FORMS OF INFLAMMATION 

FORMS OF INFLAMMATION 

GOALS

• Know how to define acute inflammation, chronic inflammation
• To be able to define and give an example for the different morphological varieties of acute and chronic inflammations 

Plan 

I. Introduction

 1. Definitions/generalities

 2. Interest of the question

II. Acute inflammation 

      II.1. The different forms of acute inflammation

III. Chronic inflammations

      III.1. Chronic granulomatous inflammations 

      III.2. chronic non-granulomatous inflammations 

IV. Comparative table between acute and chronic inflammation

V. Conclusion

FORMS OF INFLAMMATION

I – Introduction:

1. Definitions/generalities: 

• Inflammation or inflammatory reaction is the response of living, vascularized tissues to an exogenous or endogenous aggression.
• Inflammation is usually a beneficial process: its purpose is to eliminate the pathogen and repair tissue damage.
•  Sometimes inflammation can be harmful
• Three phases:

 1 – Vasculo-exudative phase 

 2- Cellular and productive phase

 3- Repair and healing phase 

• Depending on: 

– the predominance of one of these phases               

– the evolutionary modalities of inflammations                          

• Acute inflammation  : where the vasculo-exudative phase predominates. Exp.: acute appendicitis.
• Chronic inflammation: defined by the persistence of the reaction and the development of fibrosis. Exp. Pulmonary fibrosis
• 
• The term subacute inflammation is attributed either to acute inflammation in the process of healing or to acute inflammation evolving towards chronicity. 
• This term should be avoided because it does not correspond to a precise anatomo-clinical  picture .

2. Interest: 

• Frequency
• Multiplicity of causes
• Examination under an optical microscope allows us to date the inflammation and determine the mode of development (acute or chronic nature):
• Diagnostic orientation: look for an etiology: specific granulomatous inflammation

II- Acute inflammation 

    Acute inflammation represents the immediate response to an aggressive agent, of short duration (a few hours or a few days): 

• Rough installation 
• Intense vasculo-exudative phenomena:

 – Extravasation of fluid and plasma proteins: edema

 -Intervention of polymorphonuclear neutrophils

• Resolution in a few days 

II.1. Forms of acute inflammation:

There are several forms of acute inflammation:

1. Congestive inflammation 
2. Edema inflammation
3. Hemorrhagic inflammation
4. Fibrinous inflammation
5. Thrombotic inflammation 
6. Purulent or suppurative inflammation
7. Gangrenous inflammation

 a-Congestive inflammation

• very heavy congestion
• quickly resolvable
• Example;

      * solar erythema

       *congestive colitis

b-Edematous inflammation 

• It is characterized by a particularly abundant exudate.
• Examples:

• allergic reaction (type I hypersensitivity)

• acute pulmonary edema during viral infection 

c-Hemorrhagic inflammation 

FORMS OF INFLAMMATION

• Extravasation of red blood cells (erythrodiapedesis) 
• Examples:

•  viral infections (pneumonia, encephalitis, etc.) 
• purpura of meningococcal septicemia 
• acute attack of ulcerative colitis 

d-Fibrinous inflammation

• It is characterized by an exudate very rich in fibrinogen which coagulates into a fibrin network.
• Macroscopy: whitish filaments “false membranes”

e-Thrombosing inflammation 

• Blood clots blocking small veins and arteries 
• direct injury to the vascular walls or endocardium.
• Examples:
•  systemic vasculitis 
•  infective endocarditis 
•  microscopy: Eosinophilic fibrin deposits

f- Purulent or suppurative inflammation

• massive presence of pyocytes (altered polymorphonuclear cells)
• so-called pyogenic bacteria (staphylococcus, streptococcus, etc.)
• several forms:

•  Pustule: accumulation of pus in the thickness of the epidermis or under the detached epidermis
• Abscess: localized suppurative inflammation creating a cavity in a solid organ 
•  Phlegmon: diffuse, uncircumscribed suppuration, extending along the tendon sheaths, or in the connective tissue between the aponeuroses and between the muscle bundles of the limbs.
•  Empyema: suppuration collected in a pre-existing natural cavity. 

For example: serous cavities, joints (arthritis), sinuses (sinusitis), tube (pyosalpinx),

g-Gangrenous inflammation

• extensive tissue necrosis due to anaerobic bacteria
• Examples:

• gangrenous cholecystitis or gangrenous appendicitis
• gas gangrene from wound infection 

III-Chronic inflammation  

• If one or more steps of acute inflammation fail, the inflammatory process persists, involves other participants and results in what is called “chronic inflammation”
• Chronic inflammation (CI) corresponds to inflammation that has no tendency to spontaneous healing and which evolves by persisting or worsening over several months or several years.
• Predominance of mononuclear cellular infiltrate and fibrosis

II-1- Granulomatous inflammation 

It is a particular form of chronic inflammation consisting of a predominance of histiocytic cells (macrophages, epithelioid cells, multinucleated giant cells), lymphocytes, organized into clusters or nodules called GRANULOMA.

• This inflammation can be specific or non-specific 

Non-specific inflammatory fleshy bud

“Specific ” inflammation is inflammation whose morphological characteristics are sufficiently suggestive to allow one to strongly suspect or affirm what the agent is.

• causal trigger of this inflammation or to direct towards a group of etiologies.
• For example, a tuberculoid granuloma with caseous necrosis is synonymous with tuberculosis.

FORMS OF INFLAMMATION

Non-specific granulomatous IC:

• Inflammatory fleshy bud granuloma: 

• Macroscopy: it is well individualized in ulcerated inflammations
• Microscopy: newly formed connective tissue, consisting of:

• Granulation tissue cells
• Fibroblasts and myofibroblasts 
• New fan-shaped vessels
• Ex: gastroduodenal ulcers 

Specific granulomatous IC :

• Different etiological forms of granulomatous inflammation (1) 

 Tuberculous granuloma 

• Of infectious origin
• Of immune origin
• Of unknown origin

Foreign body granuloma

• Of infectious origin
• Tuberculosis

Tuberculosis is a contagious disease between humans caused by Mycobacterium tuberculosis (Koch’s bacillus). 

These mycobacteria are histologically demonstrable with typical bacteriological properties: acid-alcohol resistant, stainable by Ziehl and NELSEEN staining.

Macroscopic appearance of tuberculous lesions 

• Nodular lesions:

• miliary granulations: (up to 1mm), gray or yellowish
•  tubers: can reach up to 10 mm in diameter 
• tuberculoma several centimeters in diameter

• Infiltration-type lesions: extensive, not systematized
• Lesions secondary to softening of the caseum: skin and mucous membrane ulcers (intestine, larynx), fistulas

• The cavern a follicular inflammation: secondary to the death of the tubercle bacilli
• associating epithelioid cells, Langhans cells, and a crown of lymphocytes        epithelioid giant cell granuloma caseofollicular inflammation
• Caseification is a homogenization necrosis.
• Macroscopically ; the caseum is pasty white, unctuous. Reminiscent of curdled milk
• Microscopically ; Caseum is an eosinophilic, cracked, acellular substance
• Caseofollicular granuloma is a specific lesion of tuberculosis
•  Caseum can liquefy and be eliminated after fistulization into a cavity or duct,

• Leprosy
• Leprosy in its tuberculoid form is characterized by epithelioid granulomas of the dermis and nerves

• Tuberculous form of Syphilis   characterized by tuberculous granuloma and gummatous necrosis associated with obliterating arterioles lesions 
• Champions:

Aspergillosis

Candidiasis

• Parasites

Echinoccosis 

Bilharsiosis 

• Virus 

Nicolas FABRE’s illness

• – Immune-related injury 
• Rheumatoid nodule: Seen in rheumatoid arthritis, often in the synovial membranes, includes a central fibrinoid focus surrounded by a crown of histiocytes in a palisade arrangement
• Wegener’s granuloma fibrinoid necrosis surrounded by fibroblast arranged in a palisade
• Horton’s temporal arteritis
• Lesion of unknown etiology
• Sarcoidosis
• It is a disease of unknown cause, anergizing, considered to result from an excessive cellular immune response to one or more antigens of exogenous or endogenous origin.
•  It can affect all the viscera with a predominance in the respiratory tree (figure 3.60).
• Histologically, it produces a follicular inflammation, without ever necrosis, associating epithelioid cells, Langhans-type giant cells (frequently containing in their cytoplasm inclusions called asteroid bodies and Schaumann bodies) and lymphocytes
• Crohn’s disease 
• Chronic inflammatory disease of the digestive tract, of unknown cause, with the presence of small epithelioid granulomas in the mucosa of the digestive tract.
• secondary injuries to heavy metals
•  berylium and zirconium 
• Foreign body granuloma: 

• Foreign body giant cells: large cells with multiple randomly arranged nuclei that surround and engulf exogenous or endogenous material
• III.2. Non-granulomatous IC:
• IC with mononuclear infiltrate, necrosis and fibrosis: chronic hepatitis
• IC with macrophages and intra cytoplasmic microorganisms: lepromatous leprosy 
• IC rich in eosinophils: parasitoses 

IV-Comparative table between acute and chronic inflammation

FORMS OF INFLAMMATION

V- Conclusion 

• Determining the different anatomo-clinical forms of inflammation represents a very important step that can guide therapeutic  management .
•  The treatment will be adapted to each form, the aim of which is to avoid the occurrence of complications and after-effects. 

FORMS OF INFLAMMATION

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FORMS OF INFLAMMATION