5
Chronic Urticaria and Angioedema
Î CU is defined as urticaria that has been continuously or
intermittently present for ≥6 weeks. (D) The duration of CU varies
considerably; however, physical urticarias tend to persist the
longest, often for many years. (C)
Î Some patients with CU might have both urticaria and angioedema,
occurring simultaneously or separately. (C)
Î Skin mast cells are the most important cells in patients with
CU, and histamine is the predominant mediator, although other
cells and mediators also play a key role. (LB) Activation of the
coagulation cascade, including increased prothrombin fragment
F1+2 and D-dimer levels, has been described in patients with CU
and might be a marker for CUA severity. (C)
Î Evaluation of a patient with CU should involve consideration of
various possible causes. Most cases do not have an identifiable
cause. (C)
Î Numerous autoimmune disorders, including SLE, dermatomyositis
and polymyositis, Sjögren syndrome, type 1 diabetes, rheumatoid
arthritis, celiac disease, and Still disease, have been associated
with CU. (C)
Î Serology to diagnose underlying autoimmune diseases (e.g.,
connective tissue disease) is NOT warranted in the initial
evaluation of CU in the absence of additional features suggestive
of a concomitant autoimmune disease. (B)
Î Thyroid autoantibodies are frequently identified in patients with
CU. (C)
• The clinical relevance of these tests for patients with CU has not been established.
Î Chronic urticarial vasculitis, associated with low or normal
complement levels, can present as a primary autoimmune
disorder or develop secondary to an autoimmune disorder, such as
SLE. (B)
Î Urticarial vasculitic lesions can sometimes be evanescent, lasting
<24 hours, which is similar to CU. For this reason, urticarial
vasculitis cannot be completely excluded based on the history of
lesions spanning <24 hours. (B)
