Inflammation: Classification

Question 1

What are the criteria for classification of inflammation?

Answer 1

• Duration
• Distribution
• Severity
• Morphology
• Response of the tissue
• All can be included as components of a morphologic diagnosis

Question 2

What are the durations of inflammation?

Answer 2

• Peracute:
  
  • Begins minutes to hours after insult
  • Cna last fo several hours
  • Prominent vascular changes
• Acute:
  
  • Begins 4-6 hours after insult
  • Can last for several days
  • Vascular and erly cellular changes
• Subacute:
  
  • Begins several days after insult
  • Can lst several weeks
  • mixed cellular response with decreasing vascular response
• Chronic:
  
  • Begins several days to weeks after insult
  • Can last for weeks, months or years
  • Mononuclear cells and fibrosis with minimal vascular response

Question 3

How is the distribution of the lesion classified?

Answer 3

• Focal
  
  • ​A single delineated lesion
• Multifocal
  
  • ​multiple, randomly scattered focal lesions
• Locally extensive
  
  • ​a single lesion involving a large area of tissue
• Diffuse
  
  • ​A lesion involving the entire tissue in which it is found

Question 4

How is the severity of the lesion classified?

Answer 4

• Mild
  
  • Vascular change, mild cellular change
  • NO tissue destruction
• Moderate
  
  • ​Prominant vascular and cellular change
  • some tissue destruction
• Severe
  
  • ​Extension of vascular and cellular changes
  • extensive tissue destruction

Question 5

What are the common classification of Exudate / cell type?

Answer 5

• Serous
• Catarrhal
• Fibrinous
• Purulent
• Hemorrhagic
• Eosinophilic
• Lymphocytic
• Granulomatous

Question 6

What is Serous inflammation?

Answer 6

• Accumulation of serum-like fluid
• Causes:
  
  • Joint trauma
  • Early response to bacterial and viral infection
  • Mild Chemical irritants
  • Certain insect bits
• Effects:
  
  • Dilution of the offending agent
  • Excessive fluid can interfere with tissue function

Question 7

What is the morphology of serous inflammation?

Answer 7

• Gross appearance:
  
  • Watery fluid within body cavities or tissue
• Histological appearance:
  
  • Homogenous pink fluid

Question 8

What is catarrhal inflammation?

Answer 8

• Presence of large amounts of mucus
• Causes:
  
  • Mild upper Respiratory viral infections
  • Mild irritants
• Effects:
  
  • Potection of mucosal surfaces
  • Dilution of the offending agent

Question 9

What is the morpholgy of cararrhal inflammation?

Answer 9

• Gross:
  
  • Clear, slimy fim that covers mucosal surface
  • Can appear as shreds and clumps when it is partially dehydrated
• Histological:
  
  • Pale, blue material that covers mucosal epithelium
  • Mucus producing cells are increased in size and #

Question 10

What is fibrinous inflammation?

Answer 10

• Presence of a large amount of fibrin
• Causes:
  
  • Bacterial infections
  • Certain viral infections
  • Burns
• Effects:
  
  • Protection of underlying tissue
  • Prevention of blood loss
  • A scaffold for subsequent formation of fibrous tissue

Question 11

What is the morphology of fibrinous inflammation

Answer 11

• Gross:
  
  • Yellowish adhesive material
  • can occur as a granular covering, to thick sheets, clumps or fine
• Histological:
• Fibrillar, web-like eosinophilic material

Question 12

What is purulent inflammation?

Answer 12

• Presence of large number of neutrophils
• Causes:
  
  • Certain types of bacteria
  • Certain chemical irritants
• Effects:
  
  • Defense against infectious agents
  • Production of pro-inflammatory agents/toxins
  • Sometimes, interference with tissue function

Question 13

What is the morphology of purulent inflammation?

Answer 13

• Gross:
  
  • Viscous to watery, cream-colored material on mucosal surfaces or within tissues
• Histological:
  
  • Large numbers of neutrophils are present, often accompanied by fibrin and inflammatory debris

Question 14

What is an abscess?

Answer 14

• A localized and confined accumulation of neutrophils and liquefied debris
  
  • Represents failure of acute inflammaitno to remove the inflammatory stimulus
  • A chronic lesion
    
    • can take several weeks to form
  • Has a fibrous capsule
    
    • thin, can thicken overtime
  • Walled off from normal adjacent tissue
    
    • can act as a space occupying mass and interfere with tissue/organ function

Question 15

What is hemorrhagic inflammation?

Answer 15

• Presence of large amounts of hemorrhage at an inflammatory site
• Causes:
  
  • Agents that cause vascular inury
    
    • highly virulent infectious agents
    • Certain chemicals
• Effects:
  
  • Typically arise quickly
  • Often associated with more severe inflammation

Question 16

What is the morphology of hemorrhagic inflammation?

Answer 16

• Gross:
  
  • Inflamed mucosa or tissue is deep red
  • associated exudate is red-tinged
• Histological:
  
  • large numbers of erythrocytes are present in the inflammatory region

Question 17

What is eosinophilic inflammation?

Answer 17

• Presence of large numbers of eosinophils
• Causes:
  
  • Hypersensitivity reactions
  • Parasitic infections
• Effects:
  
  • Mediates local or sytemic hypersensitivity reactions

Question 18

What is the morphology of eosinophilic inflammation?

Answer 18

• Gross:
  
  • Affected tissue may have a grey to greenish-grey appearance
• Histological:
  
  • Affected tissue contains large numbers of eosinophils

Question 19

What is lyphocytic inflammation?

Answer 19

• Presence of large numbers of lyphocytes
• Causes:
  
  • Certain viral infections
  • Chronic bacterial and fungal infections
  • Immunological reactions
• Effects:
  
  • Immunlogial response to antigens
  • Important component of chronic inflammation

Question 20

What is the morphology of lymphocytic inflammation?

Answer 20

• Gross:
  
  • Not often evident grossly
  • May give affected tissue a whitish-appearance
• Histological:
  
  • Numerous lymphocytes are present either individually or in nodular aggregates

Question 21

What is granulomatous inflammation?

Answer 21

• Presence of large numbers of macrophages
• Causes:
  
  • Persistent (chronic) bacterial infections
  • Most fungi
  • Certain parasites
  • Foreign bodies
• Effects:
  
  • Associated with chronic, difficult to manage inflammatory agents
  • Can form solid masses and interfere with tissue function

Question 22

What is the morphology of granulomatous inflammation?

Answer 22

• Gross:
  
  • Can occur as diffuse thickening of an affected tissue
  • Or the formtion of firm nodules or masses
• Histological:
  
  • Numerous macrophages are present along with cells derivved from macrophages, and lymphocytes and plasma cells

Question 23

What is the morphology of a granuloma?

Answer 23

• Consist of:
  
  • Central core of caseous necrosis
  • Zone of epithelioid macrophages and giant cells
  • Zone of lymphocytes
  • Outer zone of fibroblasts and collagen
• Many variations depending on the age of the granuloma and the inciting stimulus
  
  • some lack central necrotc core
  • some have minimal fibrosis

Question 24

What are the classifications of tissue response?

Answer 24

• Alterative changes:
  
  • Necrotizing
  • Ulcerative
  • Atrophic
  • Fibrosing
• Prolifrative changes:
  
  • Hyperplastic
  • Hypertrophic