Dermatology Flashcards
Describe the progression from melanocytic naevi (mole) to nodular melanoma
Melanocytic naevi -> dysplastic melanocytic naevi -> in situ melanoma -> superficial spreading melanoma -> nodular melanoma
What is the main cause of all skin cancer?
Sun exposure - UV light
What is the treatment for malignant melanoma?
Surgical excision.
Give 5 causes of generalised pruritus but no rash
- AGEING.
- Chronic renal failure.
- Cholestasis e.g. PBC.
- Iron deficiency.
- Lymphoma.
- Polycythaemia.
- Hypothyroid.
- Drugs
Give 3 causes of generalised pruritus with rash
- Urticaria.
- Atopic eczema.
- Psoriasis.
- Scabies.
- Lichen planus
What investigations might you do in someone with pruritus?
- FBC.
- Ferritin levels.
- U+E.
- LFT’s.
- TFT’s
What cytokines are commonly targeted in the treatment of pruritus?
IL-4 and IL-13.
Why do transdermal drugs need to be lipophilic?
They need to be lipophilic in order to get through the lipid rich stratum corneum
Give 2 essential properties of transdermal drugs.
- Lipophilic.
2. High affinity for their targets.
Give 3 advantages of transdermal drug delivery.
- Avoids first pass effect, hardly metabolised.
- No pain.
- Controlled dosing
What are emollients used for?
They hydrate the skin and reduce itching
In what diseases would the use of emollients be indicated?
Dry skin, eczema
What receptors do glucocorticoids target?
Cytoplasmic receptors.
How does hydrocortisone work?
Hydrocortisone targets cytoplasmic receptors. It leads to a reduction in pro-inflammatory cytokines and an increase in anti-inflammatories.
In what diseases would the use of hydrocortisone be indicated?
Eczema, contact dermatitis
Give 3 potential side effects of glucocorticoids.
- Skin thinning.
- Oral candidiasis.
- Acne.
- Striae.
- Bruising.
What receptors do vitamin A analogues target?
Nuclear retinoic acid receptors.
Name a vitamin D analogue
Calcipotriol
How does calcipotriol work in the treatment of psoriasis?
Calcipotriol is a vitamin D analogue. It has anti-proliferative and anti-inflammatory effects.
In what diseases would the use of calcipotriol be indicated?
Psoriasis.
What receptors does tazarotene bind to?
Tazarotene is a Vitamin A analogue. It binds to nuclear retinoic acid receptors.
How does tazarotene work in the treatment of acne and psoriasis?
Tazarotene is a Vitamin A analogue. It binds to nuclear retinoic acid receptors and modifies gene expression and inhibits cell proliferation.
In what diseases would the use of tazarotene be indicated?
Psoriasis, acne
Would you prescribe tazarotene to a pregnant lady?
NO! Tazarotene is highly teratogenic.
What class of drug is tacrolimus?
Calcineurin inhibitor
When might you prescribe someone tacrolimus?
Tacrolimus is often used as a second line treatment for eczema.
(1st line = glucocorticoids e.g. hydrocortisone).
Name 3 drug induced dermatological reactions.
- Exanthematous reactions.
- Urticaria.
- Stephen Johnson syndrome.
Give 5 signs of eczema.
- Superficial skin redness/inflammation.
- Oozing.
- Scaling.
- Pruritus.
- Flexors typically affected e.g. at elbows.
Describe the aetiology of eczema.
- Genetic predisposition - loss of function mutations in filaggrin.
- Environmental triggers and irritants.
Describe the treatment for eczema.
- Avoid irritants and allergens.
- Use emollients liberally and frequently.
- First line - hydrocortisone.
- Second line - tacrolimus.
- Third line - sedative anti-histamines.
Briefly describe the pathophysiology of acne
Seborrhea (increased sebum production) -> narrowed follicle blocks sebum, comedo formation -> sebum stagnates and p.acne colonises -> inflammation of pilosebaceous unit.
Describe the treatment for acne.
Treatment is important to avoid scarring and psychological distress:
- Regular washing with acne soaps to remove grease.
- Benzoyl peroxide and topical clindamycin.
- 2nd line - topical retinoids e.g. tazarotene.
- 3rd line - low dose oral antibiotics e.g. doxycycline.
- Hormone treatment can also be used
What is psoriasis?
A chronic hypo-proliferative disorder characterised by well demarcated silvery grey, scaly plaques over extensor surfaces such as elbows and knees and in the scalp.
What environmental factors can cause psoriasis in a genetically susceptible individual?
- Group A streptococcal infection.
- Lithium.
- UV light.
- Alcohol.
- Stress.
Describe the treatment for psoriasis.
- Emollients and reassurance.
- Vitamin D and A analogues e.g. calcipotriol and tazarotene.
- Phototherapy.
What is necrotising fasciitis?
Deep spreading infection of all layers of the skin -> necrosis.
Give 3 risk factors for necrotising fasciitis.
- IVDU.
- Diabetes mellitus.
- Homeless.
- Recent surgery.
What bacteria can cause necrotising fasciitis?
- Type 1: aerobic and anaerobic.
2. Type 2: group A strep e.g. s.pyogenes.
What is the treatment for necrotising fasciitis?
- Surgical debridement.
2. Aggressive IV benzylpenicillin and clindamycin.
What is cellulitis?
Inflammation of the SC layer of the skin.
What bacteria is the commonest causal organism of cellulitis?
S. pyogenes.
Give 5 signs of cellulitis.
- Inflammation.
- Swelling.
- Redness.
- Warmth.
- Pain.
- Unilateral.
What is the differential diagnosis in someone with the signs and symptoms of cellulitis?
DVT
What is the treatment for cellulitis?
Penicillin and flucloxacillin.
