EUS-FNA for the Diagnosis of Tuberculosis and Sarcoidosis

Abstract

Background: Other than malignancy mediastinal lymphadenopathy may indicate benign diseases such as pulmonary tuberculosis (TB) and sarcoidosis, which are more frequently found in ethnic subgroups. Differentiation between sarcoidosis, tuberculosis and other diseases can be difficult, if standard diagnostic methods such as bronchoscopy and sputum analysis fail. Endoscopic ultrasound guided fine-needle aspiration (EUS-FNA) of mediastinal nodes has proven to be highly sensitive and specific in the diagnosis of lung cancer. It can provide material for cytology and bacteriology but it remains unknown whether this is sufficient to differentiate between TB and sarcoidosis. Methods: Prospective study including 72 consecutive patients (Mean: 50.2 years; 36 male) with mediastinal lymphadenopathy but no suspicion of lung cancer or other malignancy on CT. All had negative investigations including bronchoscopic biopsy and bronchoalveolar lavage before EUS-FNA was carried out with at least two passes using a 22gauge needle. Cytology and microscopy for acid-fast bacilli was performed by independent physicians and material sent for TB culture. At least 9 months of clinical follow-up was undertaken to exclude TB in non-TB cases. Results: Adequate samples were obtained in 71/72 patients and no complications occurred. Cytology suggested TB in 24 cases and sarcoidosis in 33. Malignancy was found in 4 patients (n=2 lymphoma, n=2 metastatic cancer); in the remaining 10 cases, 2 abscesses and 8 non-specific inflammatory changes were found. Culture revealed TB in 20 cases. A final diagnosis of TB was made in 27 patients after at least 9 months' follow-up; of these 3 had negative cytology but positive culture. The final diagnosis of sarcoidosis was made in 30 cases; the remaining 3 with cytology suggesting sarcoidosis were proven to have TB on EUS-FNA culture. The sensitivity and specificity of EUS-FNA for TB were 0.89 and 1.0 respectively; those for sarcoidosis were 1.0 and 0.93. EUS-FNA achieved a correct diagnosis in 63/72 patients (88%). In 8 of these with non-specific inflammation no significant diagnosis was found. Lymphadenopathy was due to old TB and smoking. Conclusion: EUS-FNA cytology combined with culture offers an excellent method for the differential diagnosis of TB and sarcoidosis, which had not been diagnosed by traditional methods.