Diagnostic performance of EBUS-TBNA and its interrelation with PET-CT in patients with extra-thoracic malignancies

Introduction: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a well-established diagnostic tool for lung cancer, sarcoidosis, and suspected metastatic extra-thoracic malignancy (ETM). Patients with primary ETM often have hypermetabolic mediastinal/hilar lymph node enlargement in the PET-scan done for initial staging or post treatment follow-up. We aimed to determine the diagnostic performance of EBUS-TBNA and the relationship between PET-SUV values and diagnosis of malignancy metastasis in patients with ETM. Materials and Methods: Results of EBUS-TBNA in ETM patients with suspected MLN metastasis were retrospectively analysed (May 2016 to July 2019). Non-malign results were confirmed for surgery or clinical/radiological follow-up. Lymph nodes with a high FDG-uptake (SUV > 2.5, MLN) were reported as suspicious for metastasis. Results: Of the 588 EBUS procedures, 109 were included in the analysis. Patient' mean age was 62.5 +/- 10.1 years; there were 35 men and 74 women. Primary malignancies were breast cancer in 33, gastrointestinal in 23, female genital tract in 17, head and neck in 14, genitourinary cancer in 13, malignant melanoma in 6, sarcoma in 2 and kaposi sarcoma in 1. According to EBUS-TBNA smear and cell block histopathologic evaluations, 16 patients' results (14.7%) were malignant compatible with metastasis of ETM. Among the 93 patients with non-malignant diagnosis, EBUS-TBNA revealed a granulomatous lympadenitis compatible with sarcoid reaction in 7 and tuberculosis in 2. A total of 9 patients underwent surgical procedures after EBUS-TBNA, with a definitive histological diagnosis of granulomatous lymphadenitis in 2, malignancy in 5 and, reactive lymph node in 2. Overall sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of EBUS-TBNA were 76.19% (95% CI 52.83-91.78), 100% (95% CI 95.89-100.00), 100%, 94.62% (95% CI 89.12-97.12) and 95.4%, respectively. Conclusion: EBUS-TBNA sampling has high diagnostic performance. Histopathological confirmation requirement for MLN should be kept in mind in patients with ETM, even they have negative EBUS results.