Emergency dermatology

Question 1

List some causes of urticaria, angioedema and anaphylaxis

Answer 1

Idiopathic
Food
Drugs
Insect bites
Contact - latex
Viral infection
Parasitic infection
Autoimmune 
Hereditary

Question 2

Describe the pathophysiology of urticaria

Answer 2

Due to a local increase in permeability of capillaries and small venules. Large number of inflammatory mediators (prostaglandins, leukotrienes and chemotactic factors) play a role but histamine derived from skin mast cells appears to be major mediator
Local mediator release from mast cells can be induced by immunological and non-immunological mechanisms

Question 3

How does urticaria present

Answer 3

Swelling involving the superficial dermis, raising the epidermis - itchy wheals

Question 4

How does angioedema present?

Answer 4

Deeper swelling involving the dermis and subcutaneous tissue - swelling of the tongue and lips

Question 5

How does anaphylaxis present?

Answer 5

Bronchospasm
Facial and laryngeal oedema
Hypotension
Can initially present with urticaria and angioedema

Question 6

What is the management of urticaria?

Answer 6

Antihistamines

Question 7

What is the management of angioedema?

Answer 7

Corticosteroids

Question 8

What is the management of anaphylaxis?

Answer 8

Adrenaline
Corticosteroids
Antihistamines

Question 9

What is a complication of angioedema and anaphylaxis

Answer 9

Asphyxiation and death

Question 10

What is erythema nodosum

Answer 10

A hypersensitivity response to a variety of stimuli

Question 11

What causes erythema nodosum

Answer 11

Group A beta haemolytic streptococcus 
Primary tuberculosis
Pregnancy 
Malignancy
IBD
Chlamydia
Leprosy

Question 12

How does erythema nodosum present

Answer 12

Discrete tender nodules which may become confluent
Usually appear on the shins
As they resolve they become bruise like in colouration
Lesions continue to appear for 1-2 weeks
Lesions do not ulcerate and resolve without atrophy or scarring

Question 13

Describe erythema multiforme

Answer 13

Often of unknown cause - herpes simplex virus may precipitate it
Self limiting acute inflammatory condition
Mucosal involvement is absent/limited to one mucosal surface only

Question 14

Describe Steven Johnson syndrome

Answer 14

Characterised by mucocutaneous necrosis with at least 2 mucosal sites involved
Skin involvement may be limited or extensive
Drugs or combinations of infections or drugs may be associated
Epithelial necrosis with few inflammatory cells seen on histopathology.
May have a prodromal illness

Question 15

Describe toxic epidermal necrosis

Answer 15

Usually drug induced

Acute severe disease characterised by extensive skin and mucosal necrosis accompanied by systemic toxicity

Question 16

Describe the management of TEN and SJS

Answer 16

Early recognition and call for help

Full supportive care to maintain haemodynamic equilibrium

Question 17

What is the mortality rate for SJS

Answer 17

12%

Question 18

What is the mortality rare for TEN

Answer 18

> 30%

Question 19

What is death from SJS and TEN usually due to?

Answer 19

Sepsis, electrolyte abnormalities or multiorgan failure

Question 20

Describe acute meningococcaemia

Answer 20

A serious communicable infection transmitted via respiratory secretions, bacteria get into the circulating blood

Question 21

What organisms cause acute meningococcaemia

Answer 21

Gram negative diplococcus Neisseria meningitides

Question 22

Describe the presentation of acute meningococcaemia

Answer 22

Features of meningitis - headache, fever, neck stiffness
Features of septicaemia - Hypotension, fever, myalgia
Typical rash - non blanching purpuric rash on trunk and extremities which may be preceded by a maculopapular rash and can rapidly progress into ecchymoses, haemorrhagic bullae and tissue necrosis

Question 23

What is the treatment of acute meningococcaemia

Answer 23

Antibiotics (eg. benzylpenicillin)
Prophylactic antibiotics (eg. rifampicin) for close contacts (ideally within 14 days of exposure)

Question 24

What are the complications of acute meningococcaemia

Answer 24

DIC
Septic shock
Multiorgan failure
Death

Question 25

What is erythroderma

Answer 25

Exfoliative dermatitis involving at least 90% of the skin surface

Question 26

List some causes of erythroderma

Answer 26

Previous skin disease - eczema and psoriasis
Lymphoma
Drugs - sulphonamides, gold, sulphonlyureas, penicillin, allopurinol, captopril
Idiopathic

Question 27

How does erythroderma present?

Answer 27

Skin appears inflamed, oedematous and scaly

Systemically unwell with malaise and lymphadenopathy

Question 28

How is erythroderma treated?

Answer 28

Treat the underlying cause
Emollients and wet wraps
Topical steroids to reduce inflammation

Question 29

What are the complications of erythroderma

Answer 29

Secondary infection 
Fluid loss
Electrolyte imbalance
Hypothermia
High output cardiac failure 
Capillary leak syndrome

Question 30

Describe the prognosis for erythroderma

Answer 30

Depends on underlying diagnosis - 20-40%

Question 31

Describe eczema herpeticum

Answer 31

Widespread eruption - serious complication of eczema

Question 32

What causes eczema herpeticum

Answer 32

Herpes simplex virus

Question 33

Describe the presentation of eczema herpeticum

Answer 33

Extensive crusted papules, blisters and erosions

Systemically unwell with fever and malaise

Question 34

Describe the management of eczema herpeticum

Answer 34

Antivirals

Antibiotics for any secondary bacterial infection

Question 35

List the complications of eczema herpeticum

Answer 35

Herpes hepatitis
Encephalitis
DIC
Rarely death

Question 36

Describe necrotising fasciitis

Answer 36

A rapidly spreading infection of the deep fascia with secondary tissue necrosis

Question 37

What causes necrotising fasciitis

Answer 37

Group A haemolytic streptococci

Mixture of anaerobic and aerobic bacteria

Question 38

What are the risk factors for necrotising fasciitis

Answer 38

Abdominal surgery
Medical comorbidity - diabetes and malignancy
Although 50% occur in healthy individuals

Question 39

Describe the presentation of necrotising fasciitis

Answer 39

Severe pain
Erythematous, blistering and necrotic skin
Systemically unwell with fever and tachycardia
Presence of crepitus - subcutaneous emphysema

Question 40

What may an x-ray show in necrotising fasciitis

Answer 40

Soft tissue gas

Question 41

How is necrotising fasciitis managed

Answer 41

Urgent referral for surgical debridement

IV antibiotics

Question 42

What is the prognosis of necrotising fasciitis

Answer 42

Mortality up to 76%