INFLAMMATION 1

Cellulitis * 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. 2

* 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. 3

II. 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. 4

2. Membranous Inflammation (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. 5

3. Fibrinous Inflammation: 3. Fibrinous Inflammation: Characterized by an exudate rich in fibrinogen e.g. lobar pneumonia. 4. Serofibrinous Inflammation: 4. Serofibrinous 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. 6

7 Serofibrinous Inflammation:

5. Hemorrhagic Inflammation: 5. Hemorrhagic Inflammation: Characterized by cellular exudate rich in the red blood cells due to vascular damage e.g. smallpox. 8

6. Allergic Inflammation: as urticaria. It is an antigen antibody reaction characterized by abundant fluid exudates and eosinophils. 9

CHRONIC INFLAMMATION 10

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. 11

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. 12

E.A.O 13 Fibrosis

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 14

Granuloma * Definition: Chronic specific inflammation forming a tumor – like mass grossly and characterized microscopically by focal accumulation of large number of chronic inflammatory cells. 15

Pulmonary Tuberculosis 16

* 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 disease 17

* 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. 18

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

20 Schistosomiasis

21 Thanks