Ultrasound guided fine needle aspiration biopsy in mediastinal tuberculosis

SETTING: Diagnosis of mediastinal tuberculosis (TB) is difficult due to non-specific clinical features and lack of characteristic radiographic features. Histopathological confirmation has often required computed tomography guided fine needle aspiration biopsy (FNAB) or even invasive procedures such as mediastinoscopy or open/surgical biopsy. FNAB under ultrasound (US) guidance can also be performed in this clinical setting. OBJECTIVE: To define the role of percutaneous US guided FNAB in the diagnosis of mediastinal tuberculosis. DESIGN: Twenty-six patients with a proven diagnosis of mediastinal TB formed the study group. Chest radiographs and sputum examination were negative. FNAB was performed via suprasternal (n = 20) and parasternal (n = 6) route under sonographic guidance using 22G spinal needle. Aspirates were considered positive for TB when epithelioid cell granuloma with caseation necrosis and/or the presence of Mycobacterium tuberculosis by acid-fast bacilli (AFB) or culture was demonstrated, indeterminate when epithelioid cell granulomas were seen but without caseation necrosis or AFB, and negative when aspirate contained non-representative material. RESULTS: A total of 30 biopsies were performed in the 26 patients, including repeat biopsy and biopsy of different sites in two patients each. FNAB was positive for TB in 20 of the 26 patients. In four, AFB were demonstrated, and in seven culture was positive for M. tuberculosis; in the remaining six patients, cytologic diagnosis was indeterminate in four and negative in two. No procedure related complications were noted. CONCLUSION: Ultrasound guided FNAB is a safe, effective technique in the diagnosis of mediastinal TB.