Dermatology Flashcards
Give the pathophysiology of acne vulgaris?
Acne is caused by chronic inflammation with or without localised infection in the pilosebaceous unit.
Acne results from increased production of sebum, trapping of keratin and blockage of the piloseaceous unit.
Why is acne exacerbated by puberty?
androgenic hormones increase the production of sebum, and it improves with anti-androgenic hormonal contraception.
Which bacteria is felt to be the most important in acne vulgaris development?
Propionibacterium acnes bacteria as it colonises the skin. excessive growth of this bacteria can exacerbate acne and many treatments aim to reduce these bacteria.
What are the terms used to describe lesions in acne vulgaris?
Macules: flat marks
Papules: small lumps
Pustules: small lumps with yellow pus
Comedones: skin coloured papules representing blocked pilosebaceous units
Blackheads: open comodones with black center
Ice pick scars
Hypertrophic scars: small lumps that remain after lesions heal
Rolling scars: irregular wave-like irregularities after lesion heals
What is the management of acne vulgaris?
treatment is based on a stepwise fashion:
- no treatment if mild
- Topical benzoyl peroxide reduces inflammation, helps unblock skin and is toxic to P. acnes bacteria
- topical retinouds slow production of sebum
- topical antibiotics
- oral antibiotics
- COCP
- isotretinoin in a last line effective option (oral retinoids)
Describe the usage of isotretinoin in acne vulgaris
It is a retinoid and works by reducing the production of sebum, reducing inflammation and bacterial growth.
Can only be prescribed by a dermatologist as is teratogeic.
What are the side effects of isotretinoin?
- dry skin and lips
- photosensitivity
- depression, anxiet, aggressiona nd suicidal ideation
- rarely SJS and toxic epidermal necrolysis
What is the pathophysiology of arterial ulcers
Occurs due to poor blood supply to the skin due to peripheral arterial disease
What are the distinguishing features of an arterial ulcers?
Absent pulses Pallor Tend to be smaller More regular boarder Grey colour due to poor blood supply Less likely to bleed More painful than venous ulcers Pain at night when legs elevated Pain worse on elevating the leg, improved by hanging
What is the management of arterial ulcers?
- Treating underlying cause
- Good wound care (debridement, cleaning, dressing, abs)
- Tissue viability nurse and district nurse input
- plastic surgery input
What is eczema?
It is a chronic atopic condition caused by defects in the skin barrier leading to inflammation in the skin.
There is a genetic component to eczema however there is no single inheritance pattern.
What is the presentation of eczem?
Usually presents in infancy with dry, red, itchy and sore patches of skin over the flexor surfaces and on the face and neck.
Patients experience periods of flares
What is the pathophysiology of eczema?
Tiny gaps in the skin barrier provide entrance for irritants, microbes and allergens that create an immune response resulting in inflammation and associated symptoms
What is the management for eczema?
EMOLIENTS!!!
Flares can be treated with thicker emollients, topical steroids and treating complications such as infections.
Specialist treatments include:
- zinc impregnated bandages
- topical tacrolimus
- phototherapy
- systemic immunosuppressants
What is the role of topical steroids in eczema?
General rule: weakest steroid for the shortest period required.
SE:
- thinning of the skin
- lead to more flares
- bruising
- tearing
- stretch marks
- telangiectasia
What is the steroid ladder used in eczema?
Mild: Hydrocortisone 0.5%, 1% and 2.5%
Moderate: Eumovate (clobetasone butyrate 0.05%)
Potent: Betnovate (betamethasone 0.1%)
Very potent: Dermovate (clobetasol propionate 0.05%)
HELP EVERY BABY DERMATOLOGIST
What is the most common bacterial infection in eczema?
Staph aureus which is treated with flocloxacillin.
What is Eczema herpeticum?
Viral skin infection in patients with eczema caused by the HSV or VZV.
What is the presentation of eczema herpeticum?
Patient with eczema develops:
- widespread, painful vesicular rash
- with systemic syx such as fever, lethargy, irritability and reduced oral intake.
- lymphadenopathy
What is the management of eczema herpeticum?
Tx usually started based on clinical appearance.
Aciclovir. Mild or moderate = oral whereas more severe = IV aciclovir.
How is eczema herpeticum diagnosed?
Viral swabs of the vesicles can be used to confirm diagnosis but treatment is started based on clinical appearance.
What is basal cell carcinoma?
The most common form of skin cancer but metastasis is rare as they are slow growing.
What are the risk factors for basal cell carcinoma?
- fair skin
- sun exposure
Describe the presentation of basal cell carcinoma
Typically: pearly nodule with a raised, red edge. May be scaly. Often on the face.
What is the treatment for basal cell carcinomas?
Surgical excision is treatment of choice: 3mm margin usually adequate.
Can also be treated topically:
- Imiquimod
- do not treat topically if on head or neck
- cryotherapy may be suitable
Define cellulitis
It is an infection of the skin and the soft tissues.
This is caused due to a breach of the skin barrier which may be due to trauma, eczematous skin, fungal nail infections or ulcers
Describe the presentation of cellulitis
Skin will demonstrate:
- erythema
- hot to touch
- tense
- thickened
- oedematous
- Bullae
- gold-yellow crust can be present and indicate staph aureus infection
What are the causes of cellulitis?
Most common causes:
- Staph. aureus
- Group A strep
- Group C strep
Other causes:
- MRSA
What is the eron classification used for?
It is the classification for severity of cellulitis:
- No systemic toxicity or comorbidity
- systemic toxicity or comorbidity
- Significant systemic toxicity or significant comorbidity
- Sepsis or life-threatening.
Class 3 or 4: IV antibiotics
What is the treatment of celllulitis?
First line: Flucloxacillin 500mg
Others:
- clarithromycin
- clindamycin
- co-amoxiclav
What are the two main types of contact dermaittis?
- irritant contact dermatitis
2. Allergic contact dermatitis
Describe the features of irritant contact dermatitis
- common
- non-allergic reaction due to weak acids or alkalis
- often seen on the hands
- erythema is typical
- crusting and vesicles are rate
Describe the features and management of allergic contact dermatitis
- Type IV hypersensitivity reaction
- Uncommon
- often seen on the head following hair dyes
- presents as an acute weeping eczema which predominately affects the margins of the hairline rather than the hairy scalp itself
- Topical treatment with potent steroid is indicated
Define the causative agents of cutaneous fungal infections
fungal infections of the body are tinea corporis and of the groin is tinea cruris
Primary caused by dermatophytes such as trichophyton rubrum
What are the risk factors for cutaneous fungal infections?
- hot humid environments
- wearing tight fitted clothing
- obesity
- hyperhidrosis
Describe the diagnosis of cutaneous fungal infections?
Based on clinical features:
- scaly, itchy skin
- there may be single or multiple red or pink, flat or slightly annular patches varying sizes
- typically lesions have an active red, scaly advancing edge and a clear central area
Describe the assessments of suspected cutaneous fungal infections?
- history
- Examination of pattern, extent and severity
- skin sampling for fungal microscopy and culture
What is the initial management for cutaneous fungal infections?
- advice on self-care
- advice on tx with topical anti-fungal cream
- prescribing short-term corticosteroid e.g. hydrocortisone
- consider oral anti-fungal e.g. terabinafine first line depending on fungal microscopy
- managing concomitant fungal infection elsewhere to reduce risk of reinfection
What is the treatment for persistant signs of infection in cutaneous fungal infections?
- manage non-adherance
- skin sampling for fungal microscopy and culture
- oral anti-fungal treatment based on microscopy
Define cutaneous warts
small, rough growths that are caused by infection of kertainocytes with HPV.
Common in infants and very young children
How are cutaneous warts transmitted?
Skin-to-skin contact or indirectly via contact with contaminated floors or surfaces
Describe the presentation of cutaneous warts
- common warts are firm and raised with a rough surface
- periungal warts are common around the nails and can be painful
- plane warts usually round, flat-topped and skin coloured
- Palmer and plantar warts grow on palms and the soles of the feet (verrucae).
How are cutaneous warts diagnosed?
Based on clinical appearance
What is the management of cutaneous warts?
Usually resolve without treatment.
- advice on reducing risk of transmission
- tx options for non-facial warts in adults: salicylic acid, cryotherapy
Define dermatitis herpatiformis
A rare but persistent immunibullous disease that has been linked to coeliac disease
What is the genetic link with dermatitis herpetiformis?
genetic predisposition with an association with (HLA) DQ2 and DQ8