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3. DERMATOLOGY > Emergency > Flashcards

Flashcards in Emergency Deck (12)
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What can cause urticaria / angiodema / anaphylaxis?

Food (nuts, sesame seeds, shellfish, dairy)
Drugs (penicillin, contrast media, NSAIDs, morphine, ACEI)
Insect bites
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?

Include Tx

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%


How is erythema multiforme treated?

Treat infection
Stop medication causing reaction
Systemic corticosteroids to reduce inflammation

Typically self resolves over weeks

If recurrent due to herpes simplex, continuous aciclovir can be preventative.