Emergency dermatology Flashcards
(42 cards)
List some causes of urticaria, angioedema and anaphylaxis
Idiopathic Food Drugs Insect bites Contact - latex Viral infection Parasitic infection Autoimmune Hereditary
Describe the pathophysiology of urticaria
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
How does urticaria present
Swelling involving the superficial dermis, raising the epidermis - itchy wheals
How does angioedema present?
Deeper swelling involving the dermis and subcutaneous tissue - swelling of the tongue and lips
How does anaphylaxis present?
Bronchospasm
Facial and laryngeal oedema
Hypotension
Can initially present with urticaria and angioedema
What is the management of urticaria?
Antihistamines
What is the management of angioedema?
Corticosteroids
What is the management of anaphylaxis?
Adrenaline
Corticosteroids
Antihistamines
What is a complication of angioedema and anaphylaxis
Asphyxiation and death
What is erythema nodosum
A hypersensitivity response to a variety of stimuli
What causes erythema nodosum
Group A beta haemolytic streptococcus Primary tuberculosis Pregnancy Malignancy IBD Chlamydia Leprosy
How does erythema nodosum present
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
Describe erythema multiforme
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
Describe Steven Johnson syndrome
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
Describe toxic epidermal necrosis
Usually drug induced
Acute severe disease characterised by extensive skin and mucosal necrosis accompanied by systemic toxicity
Describe the management of TEN and SJS
Early recognition and call for help
Full supportive care to maintain haemodynamic equilibrium
What is the mortality rate for SJS
12%
What is the mortality rare for TEN
> 30%
What is death from SJS and TEN usually due to?
Sepsis, electrolyte abnormalities or multiorgan failure
Describe acute meningococcaemia
A serious communicable infection transmitted via respiratory secretions, bacteria get into the circulating blood
What organisms cause acute meningococcaemia
Gram negative diplococcus Neisseria meningitides
Describe the presentation of acute meningococcaemia
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
What is the treatment of acute meningococcaemia
Antibiotics (eg. benzylpenicillin) Prophylactic antibiotics (eg. rifampicin) for close contacts (ideally within 14 days of exposure)
What are the complications of acute meningococcaemia
DIC
Septic shock
Multiorgan failure
Death
