41: Urticaria Flashcards
What is urticaria?
Urticaria is defined as a skin disorder characterized by local transient skin or mucosal edema (wheal) and an area of redness (erythema) accompanied by itchy sensations that diminish within 1 day.
What role do mast cells play in urticaria?
Mast cells and their histamine play a crucial role in the pathogenicity of urticaria, as they can release histamine which contributes to the symptoms of the condition.
What are the clinical features of wheals in urticaria?
Wheals are circumscribed, raised, usually pruritic, and evanescent areas of edema that involve the superficial portion of the dermis, and they are highly pruritic.
What is angioedema and how does it differ from urticaria?
Angioedema is a local and transient skin or mucosal edema that develops in deep tissues, mostly without itching but may accompany pain or burning sensations, whereas urticaria involves wheals that are more superficial and itchy.
What are the common triggers that may aggravate urticaria or angioedema?
Common triggers include infections, stress, fatigue, and drugs, especially NSAIDs and ACE inhibitors.
What is the peak age for chronic spontaneous urticaria (CSU)?
The peak age for chronic spontaneous urticaria (CSU) is between 20 to 40 years old.
What are the noncutaneous findings associated with urticaria?
Noncutaneous findings include discomfort of the stomach and intestine, pharyngeal edema (bradykinin-induced), and anaphylaxis, which is a serious, life-threatening generalized or systemic hypersensitivity reaction.
What are the key clinical features that differentiate wheals from angioedema in urticaria?
How does chronic spontaneous urticaria (CSU) with concomitant angioedema differ from CSU without angioedema?
Chronic spontaneous urticaria (CSU) can be categorized based on the presence of angioedema:
- With concomitant angioedema: 33% to 67% of CSU patients experience this, indicating a significant overlap that may complicate management due to the potential for deeper tissue involvement.
- Without angioedema: 29% to 65% of patients, which suggests that a substantial number of CSU cases may not present with this complication, potentially leading to a different therapeutic approach.
What are the potential triggers for urticaria and angioedema?
Potential triggers include infections, stress, fatigue, medications (especially NSAIDs and ACE inhibitors), and autoantibodies against IgE or its receptor.
What are the complications associated with urticaria?
Higher incidence of autoimmune thyroid disease, rheumatoid arthritis, Sjogren syndrome, celiac disease, type I diabetes mellitus, and systemic lupus erythematosus.
How is urticaria classified?
Urticaria is classified by duration, trigger, mode of induction, and underlying causes. Specific subtypes include cholinergic, adrenergic, and aquagenic urticaria.
What is the mechanism of Type I hypersensitivity in urticaria?
In Type I hypersensitivity, mast cells are activated via high affinity IgE receptors and antigen-specific IgE, leading to urticaria symptoms that develop within 15 minutes to 1 hour.
What is the autoimmune mechanism associated with chronic spontaneous urticaria (CSU)?
1/3 to ½ of patients with CSU possess functional IgG antibodies against IgE or high affinity IgE receptors, leading to histamine release.
What is pseudoallergy in the context of urticaria?
Pseudoallergy refers to nonallergic hypersensitivity to dietary pseudoallergens, including naturally occurring food ingredients and additives.
What are the findings related to the coagulation system in patients with urticaria?
Levels of plasma coagulation markers, such as prothrombin fragment 1+2 and D dimer, are higher in patients with urticaria compared to healthy controls.
A patient with urticaria has elevated levels of prothrombin fragment 1+2 and fibrin degradation products. What does this suggest?
Elevated levels of these markers suggest increased potential for blood coagulation, which correlates with disease severity in chronic spontaneous urticaria.
A patient with urticaria has a history of Sjogren syndrome. What is the relationship between these conditions?
Chronic urticaria may be associated with autoimmune disorders like Sjogren syndrome, although the prevalence is low.
A patient with urticaria reports symptoms triggered by food additives. What diagnostic approach can confirm pseudoallergy?
A 3-week pseudoallergen-free diet can help diagnose food pseudoallergy.
What is the role of mast cells in the pathogenesis of urticaria?
Mast cells play a crucial role by degranulating and releasing histamine and other vasoactive mediators.
How do infections contribute to the development of chronic spontaneous urticaria (CSU)?
Acute infections caused by viruses and bacteria are associated with spontaneous urticaria, and chronic infection by Helicobacter pylori is recognized as an important cause of CSU.
What factors may induce or aggravate urticarial reactions?
Factors include aspirin and other NSAIDs, serum sickness, blood products, contrast media, and other mast cell and basophil activators.
What are the risk factors associated with chronic spontaneous urticaria (CSU)?
Risk factors include age, gender ratio of 2:1 (F:M), association with infections and autoimmune disorders, and strong association with HLA-DR4.
A patient develops urticaria after taking NSAIDs. What alternative medication can be considered safer?
COX-2 selective NSAIDs tend to be safer for patients who develop urticaria after taking NSAIDs.