Pathological diversity of pulmonary tuberculosis

Abstract

Tuberculosis (TB), a multi-systemic disease with myriad presentations and variable manifestations, is endemic in almost every part of the world and continues to remain the most common cause of infectious diseaserelated mortality and morbidity. The infection occurs most often via the pulmonary route through aerosols, producing pulmonary and/or extra-pulmonary disease. A remarkable feature of the organism M. tuberculosis is its ability to lie dormant within alveolar macrophages/granulomas that leads to active disease in 5–10% of immune-competent individuals; the endogenous reactivation usually causes abnormalities in the upper lobes of one or both lungs. Now, there has been a rise of progressive disease due to overt immune-suppression and emergence of drug-resistant strains. In the recent years, at autopsy, we have noted a definite affinity of the organisms for the intra-parenchymal bronchial tree with prominent or sole broncho-centric inflammation. The bronchial spread is often associated with consolidations (often in the lower lobes) and vasculitis. Many of the cases of miliary lesions are associated with diffuse alveolar damage and organizing pneumonia.