Flashcards in Emergency Deck (12)
What can cause urticaria / angiodema / anaphylaxis?
Food (nuts, sesame seeds, shellfish, dairy)
Drugs (penicillin, contrast media, NSAIDs, morphine, ACEI)
Contact e.g. latex
Viral / parasites
Hereditary in some angiodema cases
What is urticaria, angiodema, anaphylaxis?
Local increase in permeability of capillaries and small venules
Large number of inflammatory mediators (including prostaglandins, leukotrienes, chemotactic factors) play role but histamine from mast cells are major mediator. Local mediator release can be induced by immuniological or non-immunological mechanisms
URTICARIA (swelling involving SUPERFICIAL DERMIS, raising dermis) = itchy wheals. Usually uncomplicated.
ANGIODEMA (deeper swelling involving dermis and subcut tissues) = swelling of tongue and lips
ANAPHYLAXIS = bronchospasm, facial and laryngeal edema, hypotension, can present initially with urticaria and angioedema)
Angiodema and anaphylaxis can cause asphyxia, cardiac arrest and death
Management of urticaria, angiodema, anaphylaxis?
Antihistamines for urticaria
Corticosteroids for severe acute urticaria and angioedema
Adrenaline, corticosteroids and antihistamines for anaphylaxis
What is erythema nodosum?
Hypersensitivity response to variety of stimuli, inflammation of subcutaneous fat
Infectious Causes: Group A strep, primary TB, brucellosis, chalmydia, leprosy.
Other causes: pregnancy, malignancy / lymphoma, sarcoidosis, IBD, Behcet's disease
Drug causes: penicillins, sulphonamides, COCP
Discrete TENDER erythematous NODULES which may become confluent, continue to appear for 1-2 weeks and leave bruise-like discolouration as they resolve. SHINS most common site (also forearms, thighs)
Usually resolves within 6 weeks - lesions do not ulcerate and resolve without atrophy or scarring.
What is erythema multiforme?
Acute self-limiting hypersensitivity inflammatory condition (type IV), cytotoxic T cells attack basal epithelium. Usually infection. Herpes simplex is most common cause, also Orf (sheep, goats), idiopathic, mycoplasma, strep, penicillin, sulphonamides, carbamazapine, pheytoin, allopurinol, NSAIDs, OCP, nevirapine, connective tissue disease e.g. SLE, sarcoidosis, malignancy
Mucosal involvement absent or limited to one mucosal surface.
Target lesions 2mm-2cm - central necrosis with surrounding erythema, initially back of hands/feet - spread to torso. Upper limbs > lower limbs. Pruritis occasionally, usually mild. (can also get macules, vesicles, bullae, papules).
Erythema multiforme minor = only 1 mucosal site (typically oral), limited region of skin
Erythema multiforme major = more severe form / widespread, associated with mucosal involvement (2 - typically oral, ocular, genital), but only rarely life threatening, usually haemorrhagic crusting of vermillion areas of lips.
What is Steven-Johnson syndrome?
Mucocutaneous necrosis with at least 2 mucosal sites involved. Histolopathology: epithelial necrosis with few inflammatory cells. Extensive necrosis distinguishes from erythema multiforme. May have features overlapping with TEN including prodromal illness.
Skin involvement may be limited or extensive. Main associations are drugs or combinations of drugs -
What is toxic epidermal necrosis?
Usually drug induced - acute severe disease characterised by extensive skin and mucosal necrosis, accompanied by systemic toxicity.
Histopathology: full thickness epidermal necrosis with subepidermal detachment.
What is acute meningococcaemia?
Gram negative diplococcus - Neisseria meningitides
Features of meningitis (headache, fever, neck stiffness), septicaemia (hypotension, fever, myalgia) and typical rash.
Non-blanching purpuric rash on trunk and extremities, may be preceded by blanching maculopapular rash, can rapidly progress to ecchymoses, haemorrhagic bullae and tissue necrosis
Management: Abx e.g. benzylpenicillin, prophylactics e.g. rifampicin for close contacts (14 days of exposure)
Complications: septicaemic shock, DIC, multi-organ failure, death
What is erythroderma?
Erythroderma is a term used when more than 95% of the skin is involved in a rash of any kind. Exfoliative dermatitis involving at least 90% skin surface. Skin appears inflammed, oedematous and scaly, systemically unwell with lymphadenopathy and malaise.
Causes: previous eczema, psoriasis, drugs (e.g. gold, sulphonamides, sulphonylureas, pencillin, allopurinol, captopril), lymphomas, leukaemias, idiopathic
Tx: underlying cause where known, emollients + wet wraps maintain skin moisture, topical steroids.
Complications: secondary infection, fluid loss, electrolyte imbalance, hypothermia, high output cardiac failure, capillary leak sydrome (most severe). Prognosis depends on underlying cause, overall mortality 20-40%.
Erythrodermic psoriasis: may result from progression of chronic disease to an exfoliative phase with plaques covering most of the body. Associated with mild systemic upset. More serious form is an acute deterioration. This may be triggered by a variety of factors such as withdrawal of systemic steroids. Patients need to be admitted to hospital for management
What is eczema herpeticum?
Kaposi's varicelliform eruption
Widespread eruption, serious complication of atopic eczema or less commonly other conditions, caused by herpes simplex virus (common in atopic children)
Extensive crusted papules, blisters and erosions
Systemically unwell with fever and malaise
Tx: admit children for IV aciclovir, antibiotics for bacterial secondary infection
Complications: herpes hepatitis, encephalitis, DIC, rarely death
What is necrotising fasciitis?
Rapidly spreading infection of deep fascia with secondary tissue necrosis.
Type 1 = mixed aerobes and anerobes (often post-surgery in diabetics). Type 2 = Strep pyogenes (group A strep).
Risk factors: abdominal surgery, medical conditions e.g. diabetes, malignancy. 50% in previously healthy pts.
Acute onset, severe pain / tender, erythematous, blistering, necrotic skin, systemically unwell with fever and tachycardia, presence of crepitus (subcut emphysema), XR may show soft tissue gas (absence should not exclude diagnosis)
Management: urgent referral for extensive surgical debridement, IV Abx, mortality up to 76%