Tuberculosis PDF

TUBERCULOSIS [Document subtitle] BASANT Granuloma Granuloma is a chronic specific inflammation. It is an organized collection of macrophages and other inflammatory cells arranged in a circular form around a pathogen. Granuloma forms when the immune system attempts to contain a pathogen th...

TUBERCULOSIS [Document subtitle] BASANT Granuloma Granuloma is a chronic specific inflammation. It is an organized collection of macrophages and other inflammatory cells arranged in a circular form around a pathogen. Granuloma forms when the immune system attempts to contain a pathogen that it cannot eliminate. This process often leads to tissue necrosis and replacement of the original tissue by fibrosis. Tuberculosis (TB) Tuberculosis is a chronic infective granuloma caused by the bacteria Mycobacterium tuberculosis (tubercle bacilli). Methods of Infection: Inhalation: By coughing or sneezing of an active TB patient. Ingestion: Through contaminated milk. Host-Bacteria Interaction in Tuberculosis: M. tuberculosis can reproduce inside macrophages. Macrophages may fail to present antigens to lymphocytes. Bacteria can become dormant, resulting in latent infection. If macrophages successfully present bacterial antigens to lymphocytes, the immune response is activated, leading to cytokine production and tissue necrosis. Risk Groups and Symptoms: Risk Groups: AIDS patients. Individuals living in overcrowded conditions. Malnourished individuals. Close contacts of active TB patients. Smokers and alcohol users. Symptoms:  Chronic cough (hemoptysis). Fever. Night sweats. Weight loss (historically referred to as "consumption" due to the severe weight loss). Mechanisms of Caseation (Causes): 1. Hypersensitivity: o Caseation occurs due to the interaction between lymphokines secreted by T lymphocytes/macrophages and the antigens of tubercle bacilli (tuberculoprotein). 2. Ischemic Necrosis: Caused by endarteritis obliterans, which leads to reduced blood supply and tissue death. Tubercle (Tuberculous Granuloma) Definition: The tubercle is the basic structural unit of tuberculosis. Microscopic Structure: o Composed of chronic inflammatory cells, including macrophages and lymphocytes. o Includes areas of caseation necrosis and fibrosis surrounding tubercle bacilli. Significance: o Represents the tissue's immune reaction to Mycobacterium tuberculosis. Associated Features: o Caseating Tubercle: Contains areas of caseation necrosis at the center. o Langhans Giant Cell: A characteristic multinucleated giant cell seen in tuberculous granulomas, formed by the fusion of macrophages. Miliary Tuberculosis Definition: A disseminated form of tuberculosis where a large number of  Mycobacterium tuberculosis bacteria spread through the bloodstream, leading to widespread infection throughout the body. Immunity and Hypersensitivity in TB 1. Immunity: o Mediated by macrophages, epithelioid cells, and giant cells. o These cells engulf the bacteria and attempt to limit its spread by forming tubercles. 2. Hypersensitivity: o Caused by lymphokines secreted by sensitized T lymphocytes and macrophages. o Results in caseation necrosis, a hallmark of tuberculosis. Primary Tuberculosis Ghon's Focus: The initial site of infection in the lung, typically subpleural. Primary Complex: Consists of: 1. Ghon’s focus. 2. Lymphangitis. 3. Tuberculous lymphadenitis of the regional lymph nodes. Primary Pulmonary Complex The triad includes: 1. Ghon’s focus. 2. Tuberculous lymphangitis. 3. Tuberculous lymphadenitis of nearby lymph nodes. Secondary Pulmonary Tuberculosis  Definition: Results from reinfection or reactivation of dormant bacteria. Commonly seen in adults. Features: o Localized to the apices of the lungs (apical cavitation). o Lymph nodes are not involved. o Symptoms: ▪ Hemoptysis (coughing up blood). ▪ Pneumothorax (air in pleural space). ▪ Right-sided heart failure due to lung fibrosis. ▪ Amyloidosis (deposition of insoluble proteins). Intestinal Tuberculosis 1. Primary Intestinal Tuberculosis: o Infection from ingestion of contaminated milk or food. o Primary Intestinal Complex: ▪ Tubercles in Peyer’s patches. ▪ TB ulcers. ▪ Tuberculous lymphangitis. ▪ Tabes mesenterica (tuberculous mesenteric lymphadenitis). 2. Secondary Intestinal Tuberculosis: o Results from swallowed sputum in pulmonary TB. o Involves tubercles in Peyer’s patches at the terminal ileum. Fate of Intestinal Tuberculosis  Progression to ulcers with undermined edges and a caseous floor. Healing occurs through fibrosis. Secondary Intestinal Tuberculosis Location: o Tubercles form in Peyer’s patches at the terminal ileum. Tuberculous Ulcers: o Features: a) Multiple. b) Undermined edges. c) Soft caseous floor. d) Transverse orientation. e) Heal by fibrosis. Key Characteristics: o No lymphangitis or lymphadenitis associated. Tuberculous Peritonitis Definition: o A secondary form of tuberculosis that primarily affects children. Types: 1. Wet or Ascitic Type: ▪ Reaction is predominantly exudative. ▪ 2. \Dry or Adhesive Type: ▪ Reaction is mainly proliferative, with tubercle formatin Pott’s Disease (Spinal Tuberculosis) Cause: o Secondary spread of tuberculosis through the bloodstream. Common Sites: o Cervical, thoracic, and lumbar vertebrae.  Pathological Features: o Kyphosis: Forward curvature of the spine. o Cold Abscess: Non-pyogenic abscess formation. o Paraplegia: Paralysis due to spinal cord compression. o