaluation of lung cancer

Abstract

Endobronchial ultrasound (EBUS) and contrast enhanced computed tomography (CECT) are essential components of lung cancer evaluation. Features of mediastinal lymph nodes on EBUS and CECT can help in predicting metastatic disease. Clinical, radiological and EBUS data of patients with clinico-radiological suspicion of lung cancer and have undergone EBUS with no trans-bronchial needle aspiration (TBNA) or nonyielding EBUS-TBNA were retrospectively collected from medical records. EBUS features of lymph nodes for metastatic disease [Size >1cm, round shape, heterogeneous echo-texture, indistinct margin, coagulation necrosis(CN), absence of central hilar structures (CHS) and grade II-III vascularity] were noted. CECT findings were noted from CECT films and reports to analyse and compare with EBUS findings. Scoring criteria of EBUS sonographic characteristics from previous studies for discriminating benign and malignant lymph-nodes were also assessed for possible prediction. Thirty-one (31) patients [male=18 (58.1%), female=13 (41.9); age (mean±SD) =52.9±15.7 years] with CECT findings suggesting lung cancer were studied. EBUS showed mediastinal lymphadenopathy at 82 lymph node station in 29 patients. Size>1cm, round shape, heterogeneous echo-texture, distinct margin, CN, absence of CHS and grade II-III vascularity at 33 (40%), 28 (34%), 31 (38%), 55 (67%), 3 (4%), 77 (94%) and 6 (7.3%) lymph nodes, respectively. Malignant or benign status assigned to lymph nodes using different scoring criteria were highly discordant. Compared to EBUS, CECT revealed abnormal mediastinal lymph nodes (LN) in significantly less number of patients [21( 67.7%) vs 29 (93.5%), p=0.01] involving less number of lymph node stations (LNS) [(37 vs 82, p<0.001]. Lymphadenopathy frequency at different LNS on EBUS and CECT showed a weak positive but significant correlation (r=0.356; p=0.0426). EBUS characteristics and related scores have limited accuracy in differentiating benign and malignant nodes. CECT underestimates lymph-adenopathy in comparison to EBUS. Larger prospective study of EBUS features with cyto/histo-pathology correlation may elicit its clinical significance and help to create a better and composite scoring criteria.