Classification of Inflammation

What are the common criteria for classification of inflammation?

Duration

Distribution

Severity

Morphology

Response of the tissue

What are the common classifications of exudate in inflammation?

Serous/Edema

Catarrhal

Fibrinous

Purulent

Hemorrhagic

Eosinophilic

Lymphocytic

Granulomatous

What is serous inflammation?

Accumulation of serum-like fluid

What are the effects of serous inflammation?

Dilution of the offending agent

Excessive fluid can interfere with tissue function

What is the gross appearance of serous inflammation?

Watery fluid within body cavities or tissues

Pre-inflammation edema

What is the histological appearance of serous inflammation?

Homogenous pink fluid

What is catarrhal inflammation?

Presence of large amounts of mucus

What effects does catarrhal inflammation have?

Protection of mucosal surfaces

Dilution of the offending agent

What is the gross appearance of catarrhal inflammation?

Clear, slimy film that covers a mucosal surface

Appears as shreds and clumps when it's partially dehydrated

What is the histological appearance of catarrhal inflammation?

Pale, blue material that covers mucosal epithelium

Mucus producing cells are increased in size and number

What is fibrinous inflammation?

Presence of a large amount of fibrin due to intravascular leakage

What are the effects of fibrinous inflammation?

Protection of underlying tissue

Prevention of blood loss

Scaffold for subsequent formation of fibrous tissue

What is the gross morphology of fibrinous inflammation?

Yellowish adhesive material that can occur as a granular covering over a tissue, to thick sheets, clumps, or fine

What is the histological appearance of fibrinous inflammation?

Fibrillar, web-like eosinophilic material

What is purulent inflammation?

Presence of large number of neutrophils

What are the effects of purulent inflammation?

Defense against infectious agents

Production of pro-inflammatory agents/toxins

Can sometimes interfere with tissue function

What is the gross appearance of purulent inflammation?

Viscous to watery, cream-colored material on mucosal surfaces or within tissues

What is the histological appearance of purulent inflammation?

Large numbers of neutrophils

Often accompanied by fibrin and inflammatory debris

What is an abscess?

Localized and confined accumulation of neutrophils and liquefied debris

What does an abscess represent?

Failure of acute inflammation to remove the inflammatory sequence

What are the characteristics of an abscess?

Chronic lesion

Fibrous capsule that can thicken over time

Walled off from normal adjacent tissue

What is hemorrhagic inflammation?

Presence of large amounts of hemorrhage at an inflammatory site

What is hemorrhagic inflammation associated with?

More severe inflammation

What is the gross morphology of hemorrhagic inflammation?

Inflamed mucosa or tissue is deep red

Associated exudate is red-tinged

What is the histological morphology of hemorrhagic inflammation?

Large numbers of erythrocytes are present in the inflammatory region

What are the causes of eosinophilic inflammation?

Hypersensitivity reactions

Parasitic infections

What is the effect of eosinophilic inflammation?

Mediates local or systemic hypersensitivity reactions

What is the gross morphology of eosinophilic inflammation?

Grey to greenish grey appearance of tissue

What causes lymphocytic inflammation?

Certain viral infections

Chronic bacterial and fungal infections

Immunological reactions

What is lymphocytic inflammation an important component of?

Chronic inflammation

What exudate types are associated with acute inflammation?

Fibrinous and purulent

What exudate types are associated with chronic inflammation?

Lymphocytic and granulomatous

What is the gross morphology of lymphocytic inflammation?

Not often evident grossly

May give affected tissue a whitish-appearance

What causes granulomatous inflammation?

Persistent (chronic) bacterial infections

Most fungi

Certain parasites

Foreign bodies

What is the gross morphology of granulomatous inflammation?

Diffuse thickening of an affected tissue

Formation of firm nodules or masses (granulomas)

What do typical granulomas consist of?

Central core of caseous necrosis

Zone of epithelioid macrophages and giant cells

Zone of lymphocytes

Outer zone of fibroblasts and collagen (fibrous capsule)