Dermatology Flashcards
TEN/SJS/Erythema Multiforme
SJS/TENS: Severe skin detachment (epidermis from dermis at epideraml-dermis junction) and mucocutaneous complications (involves both mucous memebranes and skin). Immune reaction to foreign antigens.
Sx: maculopapular rash, bullae
SJS: involves <10% total surface body area
TEN: involves >30% total surface body area
Erythema multiforme:
Causes: HSV
Target lesions
SJS:
Causes: M.pneumonia, viral, drugs: anti-epileptics
SJS/TENS
10-30% TSBA
TENS:
>30% TSBA
Causes: drugs e.g. antibiotics (quinolones), anti-epileptics (carbamazepine, phenytion), analgesia (paracetamaol), corticosteroids
BCC
Commonest skin Ca.
Rare mets
Locally invasive
Cause: UV radiation, PTCH (patched) tumour suppressor gene, inherited gene defects (Ghorlin syndrome: multiple BCCs)
Nodular: pearl, shiny, telangictasia
Morpheic: white, waxy. Present late as hard to see
Superficial
Pigmented
Tx: surgical excision + reconstruction - BCC <20mm = 4-5mm margin Morpheic: 13-15mm margin High risk: morpheic, less well defined margins - Mohs surgery
Curettage and cautery
Cryotherapy
Imiquimod cream (immune response modifier)
Radiotherapy
Melanoma
Malignant tumour from melanocytes
Causes: UV radiation, genetics e.g CDKN2A, hx of sunburn, fair skin type
Types:
Superficial spreading - brownish plaque. Torso on men, legs on women.
Nodular - dark, raised, thick
Lentigo - subtle, brown, often on face, elderly
Acral melanoma - non-hair bearing skin e.g. hand/feet
Subungal melanoma - nails
Melanoma insitu
A- asymmetry B- border irregularity C - colour variation D - diameter >6mm E - evolving
Prognostic features:
LN mets
Breslow thickness - thickness of tumour from surface to deepest point of invasion
Ulceration
Tx: Thin: <1mm: Excise 1cm margin Intermediate: 1-4mm: Excise 1-2cm margin Thick >4mm: Excise 2cm margin
Metastatic:
Nodal basin resection
Radiotherapy - doesn’t improve survival
Chemo - immunotherapy (monoclonal antibody) - Ipililumab (activates CTLA4)
Targeted therapy - BRAF gene inhibitors
Sentinel LN biopsy:
Dye (radioactive/coloured) injected around tumour, first drained LN (sentinel node) is excised
Squamous cell carcinoma
2nd most common skin Ca.
From keratinocytes
Raised, keratotic
Commonly sun exposed areas
Potential to metastasise:
Risk increases: non-sun exposed site, diameter >4mm
Acitinic keratoeses: pre-malignant SCC
Bowen’s disease: SCC in situ
Cause: UV radiation Marjolin's ulcer (old wounds) Inherited syndromes e.g. albinism Immunosuppression - HIV, organ transplant Precursor lesions: actinic keratoses
Tx:
<2cm: 4mm margin
Mohs surgery >2cm : 6mm margin (tissue examined under microscopic whilst being removed)
Burns
Electrical: can cause cardiac arrhythmias. Underlying tissue damage. Rhabdomyolysis.
High voltage: cardiac monitoring, assess area. IV fluids, monitor UEs, UO. Fasciotomies.
Fluid replacement: Large burns cause large fluid loss Parklands formula: fluid req (ml)= TBSA (total body SA) = weigh (kg) x 3 1/2 over first 8 hrs 1/2 over next 16 hrs
Severity depends on TSBA and depth of burn
Types of burns:
1st degree burns:
Erythema: Does not extend through epidermis. Dry, painful. E.g. Sunburn.
2nd degree:
Superficial partial thickness: epidermis removed, dermis intact. . Heal <14d.
Deep partial thickness; extends into reticular dermis. Blood supply damaged. Heal with hypertrophic scarring.
Wet, painful, e.g. scalding
3rd degree:
Full thickness: Extends through skin into subcutaneous tissue
No blistering, hard, woody. No sensation. E.g. flame injury
4th degree burns:
Involves subcutaneous tissue, tendon/bone
E.g. High voltage electricity
Surgical tx:
Dressings
Skin flaps
Layers of skin
Come Lets Get Sun Burnt
Epidermis:
Stratum Corneum - dead skin cells
Stratum Lucidum - only palms, soles of feet
Stratum Granulosum - keratin production
Stratum Spinosum - strength
Stratum Basale - keratinocytes
Dermis - blood vessels, nerves, hair follicle
- Papillary layer (superficial)
- Reticular layer
Subcutaenous tissue/Subcutis - fat (maintain temp), blood vessels, nerves
Acute uticaria
Commonest skin presentation in A&E
Wheals, itchy, resolves <24 hrs
Immune mediated: Type I HS IgE
Non immune mediated: mast cell deregulation - opiates
Causes: viral, parasitic infections, physical stimulants e.g. cold
Tx: antihistamines, steroids
Erythroderma
Inflammatory skin condition affecting entire skin surface, >90% erythema
Causes: psoriasis, eczema, drug reactions
Sx: erythema, oedema, hair loss, keratoderma of palms and soles
Complications:
Secondary infection, loss of temp control, fluid/electrolyte imbalance
Ix: skin swabs (infection), skin biopsy
Tx: stop unnecessary medication
Apply emollients, mild topical steroids, wet dressings, manage fluid/electrolytes
Rosacea
Characterised by redness and flushing, primarily affecting central face
Also includes telangiectasia, roughened skin, rhinophyma
Rosacea fulminans - characterised by dramatic eruption of inflamed papules and yellow pustules
Triggers: climatic exposure - sunlight, drugs - amiodarone, corticosteroids
Sx: erythema, flushing, telangiectasia, scleritis, papules, pustules
Ix: clinical diagnosis, skin biopsy
Tx:
topical abx: topical metronidazole
benzoyl peroxide
laser therapy +/- tacrolimus (telangiectasias, erythema)
Skin blisters
Fluid filled bumps under skin
Causes: Impetigo: bullous and non-bullous form Staphylococcal scalded syndrome HSV - blisters which burst forming ulcers, VZV Autoimmune: Bullous pemphigus - subepidermal blisters Autoantibodies against desmosomes Blisters rupture easily Chest, back Mucosal erosions early sign
Bullous pemphigoid - itching, redness, blisters
Autoantibodies against hemi-desomosomes
Subepidermal so doesn’t rupture easily
Flexors
Dermatitis herpetiformis
Very Itchy, vesicles assoc, with coeliac
Tx: steroids
