Skin Rashes Flashcards
What is psoriasis?
A papule-squamous disorder characterised by red, scaly plaques. The skin becomes inflamed and hyper-proliferates at about 10x the normal rate.
Who gets psoriasis?
Age of onset has 2 peaks- 16-22 yr olds and 55-60 yr olds. There is a genetic basis but this is not fully understood.
What is Auspitz’s sign?
the appearance of punctate bleeding spots when psoriasis scales are scraped off
Describe chronic plaque psoriasis
This is the most common type characterised by well defined, scaly, erythematous plaques usually seen on extensor surfaces. Lesions can be itchy and/or sore.
What is Koebner pneumonon?
New plaques occur at sites of skin trauma
Describe flexural psoriasis
Usually occurs later in life. There is often less scaling.
Describe guttate psoriasis
Raindrop like psoriasis where an explosive eruption of very small circular oval plaques appears over the trunk, usually 2 weeks after strep sore throat.
Describe erythrodermic and pustular psoriasis
Most severe types with widespread, intense inflammation of the skin. This can be life threatening.
Describe palmoplantar psoriasis
Localised pustular psoriasis confined to hands and feet, no severe systemic symptoms, usually occurs in heavy smokers.
Describe psoriatic nail disease
Usually get oncycholysis (nail separates from skin underneath it), nail putting, subungal hyperkeratosis and dystrophy.
Describe the pathology of psoriasis
Biopsy will show epidermal acanthosis and parakeratosisi due to increased skin turnover. The granular layer is often absent. Polymorphonuclear abscesses may be seen in the upper epidermis. The epidermal rete ridges appear elongated and clubbed as they fold down into the dermis.
3 complications of psoriasis?
Greatly impairs quality of life
Some 5-10% of individuals develop psoriatic arthritis
Psoriasis patients have a higher prevalence of cardio metabolic diseases
When are emollients used in psoriasis?
everyone
When are vitamin D analogues used for psoriasis?
Localised plaques. Calcipotrol used on extensor surfaces and calcitrol usually used on flexural surfaces. Need to be careful of hypercalcaemia.
When is coal tar used in psoriasis?
Anywhere- no limit but usually patients don’t like this treatment
When are steroids used in psoriasis?
Usually given in combination as there is a risk of rebound psoriasis
When is phototherapy used in psoriasis?
Usually when topical treatments have not worked
Describe systemic treatments for psoriasis
Immunosuppression by methotrexate or immune modulation by biological agents
When is dithranol used in psoriasis?
In localised plaques if patient complies, it is messy and time consuming, short contact as have to wash off and it stains patients clothes.
Define discoid eczema
Well defined probably atopic too. Staph infection is very common in this type of eczema
What is eczema?
Itchy, ill-defined, erythematous, scaly rash, lots of types
What is allergic contact dermatitis/ eczema?
Immune response to chemicals, topical therapies, nickel, plants etc.
What type of hypersensitivity is allergic contact dermatitis?
4
What investigations are done in allergic contact dermatitis?
Patch testing to diagnose contact allergy
Management of allergic contact and irritant dermatitis?
Avoid allergy or irritant, protective clothing, manage the eczema rash with same as atopic
What is irritant dermatitis?
This is not immune mediated and is caused by non-specific irritation. Can be difficult to distinguish from allergic and often the 2 occur together.
How is atopic eczema usually distributed?
Usually has a flexural distribution (in babies this is different)
What factors make someone susceptible to eczema?
Other atopic diseases eg asthma, hay fever, food allergy. Associated with filaggrin gene and environmental factors
How does eczema look different in skin of colour?
Erythema is harder to see, more defined papule and more extensive lichenification
What chronic changes can occur in atopic eczema?
lichenification (thickening), excoriation (breaks in skin from scratching) and secondary infection (usually Staph A)
What is infection of eczema by herpes virus called? How does it present?
Eczema herpeticum. High temperature, very painful monomorphic punched-out lesions, systemically unwell child.
Treatment of eczema?
Plenty of emollients Avoid irritants including shower gels and soaps Topical steroids Treat any infection Phototherapy- mainly UVB Systemic immunosuppressants
Pathology of eczema?
Spongiosis- oedema between keratinocytes
Inflammatory cell infiltrate- acute or chronic lymphocytes and/or neutrophils.
Describe photosensitive eczema
skin is irritated by sunlight. note the difference in rashes in those taking photosensitive drugs
Describe stasis eczema?
Caused by hydrostatic pressure, oedema and red cell extravasation making skin easily irritated and damaged
Describe seborrhoiec eczema
Cradle cap in babies
Describe pompholyx eczema
Acute form with inflammation
Describe lichen simplex eczema
excessive scratching of healthy skin causes trauma and eczema
What is acne vulgaris?
Chronic inflammatory disease of the pilosebaceous unit.
Describe pathogenesis of acne vulgaris
Lesions arise in the pilosebaceous follicle which becomes blocked due to abnormal keratinisation and increased production of sebum. This leads to overgrowth of propionibacterium acnes which triggers an inflammatory response activation of Toll-like receptors and induction of pro-inflammatory cytokines.
Who presents with acne?
14-17 yr olds in females. 16-19 yr olds in males. May persist in adulthood.
Presentation of acne vulgaris?
Occurs in the face and upper torso where the sebaceous glands are very dense. Non- inflammatory features= blackheads (open comedones) or whiteheads (closed comedones). Inflammatory features are papule, pustules, nodules, cysts. Secondary features are scarring.
Treatment of acne vulgaris?
Avoid oily substances
TOPICAL TREATMENTS
1- benzoyl peroxids (keratolytic and antibacterial)
2- retinoid (drying effect) Tretinoin.
Isotretinoin, Adapalene.
3- topical antibiotic (anti-bacterial and anti inflammatory)
SYSTEMIC TREATMENTS
4- antibiotics usually tetracyclines
5- isotretinoin (oral retinoid loads of side effects)
What is rosacea?
An inflammatory rash with no comedones
Who usually gets rosacea?
Mid adult life- the cause is unknown potentially related to the demodex mite
Presentation of rosacea
rash on nose, chin, cheeks and forehead
Prominent facial flushing exacerbated by sudden change in temperature, alcohol or spicy food.
May get enlarged nose
Treatment of rosacea?
Reduce aggravating factors, avoid steroids.
Topical metronidazole, ivermectin
Oral tetracycline long term, low dose isotretinoin if severe
For telangiectasia use vascular lazer
For rhinopehyma surgery or laser shaving
What are bullous disorders? Give two examples
Blistering. Auto-immune diseases where damage to adhesion mechanisms in the skin results in blistering at various levels.
Describe four differences between bullous pemphigoid and pemhigus vulgaris
Bullous pemphigoid Large tense bullae Nikolsky sign negative Mucosal lesions unlikely Sub epidermal blister with no evidence of acantholysis
Pemphigus Vulgaris
Thin vesicles that usually rupture to leave raw areas
Nikolsky sign positive
Mucosal involvement is very common
Intra epidermal blister with acantholysis (loss of desmosomes so keratinocytes float away from each other)
What is Nikolskys sign?
This is when the top layer of skin slips away from lower layers when rubbed.
Pemphigoid or pemphigus has a high mortality if left untreated?
Pemphigus has high mortality if left untreated. Pemphigoid has much lower risk.
How do you investigate pemphigoid and pemphigus?
Skin biopsy with direct immunofluorescence and indirect immunofluorescence
Treatment of pemphigoid and pemphigus
Treat with systemic steroids and other immune-suppressive agents. In pemphigoid you can use tetracyclines. Topical treatments such as emollients, topical steroids, topical anti-sepsis and hygiene measures
What is lichen planus?
T cell mediated inflammation targeting an unknown protein within the skin and mucosal keratinocytes.
Who gets lichen planus?
Occurs in middle age
Presentation of lichen planus?
Rash consisting of intensely pruritic, purple-pink, polygonal papule. Typically effects volar wrists/ forearms, shins and ankles. Wickham’s striae. Mucosal and mucosal genital involvement is common.
What are wickham’s striae?
Whitish lines visible in the papule of lichen planus
Pathology of lichen planus?
Lichenoid disorders are characterised by damage to the basement epidermis. Irregular sawtooth acanthuses, hypergranulosis, orthohyperkeratosis. Bandlike upper dermal infiltrate of lymphocytes. Basal damage with formation of cytoid bodies.
Histologically what are lichenoid disorders characterised by?
Damage to the basement epidermis
How long does lichen planus usually last for?
12-18 months before burning out (however quite distressing so usually give treatment)
Treatment of lichen planus?
Check for possible drug precipitant, emollients, topical steroids or oral if extensive. UVB phototherapy or PUVA.
What is first line treatment of rosacea?
Topical metronidazole gel (if that doesn’t work move onto oral tetracycline)
What may person presenting with bullous pemphigoid have months history of preceding the blistering rash?
Itch
Describe dermatitis artefacta
Dermatitis artefacta is a condition in which skin lesions are solely produced or inflicted by the patient’s own actions. This usually occurs as a result or manifestation of a psychological problem. It could be a form of emotional release in situations of distress or part of an attention seeking behaviour. Variable and bizzare histology.
