Mohan V Frank, Nangia Vivek, Singh A K, Behl Rahul, Dumeer Nitin
Department of Pulmonary Medicine, Fortis Flt. Lt. Rajan Dhall Hospital, New Delhi, India.
Lung India. 2021 Mar-Apr;38(2):122-127. doi: 10.4103/lungindia.lungindia_128_20.
Diagnosis of isolated mediastinal tuberculosis (TB) can be challenging. Endobronchial ultrasound (EBUS) increases the diagnostic yield by direct sonographic visualization of mediastinal and hilar lymph nodes. With the advent of molecular techniques such as Gene Xpert, their addition to the cytology and cultures increases the diagnostic yield and detection of rifampicin resistance (RR) which helps change the effective therapeutic regimen immediately.
Prospective analysis of all patients undergoing EBUS-guided transbronchial needle aspiration (EBUS-TBNA) with a clinical possibility of TB in isolated mediastinal lymphadenopathy patients at a tertiary care referral center between June 2016 and January 2018. All patients had at least five passes from each node of which two passes from each lymph node sampled in 2 ml of saline for culture and Gene Xpert for microbiologic, pathologic, and molecular analysis as per hospital protocol.
Out of 60 patients, 44 were diagnosed to have mediastinal tuberculous lymphadenitis, 8 sarcoidosis, 2 malignancies, and 6 reactive lymphadenitis. TBNA cytology was positive in 40/44 patients (90.9%), out of which 18 patients were culture positive with the sensitivity of 100%, specificity 47.6%, positive predictive value (PPV) 45%, and negative predictive value (NPV) 100%, (P value 0.011). TBNA acid-fast bacilli (AFB) smear was positive in 20/44 patients (45.45%) out of which 12 were culture positive, with sensitivity of 67%, specificity 80.95%, PPV 60%, NPV 85% (P value 0.011). TBNA Gene Xpert was positive in 30/44 patients (68.2%), out of which 6 (13.63%) showed RR-TB and two were cytology negative. Sixteen patients where culture positive with sensitivity of 88.89%, specificity 66.67%, PPV 53.33%, NPV 93.33% (P value of 0.005). TBNA AFB culture was positive in 18/44 patients (40.9%).
EBUS-TBNA is an effective and safe diagnostic tool for intrathoracic TB, especially for mediastinal tuberculous lymphadenitis. The combination of various tests increases the diagnostic yield. Mediastinal nodal aspirates traditionally believed to be paucibacillary can still be captured by Gene Xpert.
孤立性纵隔结核的诊断具有挑战性。支气管内超声（EBUS）通过直接超声可视化纵隔和肺门淋巴结提高了诊断率。随着诸如Gene Xpert等分子技术的出现，将其应用于细胞学和培养可提高诊断率并检测利福平耐药性（RR），这有助于立即改变有效的治疗方案。
对2016年6月至2018年1月在一家三级医疗转诊中心因孤立性纵隔淋巴结肿大且临床怀疑结核而接受EBUS引导下经支气管针吸活检（EBUS-TBNA）的所有患者进行前瞻性分析。所有患者对每个淋巴结至少穿刺5次，其中从每个淋巴结穿刺2次，将样本采集于2ml盐水中用于培养，并按照医院方案进行Gene Xpert检测以进行微生物学、病理学和分子分析。
60例患者中，44例被诊断为纵隔结核性淋巴结炎，8例为结节病，2例为恶性肿瘤，6例为反应性淋巴结炎。44例患者中40例（90.9%）TBNA细胞学检查呈阳性，其中18例培养阳性，敏感性为100%，特异性为47.6%，阳性预测值（PPV）为45%，阴性预测值（NPV）为100%（P值0.011）。44例患者中20例（45.45%）TBNA抗酸杆菌（AFB）涂片呈阳性，其中12例培养阳性，敏感性为67%，特异性为80.95%，PPV为60%，NPV为85%（P值0.011）。44例患者中30例（68.2%）TBNA Gene Xpert检测呈阳性，其中6例（13.63%）显示RR-TB，2例细胞学检查为阴性。16例培养阳性，敏感性为88.89%，特异性为66.67%，PPV为53.33%，NPV为93.33%（P值0.005）。44例患者中18例（40.9%）TBNA AFB培养呈阳性。
EBUS-TBNA是诊断胸内结核尤其是纵隔结核性淋巴结炎的一种有效且安全的诊断工具。多种检测方法联合使用可提高诊断率。传统上认为纵隔淋巴结吸出物菌量少，但仍可通过Gene Xpert检测到。
