Case 9 Psoriasis, Dermatitis Flashcards
General histories for dermatology
Presenting complaint
- Site and duration
- Initial appearance and evolution of rash
- Onset of rash: specific triggers, aggregating or relieving factors
- Site of rash: unilateral/bilateral
- Character of lesion: itch, pain
- Crouse of rash: constant, come and go
PMHx
- History of atopy: atopic triad
- Medication, especially any recent changes
- Family history of skin disease
Social history
- Occupation/any improvement of lesion when away from work
- new changes to shampoo/detergents
General physical exams for dermatology
- General observations (SCAM) Size, shape Colour Associated secondary change Margin, morphology - If the lesion is pigmented (ABCDE), melanoma Asymmetry Border irregular Colours 2 or more Diameter > 6 mm Elevation - Palpate Surface, consistency, mobility, tenderness, temperature
What are some characteristics of psoriasis?
Pink papules/plaques covered by loosely adherent silver-white scales
less itchy comparing to eczema
What are some risk factors of psoriasis?
- Genetic: ask about family history of psoriasis/psoriatic arthritis
- Trauma, previous infection
- Drug eruption, smoking
- HIV, stress
- Medication: lithium, beta blockers
- Might worse in winter due to lack of sun and humidity
What is the mechanism of psoriasis?
AUTO-IMMUNE
When skin breaks and pathogen invades, dendritic cells present the antigen to T cells, who release cytokines –> excessive inflammation –> inc keratinocytes proliferation in the skin (parakeratosis, scaly appearance) + recruitment of immune cells (collection of neutrophils in the stratum corneum layer)
Excessive inflammation –> vasodilation of blood vessels between dermis and epidermis –> inc recruitment of immune cells such as neutrophils –> neutrophils collect in the stratum corneum layer
Excessive inflammation –> excessive keratinocytes proliferation and abnormal maturation –> thinning of stratum Basale and thickens the other layers especially stratum corneum and stratum spinosum –> keratinocytes retain nuclei (parakeratosis) and do not adhere to each other properly (breaks in epidermis leading to the scaly appearance ) –> When scales are picked off, blood vessels in dermis can get injured and cause localised spots of bleeding called auspitz sign
What are some symptoms and signs of psoriasis?
- Erythema superficial elongated and dilated capillaries
- Thickening thicker epidermis/acanthosis
- Scale – abnormal keratinisation
- Auspitz sign – removing scale reveals wet surface with pinpoint bleeding
- Less itchy than eczema, well-demarcated than eczema
- Symmetrical – scalps, elbows, knees, lumbosacral
What are some comorbidities of psoriasis?
- 10-15% people develop psoriatic arthritis: ask about joint pain/swelling or finger pain
- Inc risk of CVS ,renal disease
- Metabolic syndrome central obesity, impaired glucose tolerance, dyslipidaemia, hypertension
- Crohn’s disease/IBD
- Depression/psychosocial issues, low self-esteem, social isolation, sexual dysfunction, suicidal ideation in 10%
- Dec vocational opportunities and economic impact
- Depression and stress triggers flares and reduce motivation to improve health
How to diagnose psoriasis?
- Usually clinical
- Tissue biopsy to look for the classic change in epidermal layers
Acanthosis (epidermal thickening), parakeratosis (retention of nuclei in stratum corneum), accumulation of neutrophils in superficial epidermis, dilated capillaries
What are some treatment of psoriasis
- Avoid triggers: stress, medication (NSAIDs, beta blockers, lithium, ACE inhibitors)
- Moisturisers: clear plaques and minimise itchiness
- Topical corticosteroids
- Topical calcipotriol
- Keratolytic agents: urea, salicylic acid, fruit acid
- Vit D (Calcipotiol)
Inhibits hyperproliferation and abnormal differentiation - UV therapy (dermatology day unit) induce DNA damage in keratinocytes
- Coal tar preparations
Suppress DNA synthesis, reduce epidermal thickness - Depression and anxiety psychological counselling/psycho-dermatology
Why is oral preferred over topical?
When rash is wide-spread, oral antibiotics are usually preferred over topical –> several tubes are needs to cover all infected areas + costs –> lead to incorrect application techniques and non-adherence
Rash due to hypersensitivity to penicillin?
Urticaria
Acute onset, after antibiotics
angioedema/swollen face, anaphylaxis (SOB)
What are some characteristics of eczema/atopic dermatitis?
Dry, itchy and erythematous patches, vesicular and weepy, poorly defined
What is the mechanism of atopic dermatitis?
inflammatory condition: Type 1 hypersensitivity (IgE-mediated, prior sensitisation leading to degranulation of mast cells + HISTAMINE RELEASE)
- Epidermal barrier dysfunction due to genetics
Dec filaggrin, which is a protein that holds skin together (25-50%)
In proteases, inc breakdown due to pathogens invasions
Abnormal stratum corneum lipids - Immune dysfunction
Predominant Th2 cell response –> IL 4, 5 and 13 cytokine release –> stimulate isotope switching to IgE –> eosinophils and mast cell degranulation
What are some risk factors of eczema?
- Atopic triad or family history of atopy/eczema
- Allergic rhino-conjunctivitis, eosinophilic oesophagitis
- Food allergies
What are some triggers of eczema?
Airborne allergens: house dust mites, animal feathers, moulds, pollens, fragrances
Food allergens: egg, milk, soy, peanuts, fish
Irritants: prolonged water immersion, soap, shampoo, chlorinated pools, clothing (laundry, detergent, wool, synthetic fibres)
Climate: temp extremes, low humidity, +/- sunlight
Microbes (bacteria, fungi, viruses)
