The critical role of EBUS-TBNA cytology in the staging of mediastinal lymph nodes in lung cancer patients: A correlation study with positron emission tomography findings

BACKGROUND: The sensitivity and specificity of positron emission tomography (PET) have been significantly improved for the identification of malignancies in recent years; however, it is still necessary to confirm PET findings in a lymph node (LN) by direct tissue sampling. Endobronchial ultrasound–guided transbronchial needle aspiration (EBUS-TBNA) is the most commonly used approach for diagnosing and staging mediastinal LNs, particularly in lung cancer patients with locally advanced disease. Despite this fact, evidence-based studies of EBUS-TBNA cytology and PET findings are still suboptimal. METHODS: The electronic database at the Johns Hopkins Medical Institutions and the pathology archives were searched to identify patients with mediastinal lymphadenopathy who had both EBUS-TBNA mediastinal LN sampling and a PET scan over a 14-month period. Patients suspected of having lung cancer and patients with a history of lung cancer were included in this study. Cytological diagnoses and follow-up surgical LN diagnoses were reviewed and correlated with PET scan findings. RESULTS: A total of 140 LNs from 79 patients, including 86 PET-positive LNs and 54 PET-negative LNs, were included. The most frequently sampled LNs were 4R and 7. The average size of PET-positive and PET-negative LNs was 1.2 and 1.6 cm, respectively. Among PET-positive LNs, 41.9% were malignant, 41.9% showed reactive changes or granulomatous inflammation, and 9.3% were nondiagnostic by EBUS-TBNA. However, among PET-negative LNs, 74.1% showed reactive changes or granulomatous inflammation, 7.4% were malignant, and 18.5% were nondiagnostic by EBUS-TBNA. CONCLUSIONS: The data demonstrate that EBUS-TBNA cytology improves the diagnostic accuracy of mediastinal LNs and clinical staging. Furthermore, EBUS-TBNA may identify additional malignant LNs (7.4%), and this highlights the risk for false-negative findings with PET scanning in isolation. Cancer Cytopathol 2017;125:717-25.