Dermatology - Acute Dermatology Flashcards
What is urticaria?
Oedema of the dermis, raising the epidermis.
Secondary to increased permeability of capillaries, secondary to histamine release from mast cells.
What is angioedema?
Deeper swelling of the dermis and subcutnaeous tissue, often causing swelling of the tongue and lips.
What are the features of anaphylaxis?
- bronchospasm
- angioedema
- hypotension
- urticaria
Management of urticaria.
Antihistamines
Management of angioedema.
Corticosteroids
Management of anaphylaxis.
500mcg 1:1000 IM adrenaline (adults).
300mcg 1:1000 IM adrenaline (children).
150mcg 1:1000 IM adrenaline (infants).
Complications of
a) urticaria
b) angioedema
c) anaphylaxis
a) uncomplicated when alone
b) asphyxia, cardiac arrest and death
b) asphyxia, cardiac arrest and death
What is erythema nodosum?
Discrete tender nodules on the shins that indicate hypersensitivity.
Causes of erythema nodosum.
- group A streptococcus
- primary TB
- pregnancy
- malignancy
- sarcoidosis
- IBD
- chlamydia
- leprosy
What is erythema multiforme?
An acute self-limiting inflammatory condition, with herpes simplex virus being the main precipitating factor.
What is Stevens-Johnson syndrome?
A rare and unpredictable reaction to a medication, causing skin and mucosal loss.
What drug class is most commonly associated with Steven-Johnson syndrome?
Antibiotics
Features of Steven-Johnson syndrome.
Features usually begin within a week of starting abx:
- prodromal symptoms
- tender / painful rash
- mucosal involvement
Mucosal sites affected in Steven-Johnson syndrome.
At least 2 mucosal sites:
- eyes
- lips / mouth
- pharynx / oesophagus
- genital area
- trachea / bronchi
- GI tract (diarrhoea)
Complications of Steven-Johnson syndrome.
- dehydration
- infection
- ARDS
- GI ulceration / perforation
- sepsis
- DIC
- VTE
- toxic epidermal necrosis (TEN)
How is SJS diagnosed?
- skin detachment <10% BSA
- widespread erythematous / purpuric macules / atypical targets
How is TEN diagnosed?
- skin detachment >30% BSA
- widespread purpuric macules / atypical targets
How is mortality in SJS and TEN predicted?
SCORTEN - illness severity score.
+1 point for each criteria present at time of admission:
1) Age > 40 years
2) Presence of malignancy (cancer)
3) Heart rate > 120
4) Initial percentage of epidermal detachment > 10%
5) Serum urea level > 10 mmol/L
6) Serum glucose level > 14 mmol/L
7) Serum bicarbonate level < 20 mmol/L.
SCORTEN 0-1 > 3.2%
SCORTEN 2 > 12.1%
SCORTEN 3 > 35.3%
SCORTEN 4 > 58.3%
SCORTEN 5 or more > 90%
Management of SJS / TEN.
- stop causative drugs
- hospital admission
- fluidised air bed
- sepsis 6
- pain relief
How long does the acute phase of SJS last?
10 days
Long term consequences of SJS / TEN.
- pigment change
- skin scarring
- loss of nails
- scarred genitalia
- blindness
- lung disease (e.g. bronchiolitis, bronchiectasis, obstruction)
What is erythroderma?
An exfoliative dermatitis involving at least 90% of the skin surface.
Causes of erythroderma.
- eczema
- psoriasis
- lymphoma
- drugs
Presentation of erythroderma.
- inflammed, oedematous and scaly skin
- lymphadenopathy
- malaise
- systemically unwell
Treatment of erythroderma.
- treat underlying cause
- emollients and wet-wraps (skin hydration)
- topical steroids
Complications of erythroderma.
- secondary infection
- dehydration
- electrolyte imbalance
- hypothermia
- high-output cardiac failure
- capillary leak syndrome
Prognosis of erythroderma.
Mortality ~30%
What is eczema herpeticum?
A serious complication of atopic eczema, where co-infection with herpes simplex virus results in widespread eruption.
Management of eczema herpeticum.
- admission to hospital
- antivirals (e.g. aciclovir)
- antibiotics (ie. secondary bacterial infection)
Complications of eczema herpeticum.
- herpes hepatitis
- encephalitis
- DIC
- death (rare)
What is necrotising fasciitis?
A rapidly spreading infection of the deep fascia, with secondary tissue necrosis.
Causes of necrotising fasciitis.
- Group A haemolytic streptococcus
- anaerobic / aerobic bacteria
Presentation of necrotising fasciitis.
- severe pain
- erythematous, blistering necrotic skin
- systemically unwell
- surgical emphysema
Management of necrotising fasciitis.
Urgent surgical referral for extensive surgical debridement.
IV antibiotics.
Prognosis of necrotising fasciitis.
Mortality up to 76%
