Chronic Inflammation

Question 1

How is chronic inflammation distinguished from acute inflammation?

Answer 1

• infiltration with mononuclear cells (macrophage, lymphocytes & plasma cells)
• tissue destruction
• repair (angiogenesis & fibrosis)

Question 2

Causes of chronic inflammation

Answer 2

• persistent infections
• prolong exposure to potentially toxic agents
• immune mediated inflammatory diseases (autoimmune disease)

Question 3

Cells involved in chronic inflammation?

Answer 3

• macrophages (dominant)
• lymphocytes
• plasma cells
• eosinophils
• mast cells

Question 4

Why macrophage is important in chronic inflammation?

Answer 4

• macrophages have a large supply of products it can produce when activated
• the products of activated macrophages serve to
  1. Eliminate injurious agents
  2. Initiate repair process
  3. Responsible for much of the tissue injury in chronic inflammation
  How?
  - some of the products are
  - toxic to microbes and host cells
  - cause influx of other cell types
  - cause fibroblast proliferation, collagen deposition & angiogenesis

Question 5

Morphologic features of chronic inflammation

Answer 5

• infiltration by mononuclear cells
• tissue destruction
• attempts at healing (fibrosis & angiogenesis)

Question 6

Two types of chronic inflammation

Answer 6

• non-specific (due to viral infection, other bacterial infections, autoimmune & toxin)
• granulomatous (epithelioid appearance)

Question 7

Chronic peptic ulcer disease is an example of non-specific chronic inflammation. What are the causes and what are the characteristics macroscopically & microscopically?

Answer 7

• due to H. Pylori infection or NSAID ingestion
• macroscopic :
  
  • round to oval shape
  • sharply punched out defect
  • clean edges
• microscopic :
  
  • ulcer edge : denuded mucosa lining
  • ulcer floor : acute & chronic inflam cells accumulate
  • ulcer base : inflam granulation tissue, vascular prolif and fibroblasts
  • fibrous scar in the healed area

Question 8

What is granuloma?

Answer 8

consists of aggregation of macrophages that transformed into epithelioid (epithelium-like cells) surrounded by mononuclear leukocytes (lymphocytes/plasma cells)

Question 9

What are the two types of granulomas?

Answer 9

1. Foreign body granulomas
   - caused by foreign bodies (assoc. w/ intravenous drug abuse)
   - large
   - non caseating granulomas (consist of histiocytes)
   - do not cause specific inflam or immune response
2. Immune granulomas
   - caused by insoluble particles typically microbes
   - capable of inducing a cell-mediated immune response
   - produce granulomas when the inciting agent is poorly degradable

Question 10

Describe caseous granuloma contents from center to outer layer

Answer 10

Center : caseous necrosis center

Inner layer : epithelioid cells,
multinucleated cells may or may not be present

Middle layer : lymphocytes are found

Outer layer : predominantly fibroblasts

Question 11

Outcomes of chronic inflammation

Answer 11

• healed by fibrosis (scar)

If persistent chronic inflammation

• sinus with formation of pus
• contraction of scar / stricture
• obstruction
• development of malignant tissue (such as in ulcerative colitis)