Dermatology Flashcards
What is psoriasis
a chronic inflammatory skin condition characterised by clearly defined, red and scaly plaques
What causes psoriasis?
Psoriasis is a multifactorial, immune-mediated genetic skin disease involving interactions between the innate and adaptive immune systems
What are the clinical features of psoriasis?
- Symmetrically distributed, red, scaly plaques with well-defined edges, often silvery white
- common sites on the scalp, elbows, and knees.
- Auspitz sign - small points of bleeding when plaques are scraped off
- Koebner phenomenon - development of psoriatic lesions on areas of skin affected by trauma
- Residual pigmentation of the skin after the lesions resolve
What nail signs are seen in psoriasis with nail involvement
- pitting
- onycholysis
- yellowing
- subungual hyperkeratosis
- loss of the nail
Describe 4 subtypes of psoriasis
- plaque psoriasis: typical well-demarcated red, scaly patches affecting the extensor surfaces, sacrum and scalp
- flexural psoriasis: affects body folds and genitalia. smooth, well-defined patches
- guttate psoriasis: typically 2-4w post-streptococcal infection. widespread small, red plaques on the body ( teardrop lesions)
- pustular psoriasis: commonly occurs on the palms and soles
What is the most common form of psoriasis
Chronic plaque psoriasis
What distinguishes small plaque psoriasis from large plaque psoriasis?
Small plaque psoriasis has plaques <3 cm, while large plaque psoriasis has plaques >3 cm.
Give 5 factors that may aggravate psoriasis
- Streptococcal infection
- stress
- alcohol
- trauma - cuts, abrasions or sunburn
- Drugs - e.g. lithium, beta-blockers, ACEi and NSAIDs
- withdrawal of steroids
How does sun exposure impact psoriasis?
typically improves psoriasis
What health conditions are commonly associated with psoriasis?
- Psoriatic arthritis
- IBD
- uveitis
- CVD (atherosclerosis)
- metabolic syndrome - obesity, HTN, T2DM, hyperlipidaemia
What general advice should patients with psoriasis follow?
- Smoking cessation
- limit alcohol consumption
- maintain optimal weight.
First line management of chronic plaque psoriasis
- a potent topical corticosteroid applied OD plus vitamin D analogue applied OD
- should be applied separately, one in the morning and the other in the evening
- for up to 4 weeks as initial treatment
- regular emollients may help to reduce scale loss and reduce pruritus
Second line management of chronic plaque psoriasis
if no improvement after 8w of first line treatment offer:
* vitamin D analogue (e.g., calcipotriol) twice daily - this can be used long-term
Third line management of chronic plaque psoriasis
If no improvement after 8-12 weeks of 2nd line treatment, offer either:
* a potent corticosteroid applied twice daily for up to 4 weeks, or
* a coal tar preparation applied once or twice daily
* consider short-acting dithranol (wash off after 30 mins)
Describe the secondary care management of chronic plaque psoriasis
Phototherapy:
* narrowband UVB light - 3x per week
* photochemotherapy is also used - psoralen + ultraviolet A light (PUVA)
Systemic therapy:
* oral methotrexate is used first-line
* ciclosporin
* systemic retinoids (e.g. acitretin)
* biologics - TNF-alpha inhibitors (e.g., adalimumab, infliximab, etanercept)
* IL-17/IL-23 inhibitors (e.g., ustekinumab).
Adverse effects of phototherapy in psoriasis treatment
- skin ageing
- squamous cell cancer
Management of scalp psoriasis
- potent topical corticosteroids used once daily for 4 weeks
if no improvement after 4 weeks then either use: - different formulation of the corticosteroid (e.g., a shampoo or mousse) and/or
- a topical agent to remove adherent scale (e.g., agents containing salicylic acid, emollients and oils) before application of the potent corticosteroid
Management of face, flexural and genital psoriasis
mild or moderate potency corticosteroid applied once or twice daily for a maximum of 2 weeks
What is acne vulgaris
the common form of acne, characterised by a mixed eruption of inflammatory and non-inflammatory skin lesions
Explain the pathophysiology of acne
- follicular epidermal hyperproliferation resulting in the formation of a keratin plug
- This in turn causes obstruction of the pilosebaceous units (contains the hair follicles and sebaceous glands)
- colonisation by the anaerobic bacterium Propionibacterium acnes
- overall inflammation
Where does acne vulgaris most commonly affect the body?
Primarily the face, but it can also involve the neck, chest, back, and more extensive areas
What are the superficial lesions of acne?
- Open and closed comedones (blackheads and whiteheads)
- Papules (small, tender red bumps) - inflammatory
- Pustules (small, white or yellow squeezable spots) - inflammatory
What are the deeper lesions of acne?
- Nodules (large painful lumps)
- pseudocysts (fluctuant swellings).
What are some secondary lesions associated with acne?
- Excoriations
- Ice pick scars are small indentations in the skin that remain after acne lesions heal
- Hypertrophic scars are small lumps in the skin that remain after acne lesions heal
- erythematous macules (flat marks)
- pigmented macules
How long do individual acne lesions typically last?
Usually less than 2 weeks, but deeper papules and nodules may persist for months
What is considered mild acne vulgaris
open and closed comedones with or without sparse inflammatory lesions
What is classified as moderate acne vulgaris
widespread non-inflammatory lesions and numerous papules and pustules
What is classified as severe acne
extensive inflammatory lesions, which may include nodules, pitting, and scarring
How is mild-moderate acne managed
12-week course of topical combination therapy, such as:
* Fixed combination of topical adapalene with topical benzoyl peroxide
* topical tretinoin with topical clindamycin
* benzoyl peroxide with topical clindamycin
What treatment options are available for moderate to severe acne?
12-week course of one of the following fixed combos:
* topical adapalene with topical benzoyl peroxide
* topical tretinoin with topical clindamycin
* topical adapalene with topical benzoyl peroxide + either oral lymecycline or oral doxycycline
* a topical azelaic acid + either oral lymecycline or oral doxycycline
What important points should be considered with oral antibiotic usage for acne?
- Tetracyclines: Avoid in pregnant/breastfeeding women and children under 12; erythromycin may be used in pregnancy.
- Limit antibiotic treatment (topical/oral) to 6 months unless exceptional circumstances
- Co-prescribe topical retinoids or benzoyl peroxide with oral antibiotics to reduce antibiotic resistance
How are contraceptives used in acne treatment for women?
- COCP can be used as an alternative to oral antibiotics and should be used with topical agents
- Dianette (co-cyprindiol) has anti-androgen properties but carries an increased risk of VTE, so it should be used second-line for 3 months, with counseling about risks
What is the protocol for using oral isotretinoin?
should only be prescribed under specialist supervision. Pregnancy is a contraindication for both topical and oral retinoid treatments.
What treatments should be avoided to reduce the risk of antibiotic resistance in acne?
- Monotherapy with a topical antibiotic
- Monotherapy with an oral antibiotic
- A combination of a topical antibiotic and an oral antibiotic
When should a referral for acne treatment be considered?
- Mild to moderate acne not responding to two completed courses of treatment
- Moderate to severe acne not responding to previous treatment with an oral antibiotic
- Acne with scarring
- Acne with persistent pigmentary changes
- Acne causing or contributing to persistent psychological distress or mental health disorders
What is herpes zoster
localised, blistering and painful rash caused by reactivation of varicella-zoster virus (chickenpox)
- aka shingles
Explain the pathophysiology of herpes zoster
After primary infection, VZV remains dormant in dorsal root ganglia nerve cells in the spine for years before it is reactivated and migrates down sensory nerves to the skin to cause herpes zoster.
Give 3 RFs for herpes zoster
- increasing age
- HIV
- Immunosuppression conditions (steroids, chemo)
What are the clinical features of herpes zoster
- burning pain over affected dermatome for 2-3 days
- fever, headache, localised lymphadenopathy
- unilateral, initially erythematous, macular rash over affected dermatome
- rash quickly becomes vesicular as new lesion erupt
What are the most commonly affected dermatomes in shingles
T1-L2
How is shingles diagnosed
The diagnosis is usually clinical
How is herpes zoster managed
- should be advised that they are infectious until the vesicles have crusted over, usually 5-7 days following onset
- NSAIDs and paracetemol
- amitriptyline if unresponsive to above
- protective ointment (petroleum jelly)
- antivirals (oral aciclovir) within 72 hours of onset
- oral corticosteroids may be considered if other analgesia doesn’t work
What are one of the benefits of prescribing antiviral in older people with shingles
reduced incidence of post-herpetic neuralgia
Give 3 complications of herpes zoster
- post-herpetic neuralgia (mc)
- herpes zoster ophthalmicus
- ramsay hunt syndrome - facial paralysis and ear lesions
What is Herpes zoster ophthalmicus
reactivation of the varicella-zoster virus in the area supplied by the ophthalmic division of the trigeminal nerve
Management of Herpes zoster ophthalmicus
- oral antiviral treatment for 7-10 days: ideally started within 72 hours
- ocular involvement requires urgent ophthalmology review
What is post-herpetic neuralgia
persistence or recurrence of pain in the same area, more than a month after the onset of herpes zoster.
mc with older age
What causes scabies
the mite Sarcoptes scabiei
How is scabies spread
prolonged skin contact
Features of scabies
- widespread pruritus
- linear burrows on the side of fingers, interdigital webs and flexor aspects of the wrist
- in infants, the face and scalp may also be affected
- secondary features due to scratching: excoriation, infection
What causes the intense pruritus in scabies
due to a delayed-type IV hypersensitivity reaction to mites/eggs which occurs about 30 days after the initial infection
How is scabies managed
- permethrin 5% is first-line
- malathion 0.5% is second-line
- give appropriate guidance on use
- pruritus persists for up to 4-6 weeks post eradication
What guidance should be given to patient treated for scabies
- avoid close physical contact with others until treatment is complete
- all household and close physical contacts should be treated at the same time, even if asymptomatic
- launder, iron or tumble dry clothing, bedding, towels, etc., on the first day of treatment to kill off mites
What is eczema herpeticum
severe primary infection of the skin by herpes simplex virus 1 or 2.
Features of eczema herpeticum
- often presents as a rapidly progressing painful rash/ eczema
- monomorphic punched-out erosions (circular, depressed, ulcerated lesions) usually 1-3 mm in diameter
How is eczema herpeticum managed
Potentially life threatening: children should be admitted for IV aciclovir
What is Pityriasis Rosea?
acute, self-limiting rash that primarily affects young adults
What virus is thought to play a role in Pityriasis Rosea?
herpes hominis virus 7 (HHV-7)
Features of Pityriasis Rosea?
- a minority may give a history of a recent viral infection
- herald patch (usually on trunk)
- followed 1-2 weeks later by multiple erythematous, slightly raised oval lesions with a fine scale confined to the outer aspects of the lesions
How is Pityriasis Rosea managed?
self-limiting - usually disappears after 6-12 weeks
