Urticaria & Angioedema MCQs

Darier's Sign :The skin characteristically urticates within minutes of gentle rubbing in children causing localized pruritus, redness and wheal, which subside within an hour. It is not 100% specific for mastocytosis, since it has been described on rare occasions in juvenile xanthogranuloma and acute lymphoblastic leukaemia of neonates Reference : Rooks textbook of dermatology, 9 th edition, chapter 46, page 4

Type I hypersensitivity is also known as an immediate reaction and involves immunoglobulin E (IgE) mediated release of antibodies against the soluble antigen. This results in mast cell degranulation and release of histamine and other inflammatory mediators. Manifestations - anaphylaxis, urticaria, angioedema, food, and drug allergies The allergens that result in a type I hypersensitivity - pollen, mites, or foods, drugs, etc Reference: Rooks textbook of dermatology, 9 th edition, chapter 42, page 4

Acute urticaria resolves within 6 weeks . Urticaria longer than 6 weeks' duration is considered chronic. Reference : Rooks textbook of dermatology, 9 th edition, chapter 42, page 5

Acquired angioedema occurs because of an acquired C1 esterase inhibitor deficiency. It is usually characterized by recurrent episodes of asymmetric swelling of the face and oral area, without urticaria or pruritis. The disease is usually self limiting but laryngeal swelling can cause significant morbidity. Patients with this disorder either have a total quantitative deficiency or a qualitative deficiency. Although it is usually a clinical diagnosis, frequently along with a positive family history. Laboratory data to confirm diagnosis include serum C1INH, and C4. Reference : Rooks textbook of dermatology, 9 th edition, chapter 43, page 4

The 3 types of HAE can be differentiated with complement testing and, in the case of HAE with normal C1 inhibitor levels, genetic testing. Type I HAE is characterized by the following: Low C1 esterase inhibitor (C1-INH) protein level Low C4 level Normal C1q level Type II HAE is characterized by the following: Normal or elevated, but dysfunctional, C1-INH level Low C4 level Normal C1q level HAE with normal C1 inhibitor levels is characterized by the following: Normal C1-INH level Normal C1-INH functional assay Normal C4 and C1q level Factor XII mutation may be present Reference : Rooks textbook of dermatology, 9 th edition, chapter 43, page 4

Cutaneous Mastocytosis (CM) Most cases of Pediatric mastocytosis are sporadic and appear during the first 2 years of life, especially on the trunk Urticaria pigmentosa is the most frequent variant Three main forms of CM (defined by the WHO) Urticaria pigmentosa (UP - Maculopapular cutaneous mastocytosis MPCM) Diffuse cutaneous mastocytosis (DCM) Mastocytoma of skin Reference : Rooks textbook of dermatology, 9 th edition, chapter 46, page 4