A PA view is shown here. His chest radiograph demonstrates a complete opacification of the right hemithorax with a shift of the mediastinal structures to the left. The mycobacteria usually deposit in the middle or lower lobes, where they undergo phagocytosis and multiply intracellularly. As neutrophils arrive, tubercles are formed and the phagocytized tubercles are carried to regional lymph nodes. During this stage, there are both lymphatic and hematogenous dissemination, as the primary focus of infection becomes encapsulated and eventually calcifies.
Hypersensitivity develops over a period of two to ten weeks.
In the majority of cases, surviving mycobacteria remain dormant. Postprimary TB involves the reactivation of dormant bacilli which occurs with episodes of immunosuppression, malnutrition, or debilitation, typically within two years following exposure. Primary and postprimary TB differ clinically, pathologically, and radiologically. Parenchymal disease 2. Pleural effusion 5.