Dermatology Flashcards
Most common cause of recurrent erythema multiforme?
HSV
When is chickenpox contagious?
2 days prior to rash and until all lesions have crusted over
How long does chickenpox vesicles take to break, and when do crusts fall off?
8-12 hours, 7 days
Post-herpes zoster complications?
Post-herpetic neuralgia, myelitis, encephalitis
Hutchinson’s sign?
Vesicles found on the side/tip of the nose in ophthalmic zoster, marker of serious ocular complications
Lesion of molloscum contagiosium
Pearly papule with central umbilication and a core that can be expressed by applying firm pressure to either side of lesion. Can scar (atrophic )
How do children and adolescents get molloscum?
Children: from family or with people they swim/bathe with. usually armpits and waist
Adolescents: pubic region as STIs
Treating molloscum
- Can leave alone (will resolve within 8 months usually)
2. Cryotherapy, curettage, tape occlusion
How can HPV be transmitted (for warts)
Contact with infected skin/contaminated surfaces, easier if there are breaks in the skin.
How to treat warts?
- Usually resolves within 2 years
2. Can also apply topical salicylic acid or cryotherapy
Cause of HFM?
Coxsackie virus A16
Where does impetigo spread easily?
Warm moist environments with close physical contact and poor hygiene
What is ecthyma?
A deeper ulcerated and scarring infection of the dermis from impetigo
How to control spread of impetigo?
Cover affected areas and keep affected children away from school
Use separate bath towels and launder in hot water daily
Treat crusted areas with moist compresses for 10 minutes 3 times daily, then remove residual crusts
What is cellulitis?
A bacterial infection of the dermis and subcutaneous tissues characterised by pain, redness and oedema
What is erysipelas?
A superficial form of cellulitis, predominantly involving the dermis. Has well-defined edges and may be raised.
Treatment of acne
Education: not due to diet or hygiene, explain actual cause, don’t pick and squeeze, don’t over wash, don’t use too much make up (water based), remove makeup before sleep
Mild acne: benzoyl peroxide + topical retinoid (adapalene 0.1% at night), review in 6 weeks or try topical clindamycin + benzoyl
Moderate: oral antibiotic (MUST be with benzoyl peroxide)
- doxycycline/minocycline/erythromycin
- hormonal: COCP (only improve after 3 months), cytoproterone acetate, spironolactone
Severe: oral isotretinoin (need referral) cause risk of mucosal dryness, bleeding, pancytopenia, depression
Pityriasis rosea features
Herald oval/round patch (1-2 weeks) which is salmon-pink/copper-coloured
Then generalized coin-shaped patches with scaly margins following Christmas tree pattern on back, t-shirt pattern on front
Itchy
Management of pityriasis rosea
Bathe and shower using neutral soap
Soothing bath oil
For itch, apply mild topical CS or calamine lotion with 1% phenol in aqueous cream
Severe itch use potent topical CS
UV therapy - sunlight/UV 3x a week with care
Treatment for psoriasis
Avoid known ppt factors: infection, trauma, emotional stress, beta blockers, lithium, NSAIDS, COCP, sunburn
Healthy lifestyle
Avoid irritants, soap substitute
Moisturizers!
Potent topical steroids
- short term for up to 6 weeks, intermittent use for flares
Topical calcipotriol (Vit D analogue) which takes 6 weeks to take effect or combination product for longer term use
Coal tar 1% emulsion/gel
phototherapy if extensive disease
systemic: oral methotrexate, oral acitrecin, oral cyclosporine
Psoriatic arthritis imp features
DIP arthritis
Dactylitis (sausage digits)
Joint stiffness
Urticaria management
Avoid triggers
Oral antihistamine
Consider H2 antagonist
Systemic corticosteroid (avoid if possible)
Severe urticaria with hypotension and anaphylaxis: IV Adrenaline
Topical soothing prep like phenol in calamine or menthol cream
Bath with bath oil
Rosacea mild management
Mild:
- Metronidazole 0.75% BD
- Azelaic acid 15% gel OD
- 6-12 weeks for max response, if unsuccessful add/replace with oral therapy
Rosacea mod/severe
Doxycycline 50-100mg daily for 8-10 weeks
If inadequate after 4 weeks, minocycline
Erythromycin 250-500mg BD off pregnant woman
Laser therapy/isotretinoin
