Morphologic Patterns of Inflammation

]]Acute Inflammation]]

  • dilation of small blood vessels
  • accumulation of leukocytes and fluid in the extravascular tissue

\ Classification according to the morphologic appearance:

  • Non-suppurative Inflammation   * Catarrhal inflammation   * Serous inflammation   * Fibrinous inflammation   * Hemorrhagic inflammation   * Membranous/pseudo-membranous inflammation   * Necrotizing (gangrenous) inflammation   * Allergic inflammation
  • Suppurative Inflammation   * Localized:     * Abscess inflammation     * Furuncle     * Carbuncle   * Diffuse:     * Cellulitis

]]Acute Non-suppurative Inflammation]]

  • without pus formation
Catarrhal inflammation
  • excessmucussecretionduetoinflammationofmucusmembranesexcess mucus secretion due to inflammation of mucus membranes

^^Site^^: mucous membranes

%%Example%%: common cold (rhinovirus), influenza

@@Gross appearance:@@ congestion, edema, mucus secretion

==Microscopic examination: ==

  • blood vessel dilation, congested (filled with blood)
  • excess mucus on epithelial surface
  • few or absence of neutrophils

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Serous Inflammation

 

  • wateryprotein−poorfluidwatery protein-poor fluid (effusion)
  • typically does not contain microbes or large numbers of leukocytes
  • Derived from:   * serum   * mesothelial cell secretion

^^Site^^: spaces created by cell injury or into body cavities lined by the peritoneum, pleura, or pericardium.

%%Examples%%: skin blister (burn), pleural effusion (pleurisy)

@@Gross appearance@@: congested surface, watery effusion

Fibrinous Inflammation
  • fibrinousexudatefibrinous exudate

^^Site^^: lining of body cavities, (meninges, pericardium, and pleura)

%%Example%%: serosal surfaces (fibrinous pericarditis)

 

Hemorrhagic Inflammation
  • exudaterichinredbloodcellsexudate rich in red blood cells

%%Example%%: severe capillary damage (anthrax, plague)

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Membranous/Pseudo-membranous Inflammation
  • necroticmembraneonmucussurfacesnecrotic membrane on mucus surfaces

%%Example%%: diphtheritic pharyngitis, bacillary dysentery

@@Gross appearance@@: greyish membrane on mucosal surface

==Microscopic examination: ==

  • necrotic mucosa
  • fibrin and inflammatory cells adherent to mucosal surface

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Necrotizing (Gangrenous) Inflammation

%%Example%%: gangrenous acute appendicitis, gangrene of the foot

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Allergic Inflammation

%%Example%%: bronchial asthma

==Microscopic examination: ==

  • exudate rich in eosinophils
  • extensive edema

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]]Acute Suppurative (Purulent) Inflammation]]

  • purulent exudate (pus): fluid, necrotic cells, and pus cells (dead neutrophils)
Localized
  • abscess formation

==Organisms==: pyogenic bacteria (Staphylococcus aureus)

Diffuse

<strong>Cellulitis</strong><strong>Cellulitis</strong>: diffuse suppurative inflammation

^^Site^^: subcutaneous tissue (orbit, pelvis, scrotum, mediastinum)

==Organisms==: Streptococcus hemolyticus

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<<Chronic Inflammation<<

  • Chronic “non-specific” or diffuse inflammation
  • Chronic specific inflammation

<<Diffuse Non-specific Inflammation<<

  • diffuse chronic inflammatory cell infiltrate

%%Example%%: chronic pyelonephritis, chronic cholecystitis

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<<Chronic Specific Inflammation (Granuloma)<<

  • caseating granulomatous inflammation   * %%Example%%: Tuberculosis
  • non-caseating granulomatous inflammation   * %%Example%%: leprosy, syphilis, schistosomiasis, sarcoidosis and foreign body granuloma

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