Granuloma and Tuberculosis

Granuloma

• Granuloma is a chronic specific inflammation.
• Granuloma is an organized collection of macrophages and other inflammatory cells around a pathogen in a circular form.
• Granulomas occur when the immune system tries to surround a pathogen that it can't eliminate.
• Granulomas cause necrosis and replacement of the original tissue by fibrosis.

Tuberculosis

• Tuberculosis is a chronic infective granuloma caused by tubercle bacilli (Mycobacterium tuberculosis).
• Tuberculosis can be contracted by inhalation from coughing or sneezing of active TB patients.
• Tuberculosis can be contracted by ingesting contaminated milk.
• M. tuberculosis can reproduce inside macrophages.
• Macrophages are unable to present antigen to lymphocytes.
• Bacteria can become dormant, resulting in latent infection.
• If bacterial antigens are presented to lymphocytes by macrophages, an immune response is activated with cytokines production and tissue necrosis.
• Risk groups for tuberculosis include those with AIDS, those who are malnourished, those in close contact with active patients, smokers and alcoholics.
• Symptoms of tuberculosis include chronic cough (hemoptysis), fever, night sweats, and weight loss.
• The historical term "consumption" came about due to the weight loss associated with tuberculosis.
• The "Mechanisms of caseation" (causes) are Hypersensitivity and Ischemic necrosis.
• Hypersensitivity occurs between lymphokines secreted by T lymphocytes/Macrophages and the antigen of tubercle bacilli (tuberculoprotein).
• Ischemic necrosis is due to endarteritis obliterans.

Tubercle

• A tubercle is the basic unit of tuberculosis.
• A tubercle is a microscopic structure consisting of a collection of chronic inflammatory cells, caseation necrosis, and fibrosis around the tubercle bacilli.
• A tubercle is considered the reaction of tissues against TB bacilli.

Immunity & Hypersensitivity in TB

• Immunity is cell-mediated through macrophages, epithelioid cells, and giant cells, which engulf the bacteria and try to prevent spread (Tubercle formation).
• Hypersensitivity is due to lymphokines secreted by sensitized T lymphocytes/Macrophages, causing caseation necrosis.

Primary Pulmonary Complex

• The triad consists of Ghon's focus, tuberculous lymphangitis, and tuberculous lymphadenitis of the regional lymph nodes.

Secondary Pulmonary Tuberculosis

• Secondary pulmonary tuberculosis is a second infection or reactivation.
• Secondary pulmonary tuberculosis is an adult type of tuberculosis.
• Secondary pulmonary tuberculosis shows apical cavitation.
• Lymph nodes are not involved.
• Hemoptysis can occur, which is coughing of blood.
• Pneumothorax, or air in the pleura, can occur.
• Right-sided heart failure can result from lung fibrosis.
• Amyloidosis, or the deposition of insoluble protein, can occur.

Intestinal Tuberculosis

• Intestinal tuberculosis has a primary intestinal complex.
• Tubercles are at payer's patches.
• TB Ulcers can occur.
• Tuberculous lymphangitis, Tabes mesenterica and Fate are all associated with this condition.

Secondary Intestinal Tuberculosis

• Tubercles in Peyer's patches occur at the terminal ileum.
• Tuberculous ulcers are multiple and have undermined edges, a soft caseous floor, and are transverse and heal by fibrosis.
• No lymphangitis or lymphadenitis is associated.

Tuberculous Peritonitis

• Tuberculous peritonitis is a secondary type of tuberculosis that occurs commonly in children.
• The wet or ascetic type's reaction is mainly exudative.
• The dry or adhesive type's reaction is mainly proliferative (cellular-tubercle forming).

Pott's Disease

• Pott’s disease is secondary, spread by blood.
• This disease affects the cervical, thoracic, and lumbar spine.
• Pathological features include kyphosis, cold abscess, and paraplegia.