Dermatology Flashcards
What are the functions of the skin?
protect against environmental antigens temperature regulation sense vitamin D synthesis prevent fluid loss
What are the 3 layers of the skin?
Epidermis, dermis, SC tissue
What are emollients used for? give 2 examples
to rehydrate the skin and re-establish lipid layer.
Double base and Diprobase
Name the topical corticosteroid ladder?
Hydrocortisone –> eumovate –> Betnovate –> dermovate
3 examples where a topical corticosteroid might be used?
anti-inflammatory, anti-proliferative, autoimmune conditions, allergic conditions
When might oral retanoids be used?
acne, psoriasis
Side effects of oral retanoids?
dry skin/lips, disordered LFTs, increased cholsterol, myalgia, tetarogenic
How does tacrolimus act?
immunosuppressant. Calcineurin inhibitor.
What conditions is atopic eczema associated with?
atopic dermatitis, rhinitis, allergic asthma
What is atopic eczema? What is the distribution?
chronic relapsing inflammatory condition characterized by itchy erythematous scaly patches.
Adults - flexor surface
Infants - face and extensors
What is the pathophys of eczema?
- defective skin barrier function - increases exposure and sensitisation to antigens.
- Immune dysfunction - increased Th2 mediated response which increases IgE response
- Exacerbating factors - infection/soap/dust mites
What is the diagnostic criteria for eczema?
UK working party diagnostic criteria
What are some signs of eczema?
location of the lesions, pruritis, dry skin, erythematous patches, vesicles, weeping
signs of chronic eczema?
lichenification, hypopigmentation
Ix for eczema?
clinical history, serum IgE, allergy testing
Mx pathway for eczema?
- BASIC - hydrate skin, emollients, avoid triggers, antihistamines
- topical steroids
- increasing doses of topical steroids
- systemic therapy (ciclosporin)/UV therapy
What is psoriasis?
inflammatory and hyperproliferative disorder of the keratinocytes and inflammatory cell infiltrate
Signs of psoriasis?
erythematous well circumscribed scaly plaques at extensor surfaces and scalp and belly button
nail pitting, beau lines, oncholysis, arthritis
Management pathway for psoriasis?
- GENERAL - educate, avoid drugs/alcohol/stress which precipitate
- MILD - topical corticosteroids + vitamin D analogue (calcipitriol)
- phototherapy, methotrexate, retinoid
- Ciclosporin
What causes acne?
inflammation of the pilosebaceous follicles
How do hormones contribute to acne?
increased androgens increase the sebum produced. This leads to formation of comedomes and an inflammatory reaction.
Conditions associated with acne?
PCOS, cushing, puberty
Complications of unresolved acne?
hyperpigmentation, scarring, deformity, psychological and confidence issues
management pathway of acne?
- topical benzyl peroxide/retinoid
- topical antibiotic added
- Systemic tetracycline
- Oral isoretinoin
Oral contaceptive might be used in girls
Which cells are affected in SCC?
cancer of the keratinocytes
RF for all skin cancer?
sun exposure, chronic inflammation, immunosuppressed, previous cancer
What does SCC look like?
crusty and scaly lesion, ill-defined nodule which can ulcerate and bleed.
What is BCC?
slow growing tumour of the epidermal keratiocytes arising from hair follicle.
How do you go about describing a skin lesion?
A - asymmetry B - border C - colour D - diameter E - evolution
What is malignant melenoma?
invasive malignant tumour of the epidermal melanocytes, with high potential to metastasize
What is the score used to quantify the depth of invasion on histology for skin cancer?
Breslow thickness score.
What does impetigo look like? What causes it?
good crusting and weeping, caused by S.Aureus
Mx of impetigo?
topical fusidic acid, oral fluclox
What is cellulitis? Causes?
spreading bacterial infection of the deep SC tissue causing overlying skin inflammation. Erythematous, oedema, warm and tender.
CAUSE: S.Aureus
DD for cellulitis?
bakers cyst, abscess, DVT, gout, necrotizing fasciitis
Mx for cellulitis?
flucloxacillin
What is scalded skin syndrome caused by?
toxin realised by coag +ve staph, causes blistering and fever
Mx of scalded skin syndrome?
analgesia, fluclox, fluids (VERY PRONE TO DEHYDRATE)
what is scabies?
infection with mites (transmitted skin to skin)
Features of scabies?
pruritis, erythematous papules, linear burrows in interdigital spaces
Ix for scabies?
skin scrapings - can visualised the mites and eggs with a microscope
Mx for scabies
Topical Permethrin + antihistamine (treat whole family)
Causes of a venous ulcer?
chronic venous insufficiency, incompetent valves, varicus veins, oedema
Signs of venous insufficiency
ankle swelling, increased pigment, heavy legs, itching, varicose veins, lipodermatosclerosis
what do venous ulcers look like?
large and shallow with sloping edges. They are not painful and have an irregular border.
Ix of any leg ulcer?
ABPI, pulses, measure the area, swab for microbiology and biopsy
Mx of a venous ulcer?
gradual compression and leg elevation, keep clean.
Causes of an arterial ulcer?
atherosclerosis, tissue hypoxia
Signs of arterial insufficiency?
absent pulses, pale, peripherally cold, parathesia, paralysis
Symptoms of a arterial ulcer?
painful, irregular edge, grey base, no bleeding on debridement, punched out
What must you not do to a arterial ulcer?
COMPRESS
Appearance of a neuropathic ulcer?
punched out, surrounded by inflammation, bleeding with debridement painless, sloughy and necrotic base
How does urticaria present? why?
itchy wheals - increased permeability of capillaries due to histamine released by skin mast cels.
Mx or urticaria?
antihistamines
What is angio-oedema?
swelling of tongue/eyelids/lips - can cause asphyxia, cardiac arrest and death.
What is anaphylaxis?
life threatening bronchospasm, facial and laryngeal oedema and hypotension
Mx of anaphylaxis?
IM adrenaline, airway protection, IV chlorphenamine, IV corticosteroids
What drugs causes SJS?
anticonvulsants, Abx, NSAIDS
What does SJS look like? What sign is positive?
detatchment of epidermis from dermis, mucotaneous necrosis and systemic toxicity. Nivolsky sign positive.
What bacteria causes nectrotizing fasciitis?
group A haemolytic strep
Presentation of NF?
severe pain, erythematous blistering and nectrotic pain, systemically unwell.
Mx of NF?
fluids, Tazocin, surgical debridement
