Final answer:
Urticarial vasculitis is classified as a type III hypersensitivity reaction, characterized by the formation of immune complexes that result in inflammation of blood vessels. Diagnosis often involves blood tests for C1-INH levels and functional assays, while treatment may include antihistamines and anti-inflammatory drugs.
Step-by-step explanation:
Urticarial vasculitis is classified as a type III hypersensitivity inflammatory reaction. This condition arises due to the formation of immune complexes and their subsequent deposition in the tissues and blood vessels. It involves the production of IgG antibodies that form complexes with soluble antigens, leading to inflammation and damage to blood vessels. These immune complexes can cause blood to leak from damaged vessels, forming purple spots known as petechiae.
Type III hypersensitivities were initially characterized by the work of Nicolas Maurice Arthus and are exemplified by the classic Arthus reaction. To assess these immune reactions, such as in cases of urticarial vasculitis, specific blood tests might be ordered to check levels of C1-INH and the functional assay of C1 inhibitors. In terms of management, a holistic approach is taken, and treatment may include antihistamines, anti-inflammatory drugs, and analgesics.
Clinical manifestations of urticarial vasculitis can include a rash that resembles hives but is caused by inflammation of the blood vessels, rather than a simple allergic reaction. This can lead to longer-lasting spots on the skin and additional systemic symptoms.