Histological diagnosis of culture, smear and polymerase chain reaction (PCR) negative pulmonary tuberculosis

• DOI: 10.1016/j.ejim.2013.08.579
• Publication Date: 2013-10-11T03:28:31Z
• Authors: M. Sousa; C. Canelas; I. Fontoura; B. Rodrigues; J. Lemos; A. Vaz; S. Torres; F. Girão
• Keywords: Gold standard (test); Sputum culture; GeneXpert MTB/RIF

Introduction: Early diagnosis and treatment of tuberculosis (TB) are critical to effective patient management and TB control. Clinical screening, radiological exams and smearmicroscopy are often the first approaches, but the gold standard is still the cultural isolation of the Mycobacterium tuberculosis. Currently, newmolecular assays are being tested and developed. However, in some patients, the laboratory diagnosis is never obtained. Case reports:We report 4 recent cases, 2 women and 2 men, with an average age of 48 years. One patient was immunocompromised. 3 patients had symptoms, 2 with cough and sputum, and 1 with dry cough. X-ray was normal only in one patient. Chest-CT evidenced changes in all cases, suggestive of TB in 3 of them. Adenosine deaminase (ADA) was measured and presented a raised value in 2 cases. In the 2 patients with sputum, its analysis with smear, polymerase chain reaction (PCR) and culture was negative for TB. All patients were submitted to bronchoscopy with washing; broncoalveolar lavage was performed in two. The smear, PCR and culture for TB were negative in all of these specimens. The diagnosis was established by biopsy in all cases: surgical in 2 (histological features), transthoracic in 1 (culture of the tissue positive for TB) and bronchial in 1 (histological features). All patients were submitted to tuberculostatic treatment. Conclusions: In most cases, the diagnosis of TB is challenging and time consuming, and relays on combination of different methods. In the cases presented, despite the access to bronchial secretions, an invasive approach by biopsy was required to establish the diagnosis. Histology is usually used only in non pulmonary forms of TB and further research is needed to evaluate its accuracy in this type of cases.