1.2 Urtica

Wheal, hive.

Wheal: localized transient flattened sub-epidermal edema with initial complete later peripheral erythema; can be red or pale pink
Angioedema: localized edema in the deeper dermis, less sharply defined, firm but compressible swelling

Urticaria: usually associated with marked pruritus (itching)
Angioedema: feeling of pressure, if on mucous membranes sensation of stricture

Urticaria: can appear anywhere on body, especially on trunk and extremities, less often on face and scalp
Deep seated wheals are localized in the  subcutaneous fat
Angioedema: most common on cheeks, eyelids, lips, oral and genital mucosa

Transient, lesions change over minutes to hours, finally annular figurated flattening
Associated with macules, erythema and flushing
Resolves completely without scarring or other changes

An individual hive typically never lasts more than 24 hours, although a case of hives may last days to weeks. Other diseases may cause persistent urticated lesions (vasculitis, lupus erythematosus)
Usually intense pruritus.
Many causes: physical factors, infections, allergic reactions, medications, mastocytosis
Angioedema: deep edema after the lower dermis (pale, firm swelling)

Acute, spontaneous urticaria, chronic urticaria, urticarial exanthema of other reasons. Angioedema.

Mast cells, basophils; release histamine and other inflammatory mediators (prostaglandins, leukotrienes)
Triple response to histamine: pruritus, macular erythema, hive