1. Chronic inflammation is defined as prolonged inflammation where tissue destruction and inflammation occur simultaneously over a long period. 2. It can occur through three pathways: following acute inflammation, recurrent acute attacks, or starting gradually without an initial acute phase. 3. Chronic inflammation is characterized by mononuclear infiltration, ongoing tissue damage or necrosis, and proliferative changes in tissues.

1. CHRONIC INFLAMMATION

2. DEFINITION
• Chronic inflammation is defined as prolonged
process in which tissue destruction and
inflammation occur at the same time.
INFLAMMATION
TISSUE DESTRUCTION
CHRONIC INFLAMMATION

3. CAUSES:
• May occur by one of the following 3 ways:
1. Chronic inflammation following acute
inflammation.
2. Recurrent attacks of acute inflammation.
3. Chronic inflammation starting de novo.

4. 1. Chronic inflammation following Acute Inflammation.
Extensive Tissue Destruction Bacterial survival
Acute Inflammation
UNRESOLVED
CHRONIC INFLAMMATION

5. Eg: Osteomyelitis
• Acute Osteomyelitis ---- > Chronic Osteomyelitis

6. 2. Recurrent attacks of Acute Inflammation:
Repeated bouts/Attacks of Acute Inflammation
Chronicity of the process
CHRONIC INFLAMMATION

7. E.g: Recurrent Urinary Tract Infection leading to
Chronic Pyelonephritis
Recurrent Urinary Tract Infection/Pyelonephritis Chronic Pyelonephritis

8. 3. Chronic inflammation starting de novo.
ORGANISMS OF LOW PATHOGENICITY
Eg: Mycobacterium tuberculosis
CHRONIC INFLAMMATION STARTING DE NOVO

9. GENERAL FEATURES OF CHRONIC INFLAMMATION
• Following general features characterise any chronic
inflammation:
CHRONIC
INFLAMMATION
1.MONONUCLEAR
INFILTRATION.
2.TISSUE
DESTRUCTION
OR
NECROSIS
3. PROLIFERATIVE
CHANGES

10. TYPES OF CHRONIC INFLAMMATION:
Chronic inflammation is subdivided into 2 types:
1. Chronic Non-Specific Inflammation
2. Chronic Granulomatous Inflammation

11. 1. Chronic Non-Specific Inflammation
• When the irritant substance produces a non-
specific chronic inflammatory reaction with
formation of granulation tissue and healing by
fibrosis, it is called chronic non-specific
inflammation.
E.g. Chronic Osteomyelitis, Chronic Ulcer,
Lung Abscess

12. 2. Chronic Granulomatous Inflammation
• In this, the injurious agent causes a
characteristic histologic tissue response by
formation of granulomas e.g. tuberculosis,
leprosy, syphilis, actinomycosis, sarcoidosis
etc.

13. GRANULOMATOUS INFLAMMATION
Definition:
• Granuloma is defined as a circumscribed, tiny
lesion, about 1 mm in diameter, composed
predominantly of collection of modified
macrophages called epithelioid cells, and
rimmed at the periphery by lymphoid cells.

15. PATHOGENESIS OF GRANULOMA:
Persistence of the poorly digestible antigen e.g.
Mycobacterium tuberculosis, M. leprae.
TYPE IV GRANULOMATOUS HYPERSENSITIVITY REACTION
Formation of Granuloma

16. Sequence in evolution of Granuloma:
Antigen engulfment by Macrophages
Since antigen is poorly degradable
Macrophages present antigen to CD4+T lymphocytes
Activated lymphocytes release lymphokines.
IL-1, IL-2, Interferon-γ TNF-α
PROLIFERATION OF
MORE T CELLS ACTIVATES MACROPHAGES FIBROBLAST PROLIFERATION
ACTIVATED MACROPHAGES TRANSFORM TO
EPITHELIOID CELLS, -> MULTINUCLEATED GAINT CELLS

17. • Thus, a granuloma is formed having:
Macrophages modified as epithelioid cells
in the centre.
With some interspersed multinucleate giant
cells.
Surrounded peripherally by lymphocytes
(mainly T cells).
Healing by fibroblasts or collagen
depending upon the age of granuloma.

18. ANTIGEN ENTRY INTO TISSUE

19. ANTIGEN ENGULFMENT BY MACROPHAGES

20. MACROPHAGES PRESENT ANTIGEN TO CD4+T LYMPHOCYTES

21. LYMPHOKINES
ACTIVATED LYMPHOCYTES RELEASE LYMPHOKINES

22. PROLIFERATION OF MORE T CELLS
BY IL-1, IL-2
INTERFERON-γ
INCREASE MACROPHAGES

23. ACTIVATED MACROPHAGES TRANSFORM TO
EPITHELIOID CELLS

24. EPITHELIOID CELLS FUSE TO FORM
MULTINUCLEATED GAINT CELLS

25. HEALING BY FIRBOBLASTS