Tuberculosis and sarcoidosis are chronic systemic diseases that have similar pulmonary and extra-pulmonary manifestations. It is likely that infection with Mycobacterium tuberculosis (MTB) is a common pathophysiologic mechanism for tuberculosis and sarcoidosis. We present a case of a patient with a primary diagnosis of sarcoidosis. The patient did not receive any immunosuppressive treatment till that time. Subsequently, smear-negative pulmonary tuberculosis was discovered, confirmed with the positive culture of bronchial washings and treated with antituberculous agents without major side effects. Both sputum smears and cultures were negative at the end of the treatment. It is worth highlighting that these two diseases share both clinical and histopathological features. Though it can be genuinely challenging to distinguish them, the precise and rapid diagnosis is crucial because the treatment is so different. Therefore MTB infection should be kept in mind in a broad differential diagnosis.
Keywords: differential diagnosis; sarcoidosis; tuberculosis.