Recurrent<unk>  at least twice per week for 6 weeks 
Often autoimmune etiology
Physical 
Contact
Dermatographism
Cold
Cholinergic (heat, exercise, stress)
Autoimmune
SLE
Juvenile rheumatoid arthritis
Graves disease
Malignant
Contact
Dermatographism
Cold
Cholinergic (heat, exercise, stress)
SLE
Juvenile rheumatoid arthritis
Graves disease
Malignant
Chronic urticaria
Allergic reaction/urticaria
Cold urticaria
Anaphylaxis
Atopic dermatitis
Angioedema
Contact dermatitis
Anxiety attack