Urticaria / Allergic Rash

Question 1

Definition

Answer 1

Aka hives, wheals is a superficial swelling of the skin resulting in itchy raised red rash

Question 2

Difference between angio-oedema and urticaria

Answer 2

Urticaria - caused by mast cell activation in the epidermis and mucous membranes

Angio-oedema - caused by mast cell activation in the deep dermis

Question 3

Causes of acute urticaria

Answer 3

Allergens:

foods
insect bites
latex
drugs

Question 4

Pathophysiology

Answer 4

When pt comes into contact with an allergen histamine and other IMs are released from activated mast cells.

These mast cells causes inflammation and tissue remodelling

Question 5

Name the two types of urticaria

Answer 5

Acute - one off episode in response to an allergen. Is self limiting

Chronic - lasts for longer than 6 weeks with no known external cause

Question 6

Presentation of acute - SCAM

Answer 6

S - anywhere
C - erythematous
A - intense pruritus, angioedema
M - well defined wheals varying in size and shape.

Question 7

Explain the Urticaria Activity Score

Answer 7

Person records severity of itching and the number of wheals daily for 7 days

Must have a score of 7 or above to indicate disease is not controlled

Question 8

Investigations

Answer 8

FBC - eosinophils may be raised

LFTs - may be viral hep

TFTs - thyroid autoantibodies are associated with chronic urticaria

H.Pylori testing - slightly associated with CU

Allergy testing

Skin biopsy

Question 9

Differentials

Answer 9

Atopic eczema

Contact dermatitis

Chronic pruitus

Insect bite

Question 10

Management

Answer 10

1. Removal of triggers
2. Non-sedating antihistamines (ceterizine, H2 recep antagonists
3. Leukotrine receptor antagonists or biologics
4. prednisalone

Symptomatic management includes calamine lotion, education and regular follow ups