Chronic inflammation combines inflammatory cell infiltration, tissue destruction, and attempts at repair.
Characteristic morphology
•
Acute inflammation shows vascular changes, edema, and predominantly neutrophilic infiltration.
•
Chronic inflammation shows mononuclear cell infiltration, including macrophages, lymphocytes, and plasma cells.
•
Tissue destruction results from the persistent offending agent or the inflammatory cells.
Repair and cellular activity
•
Damaged tissue is replaced with connective tissue through angiogenesis, meaning proliferation of small blood vessels, and fibrosis, culminating in scar formation.
•
The combination of leukocyte infiltration, tissue damage, and fibrosis results from local activation of several cell types and mediator production.
•
Macrophages dominate most chronic inflammatory reactions and destroy foreign invaders and tissues.
Outcomes of acute inflammation
•
Acute inflammation may resolve, progress to chronic inflammation, or heal by fibrosis.
•
Healing by fibrosis is most often the outcome of chronic inflammation.