Dermatology Flashcards
What is eczema?
An itchy, dry inflammatory skin disease
Give examples of endogenous types of eczema.
- Atopic – ‘genetic barrier dysfunction’
- Seborrheoic – face/scalp – scale associated
- Discoid – annular/circular patches
- Pomphylx – vesicles affecting palms/soles
- Varicose – oedema/venous insufficiency
Give examples of exogenous types of eczema.
- Allergic contact dermatitis (sensitised to allergen)
- Irritant contact dermatitis (friction, cold, chemicals e.g. acids, alkalis, detergents, solvents)
- Photosensitive/photoaggravated eczema
What can flares of eczema be associated with?
- Infections/viral illness
- Environment: central heating, cold air
- Pets: if sensitised/allergic
- Teething
- Stress
- Sometimes no cause for flare found
What is the commonest type of eczema?
Atopic
What is atopy?
Overactive immune response to environmental stimulus
How can atopy lead to eczema?
Immune mediated defects in the skin barrier leads to dry inflamed skin
What is the triad of atopy?
- Asthma
- Eczema
- Hayfever
Can have 1, 2 or 3 and usually FMH
How does atopic eczema tend to present in infancy?
Typically starts on the face/neck (cheeks common), can spread more generally
How does atopic eczema present in older children?
- Flexural pattern predominates (antecubital fossae, popliteal fossae, wrists, hands, ankles).
- Facial eczema also possible/can recur.
What causes atopic eczema?
- Inherited abnormalities in the skin leading to barrier defect
- Abnormality in filaggrin expression
What does filaggrin do?
- Filaggrin proteins bind the keratin filaments together.
- Also play a role in producing a natural moisturising factor.
What is the consequence of losing skin barrier function?
Loss of water
- Irritants may penetrate (soap, detergent, solvents, dirt)
- Allergens may penetrate (pollens, dust-mite antigens, microbes)
Who is usually affected by seborrheoic dermatitis?
Often babies under 3 months, usually resolves by 12 months
What is seborrheoic dermatitis associated with in infants?
Cradle cap
Where does seborrheoic dermatitis mainly affect?
Scalp and face
What microorganism is sebeorrhoeic dermatitis associated with?
Associated with proliferation of various species of the skin commensal Malassezia in its yeast form.
How is seborrheoic dermatitis treated?
- Emollients
- Antifungal creams
- Antifungal shampoos
- Mild topical steroids
How does discoid eczema present?
Scattered annular/circular patches itchy eczema
How can discoid eczema occur?
As part of atopic eczema or as a separate entitiy
Where does pomphylx eczema affect?
Hand and foot
How does pomphylx eczema present?
- Characterised by vesicles on the hand and feet
- Intensely itchy
Where does varicose eczema affect?
Affects legs in association with venous insufficicency
What is varicose eczema often associated with?
- Oedema
- Varicose veins
- Chronic leg swelling
How does varicose eczema present?
- Skin dry and inflammed
- Skin may ulcerate
How is varicose eczema treated?
- Emollients
- Topical steroids
- Compression stockings
What causes allergic eczema?
Becoming sensitised to an allergen
What type of testing may be useful in allergic eczema?
Patch testing
What causes irritant eczema?
Repeated contact
- Water and soaps
- Touching irritant foods such as citrus and tomatoes
- Chemical irritants
Should children with eczema have allergy testing?
- Eczema has many causes and allergy is just one
- Majority of children with mild eczema do not need allergy testing
- 80% of childhood eczema is mild
When should food allergy be suspected?
- Immediate reactions (lip swelling, facial redness/itching, anaphylactoid symptoms)
- Late reactions (worsening of eczema 24/48 hours after ingestion) – especially if pattern with specific food (food diaries encouraged).
- GI problems
- Failure to thrive
- Severe unresponsive eczema
- Severe generalised itching
How can food allergy be tested for?
- Blood test for specific IgE antibodies to certain foods
- Skin prick testing
What are the commonest food allergies?
- Milk/dairy
- Soy
- Peanuts
- Eggs
- Wheat
- Fish
What should you beware of in allergy testing?
False positive tests and limitations of allergy testing particularly in atopic eczema
Give examples of airborne allergens.
- House dust mite
- Pet dander
- Pollen
How should food allergies be confirmed?
- Dietary restrictions/eliminations >8 weeks – refer dietitian
- Eliminate one food at a time
- Reintroduce food to confirm allergy
How should eczema be treated?
- Emollients (Lotions, creams or ointments – fragrance free, greasier ointments more effective)
- Topical steroids
- Calcineurin inhibitors (e.g protopic – steroid sparing topical agents)
- UVB light therapy
- Immunosuppressive medication
What is a possible side effect of topical steroids?
Skin thinning with prolonged use
Give examples of different strengths of topical steroids.
- Very potent (Dermovate)600x
- Potent (Betnovate)100x
- Moderate (Eumovate) 25x
- Mild (Hydrocortisone)
How much steroid should be applied?
1 finger tip unit covers the area of a palm
How should steroids be used?
- Once daily for 1-2 weeks
- If improvement then use alternate days for a few more days
- Then if stubborn/persistent areas can use twice weekly in these areas
- If at any point the eczema starts flaring, go back to daily applications
What is impetigo?
A common acute superficial bacteria
How does impetigo present?
Pustules and honey-coloured crust erosions
What is the causative agent of impetigo?
Staph aureus
How is impetigo treated?
- Topical antibacterial (fucidin)
- Oral antibiotic (flucloxacillin)
What is molluscum contagiosum?
Common benign self-limiting infection
What is the causative organism in molluscum contagiosum?
Moluscipox virus
How is molluscum contagiosum transmitted?
Transmission to close direct contacts
How does molluscum contagiosum present?
Pearly papules with umbilicated centres
What is the incubation for molluscum contagiosum?
2 weeks - 6 months
How is molluscum contagiosum managed?
- Can take up to 24 months to clear
- Reassurance
- 5% potassium hydroxide
What are viral warts?
Common non-cancerous growths of the skin caused by infection with HPV
What are warts on the sole of the foot known as?
Verucas
How do viral warts present?
Often skin coloured growths
How are viral warts transmitted?
Direct skin contact
How are viral warts treated?
- Need to stimulate own immune system to respond
- Cryotherapy
- Topical paints (salicylic acid)
- 90% will resolve in 24 months
What is viral exanthems associated with?
Viral illness
- Chicken pox
- Measles
- Rubella
- Roseola (herpes virus 6)
- Erythema infectiosum (parvovirus B19, slapped cheek)
Why does viral exanthems occur?
Either reaction to a toxin produced by the organism, damage to the skin by the organism or an immune response
How does viral exanthems present?
- Fever
- Malaise
- Headache
What is chickenpox?
- Chickenpox is a highly contagious disease caused by primary infection with the varicella-zoster virus.
- One infection is thought to confer lifelong immunity.
Who is susceptible to the varicella zoster virus at all times?
Immunocompromised individuals
How does chickenpox present?
- Red papules (small bumps) progressing to vesicles (blisters) often start on the trunk.
- Itchy. Associated with viral symptoms.
What is the timeline of chickenpox?
- Incubation 10-21 days
- Contagious 1-2 days before rash appears and until lesions have crusted
- Self limiting
What are some rare complications of chickenpox?
- Pneumonia
- Encephalits
How is chickenpox treated?
- Self-limiting
- Infection control (keep of school/nursery)
What are some other names for slapped cheek?
- Fifth disease
- Erythema infectiosum
What causes slapped check?
Parovirus
How does slapped check present?
- Viral symptoms.
- Erythematous rash cheeks initially and then also lace like network rash (trunk and limbs). Can take 6w to full fade.
What does parovirus target?
Red cells in bone marrow
How does slapped check resolve?
Mild self-limiting illness
What is in the incubation period for slapped check?
7-10 days
What are some rare complications of slapped check?
- Aplastic crisis (if haemolytic disorders)
- Risk to pregnant women (spontaneous abortion, intrauterine death, hydrops fetalis)
What causes hand foot and mouth disease?
Enterovirus
- Coxsackie virus A16
- Enterovirus 71
- Other Cxsackie virus
How does hand foot and mouth disease present?
- Blisters on the hands, feet and in the mouth
- Viral symptoms
When do epidemics of hand foot and mouth disease occur?
Late Summer or Autumn months
How is hand foot and mouth disease managed?
- Self-limiting
- Treatment is supportive
How does orofacial granulomatosis present?
- Lip swelling and fissuring
- Oral mucosal lesions: ulcers and tags, cobblestone appearance
What is orofacial granulomatosis associated with?
Crohn’s disease
What are the clinical features of erythema nodosum?
- Painful, erythematous subcutaneous nodules
- Over Shins; sometimes other sites
- Slow resolution - like bruise,6-8 weeks
What are the causes of erythema nodosum?
- Infections: Streptococcus, Upper respiratory tract
- Inflammatory bowel disease
- Sarcoidosis
- Drugs: OCP, Sulphonamides, Penicillin
- Mycobacterial Infections
- Idiopathic
What is dermatitis herpetiformis?
Rare but persistent immunobullous disease that has been linked to coeliac disease
How does dermatitis herpetiformis present?
- Itchy blisters can appear in clusters
- Often symmetry
- Scalp, shoulders, buttocks, elbows and knees
How is dermatitis herpetiformis investigated?
- Detailed history
- Coeliac screening
- Skin biopsy
How is dermatitis herpetiformis treated?
- Emollients
- Gluten free diet
- Topical steroids
- Dapsone
What are the classes of urticarial?
- Acute <6 weeks
- Chronic >6 weeks
What can cause urticarial?
- Viral infection
- Bacterial infection
- Food or drug allergy
- NSAIDS, OPIATES,
- Vaccinations
What is usually the cause of chronic urticaria?
- Idiopathic
- Can be autoimmune
How does urticarial present?
- Wheals/hives
- Associated angioedema (10%)
- Areas of rash can last from few minutes up to 24 hours
What is the treatment for urticarial?
-Withdraw possible triggers
Antihistamines
- Newer generation (desloratadine)
- 3 x daily
-Ranitidine
Montelukast
-Omalizumab
-Ciclosporin
