Dermatology Flashcards
List the different forms of eczema
1) Atopic dermatitis
2) Contact dermatitis
3) Dyshidrotic dermatitis
4) Nummular dermatitis
5) Neurodermatitis
6) Sebhorreic dermatitis
What is the most common form of eczema?
Atopic dermatitis
What is eczema?
Chronic, relapsing, inflammatory skin condition characterised by an itchy red rash that favours skin creases such as folds of elbows or behind the knees (flexor surfaces)
What are some trigger factors for atopic eczema?
Exogenous: Irritants eg soap Skin infection eg s aureus Contact allergens Extremes of temp and humidity (worse at winter / sweating) Abrasive facbrics eg wool Dietary factors (50% children) Inhaled allergen eg pollen
Endogenous:
Genetic mutations affecting filaggrin
Stress
Hormonal changes in women eg premenstrual flare-ups / deterioration in pregnancy
What is filaggrin?
A protein critical to the conversion of keratinocytes to the proteins/lipid squames (flake of skin) that make up the stratum corneum (outermost layer of skin)
What is the diagnostic criteria for atopic eczema?
Itchy skin plus 3 or more of:
1) Hx of itchiness on flexor surfaces
2) Hx asthma or hay fever (or hx atopic disease in a first degree relative <4yr)
3) Generally dry skin in preceding year
4) Visual flexural eczema
5) Onset in first 2 years of life
= no itching - probs not eczema
Where may atopic eczema present in children 18 months or under?
Cheeks
What is eczema herpeticum?
HSV-1 infection superimposed onto active atopic eczema
DERMATOLOGICAL EMERGENCY
How does eczema herpeticum present?
Areas of rapidly worsening, painful eczema
Clustered blistered with early-stage cold sores
Punched out erosions = circular, depressed, ulcerated lesions) usually 1-3mm that are uniform in appearance. They may coalesce to from larger areas of erosion with crusting
+/- fever, lethargy, distress, LN
What is the treatment of eczema herpeticum?
Immediate acyclovir either PO/IV
Immediate same day referral
What are some complications of eczema herpeticum?
Scarring from blisters
Infection in the cornea (herpetic keratitis) left untreated can lead to blindness
Rarely organ failure and death if virus spreads to brain, lungs and liver
Ddx of atopic eczema
1) Psoriasis - but this is extensor surfaces
2) Contact dermatitis
3) Seborrheic dermatitis
4) Fungal infections
5) Lichen simplex chronicus
6) Scabies
What investigations are done for atopic eczema?
Clinical diagnosis
IgE and specific radioallergosorbant tests (RASTs) only confirm atopic nature of individual
Swabs useful if not responding treatment identify abs-resistant s aureus or additional step infections
What other atopic disease are associated with atopic eczema? (3)
Asthma
Hay fever
Allergic rhinitis
What is the management of atopic eczema?
Avoid triggers
Emollient therapy to keep skin hydrated = at all times
Topical steroids - hydrocortisone 1% initially and increase as required
PO antihistamine may reduce itching
What is the ideal use of an emollient?
Best when skin is moist but useful at all times
Use liberally
Combo of cream, ointment, bath oil and emollient soap = max effect
- Dry areas = oil based
- Wet areas = water based
Freq of every 4 hrs or 3-4 times/day
250g/week prescription for a child
What is the treatment of a bacterial infection in eczema?
14-day course of flucloxicillin for s aureus
Erythromycin if penicillin allergy
What is lichenification?
Thick leathery patchers of skin resulting form repeated scratching
What is the treatment lichenification?
Corticosteroid
Bandages containing ichthammol paste (reduces pruritus) + zinc oxide cn be applied
Coal tar can be useful in some cases
What are the two types of contact dermatitis?
Irritant
Allergic
Where does dyshidrotic dermatitis affect?
Hands and feet
Who does nummular dermatitis affect?
M>F
Men usually first outbreak 50’s
Women get it in adolescence / early adulthood
How does nummular dermatitis present?
Coin shaped red marks
Legs, backs of hangs, forearms, lower back, hips
How does neurodermatitis arise?
Skin irritation develops in spots frequently scratched
Usually skin outbreak doesn’t get any bigger but skin can grow thick and wrinkled
What is sebhorreic dermatitis? Where does it arise?
aka dandruff - causes skin to fall off in flakes
In infants = scalp
Adults also eyebrows / sides of nose / behind ears
Overgrowth of yeast that normally lives in these areas as well as well as overgrowth and rapid shedding of cells on scalp
What is the management of sebhorreic dermatitis?
Shampoo containing salicylic acid, selenium sulfinde, zinc pyrithione, or coal tar
Antifungal treatments can be rubbed into the areas
Steroid lotions
What is stasis dermatitis?
Results from inadequate venous return from lower limb
Over time can cause skin to develop brown stains (hemosiderin)
What is the prognosis of eczema?
Infantile eczema resolves by 2yrs in 50%
Atopic eczema resolves by age 13yr in 60%
Eczema herpeticum usually resolves in 4 weeks
What is impetigo?
Common superficial skin condition divided into non-bullous and bullous forms
Highly infectious
What is the more common type of impetigo?
Non-bullous
What are the most common causative organisms of non-bullous impetigo?
Staph aureus
Strep pyogenes
MRSA rising
What are some RF for impetigo?
Poor hygiene
Skin conditions leading to a break in skin - atopic eczema, bites, trauma to skin, scabies, chicken pox, burns, contact dermatitis
How does non-bullous impetigo present?
Start as tiny pustules / vesicles that evolve into honey-crusted plaques (tend to be <2cm diameter)
Usually around mouth and nose (but can be on extremities eg bites / scabies)
Satellite lesions from auto inoculation
+/- itching
Little / no surrounding erythema or oedema
Regional LN enlarged
How does bullous impetigo present?
Bullous lesions with thin roof that tend to rupture spontaneously
Usually on face, trunk, extremities, buttocks or perineal regions
More likely to occur on top of other disease eg atopic eczema
More common in neonates but can occur in any age
More likely to be painful and be associated with symptoms of malaise
What is ecthyma?
Begins as non-bullous impetigo but ulcerates and becomes necrotic
It is deeper and may occur with lymphadenitis
List some ddx for impetigo
Contact dermatitis Scabies Viral skin infection eg Herpes simplex / herpes zoster Bullous pemphigoid Erysipelas Atopic eczema Burns TJS TEN
What investigations are done for impetigo?
Diagnosis clinical
Swab can be useful if severe / MRSA suspected / recurrent or failing to respond to treatment
How is impetigo managed?
Hygiene advice
Do not attend school until lesions are dry / scabbed over or the affected person has been on abx for 48hrs
1st line - topical fusidic acid
2nd line - topical mupirocin (if MRSA suspected)
3 times a day for 7 days