Cellulitis and Non-Suppurative Inflammation

Cellulitis

• Definition: Acute, diffuse, suppurative inflammation
• Cause: Streptococcus haemolyticus producing two enzymes
  • Fibrinolysin (streptokinase): Dissolves fibrin
  • Hyaluronidase (spreading factor): Dissolves hyaluronic acid of ground substance, aiding bacterial spread
• Sites: Loose connective tissues (e.g., subcutaneous tissue, scrotum, orbit, appendix wall)
• Characteristics:
  • Failure of localization due to lack of fibrin
  • Extensive necrosis
  • Pus is thin, often containing many red blood cells (sanguinous)
• Complications:
  • Acute lymphangitis and lymphadenitis
  • Blood spread (septicemia and toxemia)

Non-Suppurative Inflammation

• Catarrhal Inflammation: Mild acute inflammation of mucous membranes (respiratory and gastrointestinal tracts). Characterized by excess mucus secretion. Common examples include the common cold and bronchitis
• Pseudomembranous Inflammation: Severe acute inflammation causing a pseudo membrane on affected surfaces. Composed of necrotic cells, fibrin, and leukocytes. Examples include diphtheria and bacillary dysentery
• Fibrinous Inflammation: Inflammation marked by exudate rich in fibrinogen (e.g., lobar pneumonia)
• Serous, fibrinous, and serofibrinous inflammation: Inflammation involving serous sacs (pleura, peritoneum, pericardium). Characterized by excess serous exudates in the sac and fibrin deposition on the surfaces.

Hemorrhagic Inflammation

• Characterized by cellular exudate rich in red blood cells, caused by vascular damage
• Examples: smallpox, acute hemorrhagic pancreatitis

Allergic Inflammation

• An antigen-antibody reaction, typically leading to urticaria
• Characterized by abundant fluid exudates and eosinophils

Chronic Inflammation

• Characterized by:
  • Mild irritant with prolonged action
  • Gradual, prolonged tissue response
  • Often follows acute inflammation or starts as a slowly progressing chronic disease (e.g., tuberculosis, syphilis)
• Histopathological features:
  • End arteritis obliterans (E.A.O) of small arteries
  • Chronic inflammatory cells (lymphocytes, plasma cells, macrophages)
  • Fibrosis (a hallmark of chronicity)

Types of Chronic Inflammation

• Chronic non-specific inflammation: Different irritants produce similar inflammatory reactions (e.g., chronic non-specific cholecystitis)
• Chronic specific inflammation: Each irritant/organism causes a unique microscopic pattern called granuloma (e.g., tuberculosis, bilharziasis, leprosy)

Granuloma

• Definition: A chronic specific inflammation that forms a tumor-like mass, characterized by focal accumulation of many chronic inflammatory cells.
• Types:
  • Infective: Bacterial (tuberculosis, leprosy, syphilis), parasitic (bilharziasis, leishmaniasis), mycotic (e.g., madura foot), viral (subacute granulomatous thyroiditis)
  • Non-infective: Asbestosis, silicosis, foreign-body granulomas
  • Unknown cause: Sarcoidosis, Crohn's disease
• Histopathology:
  • Macrophages (tissue histiocytes, blood monocytes), lymphocytes, plasma cells, eosinophils
  • Granulation tissue
  • Fibrous tissue
  • Specific/foreign body components

This quiz covers the definitions, causes, characteristics, and complications of cellulitis as well as different types of non-suppurative inflammation. Understand the key terms like catarrhal and pseudomembranous inflammation and their clinical significance. Test your knowledge on the pathology and implications of these inflammatory conditions.