What is the answer...All of the following are causes of an urticarial rash with hives EXCEPT: A Hypersensitivity reaction to an allergen B Lymphoma C Parasitic infection D Serum sickness E Systemic lupus erythematosus
The correct answer is **B) Lymphoma**.
Lymphoma is not a common cause of an urticarial rash with hives. Urticaria, characterized by itchy hives, is typically associated with hypersensitivity reactions, serum sickness, systemic lupus erythematosus, and parasitic infections. These conditions can trigger immune responses that release histamines, leading to hives. While lymphoma may cause various skin manifestations, it is not commonly associated with urticaria.
Systemic lupus erythematosus (SLE) can cause urticaria due to the autoimmune nature of the disease, where the body's immune system mistakenly attacks its own tissues, including skin. In SLE, immune complexes (antibody-antigen complexes) can form in the blood and deposit in small blood vessels of the skin, causing inflammation and leading to a type of urticaria known as urticarial vasculitis.
Key mechanisms by which SLE can cause urticaria include:
Immune Complex-Mediated Vasculitis: In SLE, immune complexes can activate the complement system, resulting in inflammation of small blood vessels. This vascular inflammation can present as raised, red, and itchy lesions that resemble hives but often last longer than typical urticaria and may be painful.
Histamine Release: In some cases, the immune dysregulation in SLE triggers the release of histamine from mast cells, similar to an allergic reaction, leading to the classic itchy and swollen appearance of hives.
Autoantibodies: SLE can produce autoantibodies that target skin components, which may contribute to skin manifestations like urticaria.
Unlike typical urticaria, urticarial vasculitis in SLE is more persistent, may be painful rather than itchy, and often leaves a bruise or residual pigmentation after the lesions fade.