Positive PPD Test and TB-Ab Misdiagnosed as Tuberculosis Finally Proved as Sarcoidosis by Thoracoscopy: a Case Report

Background Tuberculosis (TB) is a common infectious disease in developing countries. Tuberculosis and sarcoidosis are difficult to differentiate. We report a case of a patient who was initially misdiagnosed as tuberculosis due to positive tuberculin test (PPD test) and tuberculosis antibody (TB-Ab), which was eventually proven as sarcoidosis by thoracoscopy. Methods Appropriate laboratory tests are carried out and a chest CT scan, bronchoscopy, thoracoscopic pathological biopsy were done. Results Serum sedimentation was increased and tuberculosis antibody was positive. The chest CT scan showed multiple pulmonary nodules in both lungs. The bronchoscopy demonstrated no abnormality. Thoracoscopic pathology showed noncaseating granulomas and acid-fast staining was negative. Conclusions When a patient has multiple pulmonary nodules and lymphadenopathy without obvious tuberculosis poisoning symptoms, physicians should pay attention to tuberculosis, sarcoidosis, and lung cancer. Pathology is crucial for the ultimate diagnosis.