emergency dermatology Flashcards by Tara Emami

what are the causes of urticria, angioedema, anaphylaxis?

1) idiopathic
2) food eg nuts
3) drugs eg penicillin
4) insect bites
5) contact eg latex
6) viral or parasitic info
7) autoimmune
8) hereditary in some cases of angioedema

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describe the pathophysiology of urticaria

local increase in permeability of capillaries and small venules

histamine from skin mast cells major mediator. loca mediator release from mast cells can be induced by imm+ non-immunological mechanisms

other inflammatory mediators involved eg prostaglandins, leukotrienes, chemotactic factors

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how does urticaria present

swelling involving superficial dermis, raising the epidermis

itchy wheals

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how does angioedema present

deeper swelling involving dermis + subcutaneous tissues

swelling of tongue + lips

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how does anaphylaxis present

bronchospasm, facial + laryngeal oedema, hypotension

can present initally with urticaria + angioedema

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what is the management of urticaria

antihistamines

corticosteroids if severe acute

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what is the management of angioedema

adrenaline
corticosteroids
antihistamines

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what are the complications of angioedema and anaphylaxis

can lead to asphyxia
cardiac arrest
death

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what is erythema nodosum

a hypersensitivity resopnse to a variety of stimuli

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what are the causes of erythema nodosum

group a beta-haemolytic streptococcus
primary tuberculosis
pregnancy
malignancy
sarcoidosis
IBD
chlamydia
leprosy

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how does erythema nodosum present?

discrete tender nodules that can become confluent
leisons continue to appear for 1-2 weeks, leave bruise-like discolouration as they resolve
common site- shins
lesions do not ulcerate, they resolve without atrophy or scarring

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what is erythema multiforme

acute self-limiting inflammatory condition

muscoal involvement absent or limited to one mucosal surface

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what is stevens-johnson syndrome

mucocutaneous necrosis with at least 2 mucosal sites involved. skin involvement limited or extensive.

features may overlap with toxic epidermal necrolysis including a prodromal illness

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what are the causes of erythema multiforme

often unknown
main preciptating factor is HSV
other infections and drugs

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what are the causes of stevens-johnson syndrome

drugs or combinations of infections/drugs

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what can be seen on histopathology with stevens-johnson syndrome

epithelial necrosis with few inflammatory cells

the esxtensive necrosis distinguishes from erythema multiforme

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what is toxic epidermal necrosis TEN

an acute severe disease characterised by extneisve skin + mucosal necrosis accompanied by systemic toxicity

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what is the cause of toxic epidemal necrosis

usually drug-induced

what is seen on histopathology with TEN

full thickness epidermal necrosis with subepidermal detachment

what is the management of erythema multiforme, SJS, TEN?

early recognition
call for help
full supportive care to maintain haemodynamic equilibrium

what are the complications of SJS and TEN?

mortality rate 5-12% SJS
>30% with TEN
death often due to sepsis, electrlyte imbalance or multi-system organ failure

what is acute meningococcaemia?

a serious communicable infection transmitted via respiratory secretions

bacteria gets into circulating blood

what is the cause of acute meningococcaemia?

gram negative diplococcus neisseria meningitides

how does acute meningococcaemia present?

1) features of meningitis- headache, fever, neck stiff
2) features of septicaemia- hypotension, fever, myalgia
3) rash- non-blanching purpuric rash on trunk+ extremities

describe the changing features of a rash in acute meningococcaemia

1) can start with a blanching maculopapular rash 2) then non-blanching purpuric rash 3) rapidly progresses to ecchymoses, haemorrhagic bullae + tissue necrosis

what is the management of acute meningococcaemia?

1) antibiotics eg benzylpenicillin | 2) prophylactic abc eg rifampicin for close contacts within 14days exposure

what are the complications of acute meningococcaemia?

septicaemic shock DIC multi-organ failure death

what is erythroderma

exfoliative dermatitis involving at least 90% of skin surface (red skin)

what are the causes of erythroderma?

1) previous skin disease eg eczema, psoriasis 2) lymphoma 3) drugs eg sulphonamides, gold, sulphonylureas, pencillin, allpurinol, captopril 4) idiopathic

how does erythroderma present?

1) skin appears inflamed, oedematous, scaly | 2) systemically unwell with lymphadenopathy + malaise

how do you manage erythroderma?

1) treat underlying cause if known 2) emollients + wet wraps to maintain skin moisture 3) topical steroids to relieve inflammation

what are the complications of erythroderma?

1) secondary infection 2) fluid loss + electrolyte imbalance 3) hypothermia 4) high-output HF 5) capillary-leak syndrome

what is the prognosis of erythroderma?

depends on underlyign cause | overall mortality rate 20-40%

what is ezcema herpeticum/kaposi's varicelliform eruption?

widespread eruption- serious complication of atopic eczema and other skin conditions

what is the cause of eczema herpeticum

herpes simplex virus

how does eczema herpeticum present?

1) extensive crusted papule, blisters, erosions | 2) systemically unwell with fever + malaise

how do you manage eczema herpeticum?

1) antivirals eg acyclovir | 2) abx for bacterial secondary infection

what are the complications of eczema herpeticum?

herpes hepatitis encephalitis DIC rarely death

what is necrotising fasciitis?

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

what are the causes of necrotising fasciitis?

1) group A haemolytic streptococcus | 2) mixture of anaerobic + aerobic bacteria

what are the risk factors of necrotising fasciitis?

abdominal surgery co-morbidities eg diabetes, malignancy 50% cases occur in healthy

how does necrotising fasciitis present?

1) severe pain 2) erythematous, blistering, necrotic skin 3) systemically unwell with fever + tachycardia 4) crepitus- subcutaneous emphysema 5) X-ray can show soft-tissue gas

how do you manage necrotising fasciitis?

urgent referral for extensive surgical debridement | IV abx

what is the prognosis of necrotising fasciitis?

mortality up to 76%