Sean Klepper M.D.
Artur Zembowicz M.D....
- Defined as urticaria that persist for longer than 6 weeks
- Most common in middle-aged individuals
- Caused in some cases by IgG autoantibodies which cross-link IgE receptors on basophils and mast cells, causing their degranulation
- Some cases are associated with allergies, especially to foods or aspirin.
- Other cases are secondary to cholinergic urticaria, caused by an increase in body temperature following exercise, overheating or stress.
Histologic Features (similar to what is seen in acute urticaria):
- Dermal edema
- Vascular dilatation and endothelial swelling
- Scant perivascular infiltrate of lymphocytes, eosinophils and neutrophils
- Interstitial neutrophils and mast cells