INFLAMMATIONINFLAMMATION

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CellulitisCellulitis* Definition: Acute diffuse suppurative inflammation.

* Cause: Streptococcus haemolyticus. The organism

produces two enzymes:

(1) Fibrinolysin (streptokinase): Dissolves fibrin.

(2) Hyaluronidase (spreading factor): Dissolves

hyaluronic acid of ground substance helping spread of

bacteria and its toxins.

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* Sites: Loose connective tissue as subcutaneous tissue, scrotum, orbit and wall of the appendix. * Characters:1.Failure of localization because of absence of fibrin.2.Extensive necrosis.3.Pus is thin in consistency and may contain many RBCs i.e. sanguinous.

* Complications: 1.Acute lymphangitis and lymphadenitis. 2.Septic thrombophlebitis causing pyaemic abscesses.3.Septicaemia.

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II. NON-SUPPURATIVE INFLAMMATIONII. NON-SUPPURATIVE INFLAMMATION

1. Catarrhal Inflammation: 1. Catarrhal Inflammation:

Mild acute inflammation of the mucous

membranes of the respiratory and GIT

characterized by excess mucus secretion. e.g.

catarrhal rhinitis (common cold), bronchitis, ... etc.

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2. Membranous Inflammation 2. Membranous Inflammation (Pseudomembranous)(Pseudomembranous)

• Severe acute inflammation characterized by the

formation of a pseudomembrane on the affected

surface formed of necrotic cells, fibrin threads,

leucocytes. e.g. diphtheria and bacillary dysentery.

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3. Fibrinous3. Fibrinous Inflammation: Inflammation:

Characterized by an exudate rich in fibrinogen e.g.

lobar pneumonia.

4. Serofibrinous4. Serofibrinous Inflammation: Inflammation:

It involves serous sacs as pleura, peritoneum and

pericardium. Characterized by excess serous exudates

in the sac and deposition of fibrin on the surface.

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SerofibrinousSerofibrinous InflammationInflammation::

5. Hemorrhagic Inflammation:5. Hemorrhagic Inflammation:

Characterized by cellular exudate rich in the red

blood cells due to vascular damage e.g.

smallpox.

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6. Allergic Inflammation: 6. Allergic Inflammation:

as urticaria. It is an antigen antibody reaction

characterized by abundant fluid exudates and

eosinophils.

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CHRONIC INFLAMMATIONCHRONIC INFLAMMATION

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• Chronic inflammation is characterized by the

following:

1.The irritant is mild and has a prolonged action.

2. The tissue response is gradual and prolonged. 3.

Chronic inflammation may follow acute inflammation

or starts as slowly progressing chronic disease as in

tuberculosis and syphilis.

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4. Histopathologically it shows;

•End arteritis obliterans (E.A.O) of small arteries.

•Chronic inflammatory cells include lymphocytes,

plasma cells, macrophages.

•Fibrosis: which is the surest sign of chronicity.

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E.A.OE.A.O13

FibrosisFibrosis

Types of Chronic inflammation:Types of Chronic inflammation:1. Chronic non-specific inflammation: Different irritants

produce inflammatory reactions of the same non-specific

microscopic picture of chronic inflammation e.g. chronic non-

specific cholecystitis.

2. Chronic specific inflammation:

Each irritant or organism produces a characteristic

microscopic picture called granuloma e.g. tuberculosis,

bilharziasis and leprosy

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GranulomaGranuloma* Definition:

Chronic specific inflammation forming a tumor –

like mass grossly and characterized

microscopically by focal accumulation of large

number of chronic inflammatory cells.

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Pulmonary Tuberculosis

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* Types:

1. Infective granuloma:1. Bacterial as TB, leprosy & syphilis

2. Parasitic as bilharziasis & leishmaniasis

3. Mycotic (fungus) as madura foot, actinomycosis

4. Viral as granuloma inguinale

2. Non-infective granuloma:•As silicosis, asbestosis and foreign-body granuloma.

3. Unknown cause:

• Sarcoidosis, crohn’s disease17

* Histopathology of granuloma:

Macrophages main bulk of granuloma, made of tissue

histiocytes and blood monocytes.

Other inflammatory cells as lymphocytes, plasma cells,

eosinophils.

Granulation tissue.

Fibrous tissue.

Specific organism or foreign body.

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Foreign body granuloma to suture material (nylon, silk) contains multinucleated giant cells, with haphazardly arranged nuclei. These giant cells are fused macrophages. The foreign body is birefringent, and sometimes may be visible by polarized light in the middle of the granuloma or inside the giant cells.19

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Schistosomiasis

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