Derm Flashcards
What is urticaria?
Small, itchy lumps that appear on the skin which may be associated with patchy, erythematous skin.
Acute or chronic
Common causes of acute urticaria
Triggered by anything that causes mast cells to release histamine
Allergies to food, medication or animals
Chemicals, latex, stinging nettles
Medications
Viral infections
Insect bites
Causes of chronic urticaria
Autoimmune disorder where antibodies target mast cells to release histamine
Chronic inducible is recurrent urticaria which is caused by certain triggers such as sunlight, temperature change, exercise, strong emotions, hot or cold weather
Chronic idiopathic has no clear cause
Autoimmune urticaria is associated with an underlying autoimmune condition such as SLE
How is urticaria managed?
Antihistamines: fexofenadine for chronic, oral steroids for short severe flare
If very problematic and severe then consider anti-leukotrienes, omalizumab or cyclosporin
What is eczema?
chronic atopic condition caused by defects in the normal continuity of the skin barrier, leading to inflammation
Where does eczema usually occur?
flexor surfaces (inside of elbows and knees)
How should eczema be managed?
- maintenance and management of flares
- maintenance = emollients used often, avoid soaps and body washes
- manage flares = topical steroids
What are some complications of eczema?
- bacterial infection caused by infective organism, usually staphylococcus aureus
- eczema herpeticum caused by HSV or varicella zoster
What is psoriasis?
- chronic autoimmune condition that causes recurrent symptoms of psoriatic skin lesions
- usually dry, flaky, scaly, erythematous skin lesions on knees, elbow or scalp
What are the different types of psoriasis?
- Plaque = thickened erythematous plaques with silver scales
- Guttate = children, small raised papules across trunk and limbs, usually triggered by streptococcal throat infection, stress or medications
- Pustular = pustules form under areas of erythematous skin
- Erythrodermic = erythematous inflamed areas covering most of the surface of the skins
How does psoriasis present in children?
- guttate in children, often triggered by a throat infection
Signs of psoriasis
- Auspitz = small points of bleeding when plaques are scraped off
- Koebner phenomenon = development of psoriatic lesions of skin affected by trauma
- Residual pigmentation = after lesion resolves
How should psoriasis be managed?
- topical steroids
- topical vitamin D analogues
- topical dithranol
- topical tacrolimus
- phototherapy with ultraviolet B light
What are the associations of psoriasis?
- Nail psoriasis = pitting, thickening, discolouration, ridging, onycholysis
- Psoriatic arthritis
- Psychological implications
What is cellulitis? What usually causes it?
bacterial infection of the deep dermis and subcutaneous tissue, usually lower limb
- Streptococcus pyogenes and staphylococcus aureus but also Streptococcus pneumoniae, Haemophilus influenzae
How does cellulitis present?
acute onset of red, painful, hot, swollen skin
- possibly orange-peel appearance, blistering, bleeding and lymphangitis
Risk factors for cellulitis
- skin trauma
- ulceration
- obesity
- diabetes
- venous insufficiency
- eczema
- oedema and lymphoedema
How should cellulitis be investigated?
FBC, ESR and CRP, U&Es
- swab, biopsy
How should cellulitis be managed?
- antibiotics
- analgesia, fluid intakes, elevate leg for comfort and to relieve any oedema
- manage underlying risk factors
Where can pressure sores occur?
usually over a bony prominence but can form on any part of the body
Key diagnostic factors for pressure sores
- risk factors
- non-pressure relieving support surface
- localised skin changes on area subject to pressure
- shallow open wound or tissue loss on areas subjected to pressure
Risk factors for pressure sores
- immobility
- sensory impairment
- older age
- surgery
Features of arterial ulcers
- occur distally (toes or dorsum of foot)
- associated with peripheral arterial disease with absent pulses, pallor and intermittent claudication
- smaller than venous ulcers
- deeper than venous ulcers
- well-defined borders
- punched-out appearance
- pale colour
- less likely to bleed
- painful
- worse at night and on elevation
How should we manage arterial ulcers?
- same as peripheral arterial disease
- urgent referral to vascular to consider revascularisation
- debridement and compression are not used
