Cutaneous drug eruptions

Question 1

What mediates Type I hypersensitivity reactions?

Answer 1

IgE

Question 2

What are the 2 most common symptoms of Type I hypersensitivity reactions?

Answer 2

Urticaria

Angioedema

Question 3

What mediates a Type II hypersensitivity reactions?

Answer 3

B-cell mediated cytotoxic reactions

Question 4

Which 2 common skin condition classes are due to Type II hypersensitivity reactions?

Answer 4

Pemphigus

Pemphigoid

Question 5

What mediates a Type III hypersensitivity reaction?

Answer 5

Immune-complexes

Question 6

What are the 2 major symptoms of Type III hypersensitivity reactions?

Answer 6

Purpura

Rash

Question 7

What mediates a Type IV hypersensitivity reaction?

Answer 7

T-cells in a delayed fashion

Question 8

What are the 2 major symptoms of Type IV hypersensitivity reactions?

Answer 8

Erythema

Rash

Question 9

Are immunologically-mediated reactions dependent or non-dependent on the dose?

Answer 9

Non-dependent

Question 10

Are non-immunologically mediated reactions dependent or non-dependent on the dose?

Answer 10

Dose dependent

Question 11

What do you consider in a drug reaction diagnosis?

Answer 11

Symmetrical symptoms

Resolve with withdrawal of the drug

Question 12

What are the drug reaction risk factors?

Answer 12

Young adults (not infant or elderly)
Females more than males
Genetics
Concomitant disease
Immunosupressant

Question 13

Describe the exanthematous morphology of drug reaction

Answer 13

Diffuse symmetrically distributed red macule/patches

Commonly pruritic

Question 14

What is the most common morphology of drug eruption

Answer 14

Exantheamatous, at 90%

Question 15

What is the immune mechanism by exanthematous drug eruptions?

Answer 15

T-cell mediated, Type IV hypersensitivity reaction

Question 16

When do exanthematous drug eruptions occur?

Answer 16

4-21 days after first dosing

Question 17

What features suggest an exanthematous drug reaction is severe?

Answer 17

Mucous membrane involvement
Confluent erythema
Fever
Skin pain
Blisters, purpura, necrosis
Sob & wheeze

Question 18

What is an urticarial drug reaction?

Answer 18

IgE mediated type I hypersensitivity reaction

Angioedema or anaphylaxis

Question 19

Describe pustular/bullous drug eruptions

Answer 19

Acneiform reactions, resemble acne in presentation but not the mechanism

Question 20

What is an acute pustular/bullous drug eruption called?

Answer 20

Acute generalised exanthematous pustulosis

Question 21

What characterises a fixed-drug eruption?

Answer 21

Well demarcated round/ovoid lesions that are erythematous and painful

Question 22

Where do fixed drug eruptions usually occur?

Answer 22

Hands
Genitalia
Lips

Question 23

What happens when a fixed drug eruption resolves?

Answer 23

Persistent pigmentation

Question 24

What symptoms does Stevens-Johnson syndrome present with?

Answer 24

Flu-like symptoms

Painful red/purple rash that progresses to blisters

Question 25

Explain toxic epidermal necrosis

Answer 25

Widespread erythema with necrosis of the epithelial and bullous detachment of the dermis

Question 26

What is acute generalised exanthematous pustulosis?

Answer 26

Sudden widespread pustules all over the body

Question 27

What are the 2 forms of phototoxic drug reactions?

Answer 27

Acute and chronic

Question 28

What are the patterns of skin phototoxicity?

Answer 28

Immediate prickle with delayed erythema
Exaggerated sunburn
Exposed telangiectasia
Delayed 3-5 days erythema and pigmentation
Increased skin fragility

Question 29

How do you manage a drug reaction?

Answer 29

Discontinue the drug (completely, replace it)
Topical corticosteorids
Antihistamines

Allergy alert bracelets