Skin Diseases & Disorders
Skin Anatomy Stratum corneum Stratum germinativum Keratin Melanin Sebaceous glands Sudoriferous glands Hair follicles
Structure of the skin
Skin Lesions
Flat: maculesElevated:
Solid: papules, nodules, wheals, tumorsLiquid-filled: vesicles, bullae, pustules, cysts
What is psoriasis?
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Inflammatory and hyperplastic disease of skin1
Characterised by erythema and elevated scaly plaques1
Chronic, relapsing condition
Course of disease often unpredictable
1. Dermatology Expert Group. Therapeutic guidelines: dermatology. Version 3. Melbourne: Therapeutic Guidelines Limited, 2009.
Epidemiology Common skin disorder
Prevalence variable: ~ 0.3–2.5%1
Prevalence equal in males and females2
Estimated incidence: ~ 60 per 100,000 per year3
1. Plunkett A et al. Australas J Dermatol 1998; 39: 225–232. 2. Griffiths CEM et al. In: Burns T et al., eds. Rook’s textbook of dermatology. 8th ed. UK: Blackwell Publishing Ltd, 2010. 3. Bell LM et al. Arch Dermatol 1991; 127: 1184–7. 6
Age of onset Mean age: ~ 23–37 years1
Current theory: 2 distinct peaks with possible genetic associations1
Early onset (16–22 years)2
More severe and extensive More likely to have affected first-degree family member
Late onset (57–60 years)2
Milder form Affected first-degree family members nearly absent
1. Plunkett A et al. Australas J Dermatol 1998; 39: 225-232. 2. Henseler T et al. J Am Acad Dermatol 1985; 13:450-6. 7
Genetic influence Evidence suggests strong
genetic association Studies of monozygotic twins show
concordance for psoriasis (e.g. 64% in a Danish Study)1
Multiple susceptibility loci have been identified2
Disease expression – likely result of genetic and environmental factors2
1.Brandup F et al. Acta Dermato-Vernerol 1982; 62L: 229–36. 2. Barker J. Clin Exp Dermatol 2001; 26(4): 321–5. 8
Common trigger factors for psoriasis1
Infections (e.g. streptococcal, viral) Skin trauma (Koebner phenomenon) Psychological stress Drugs (e.g. lithium, beta blockers) Sunburn Metabolic factors (e.g. calcium
deficiency) Hormonal factors (e.g. pregnancy)
1. Dermatology Expert Group. Therapeutic guidelines: dermatology. Version 3. Melbourne: Therapeutic Guidelines Limited, 2009. 9
Psoriasis is a T-cell mediated, autoimmune disease1
Current hypothesis:
Unknown skin antigens stimulate immune response
Antigen-specific memory T-cells are primary mediators
Leads to impaired differentiation and hyperproliferation of keratinocytes
1. Lee M et al. Australas J Dermatol 2006; 47: 151–9. 10
Clinical presentation: classic psoriasis
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Well-defined and sharply demarcated
Round/oval-shaped lesions
Usually symmetrical
Erythematous, raised plaques
Covered by white, silvery scales
Common sites affected by psoriasis
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Can affect any part of the body – typically scalp, elbow, knees and sacrum1
Extent of disease varies
1. Menter A et al. Fast facts: psoriasis. 2nd ed. Oxford: Health Press, 2004.
Types of psoriasis Chronic plaque Guttate Flexural Erythrodermic
Pustular Localised and generalised
Local forms Palmoplantar Scalp Nail (psoriatic
onychodystrophy)
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1. van de Kerkhof P, ed. Textbook of psoriasis. 2nd ed. Melbourne: Blackwell Publishing, 2003. 2. Rossi S, ed. Australian medicines handbook. Adelaide: AMH, 2010.
Chronic plaque psoriasis
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Most common type – affects approximately 85%1
Features pink, well-defined plaques with silvery scale2
Lesions may be single or numerous2
Plaques may involve large areas of skin2
Classically affects elbows, knees, buttocks and scalp3
1. Menter A et al. Fast facts: psoriasis. 2nd ed. Oxford: Health Press, 2004. 2. Dermatology Expert Group. Therapeutic guidelines: dermatology. Version 3. Melbourne: Therapeutic Guidelines Limited, 2009. 3. Weller PA. Psoriasis. In: Marks R, ed. MJA practice essentials – dermatology. 2nd ed. Sydney: Australasian Medical Publishing Company, 2005.
Guttate psoriasis
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Numerous and small lesions – ~ 1 cm diameter
Pink with less scale than plaque psoriasis
Commonly found on trunk and proximal limbs
Typically seen in individuals < 30 years
Often preceded by an upper respiratory tract streptococcal infection1. Dermatology Expert Group. Therapeutic guidelines: dermatology. Version 3. Melbourne: Therapeutic Guidelines Limited,
2009. 2. Menter A et al. Fast facts: psoriasis. 2nd ed. Oxford: Health Press, 2004. 3. Weller PA. Psoriasis. In: Marks R, ed. MJA practice essentials – dermatology. 2nd ed. Sydney: Australasian Medical Publishing Company, 2005. 4. Menter A et al. J Am Acad Dermatol 2008; 58(5): 826–50.
Flexural psoriasis
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Lesions in skin folds1
Particularly groin, gluteal cleft, axillae and submammary regions
Often minimal or absent scaling
May cause diagnostic difficulty when genital or perianal region is affected in isolation
Erythrodermic psoriasis
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Generalised erythema covering entire skin surface
May evolve slowly from chronic plaque psoriasis or appear as eruptive phenomenon
Patients may become febrile, hypo/hyperthermic and dehydrated
Complications include cardiac failure, infections, malabsorption and anaemia
Relatively uncommon
Pustular psoriasis
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Two forms: Localised form More common Presents as deep-
seated lesions with multiple small pustules on palms and soles
Generalised form Uncommon Associated with fever
and widespread pustules across inflamed body surface3
Palmoplantar psoriasis1
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Can be hyperkeratotic or pustular
May mimic dermatitis – look for psoriatic manifestations elsewhere to aid diagnosis
Possibly aggravated by trauma
1. Dermatology Expert Group. Therapeutic guidelines: dermatology. Version 3. Melbourne: Therapeutic Guidelines Limited, 2009.
Scalp psoriasis
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Varies from minor scaling with erythema to thick hyperkeratotic plaques1,2
May extend beyond hairline1,2
Patient scratching may produce asymmetric plaques2
1. Dermatology Expert Group. Therapeutic guidelines: dermatology. Version 3. Melbourne: Therapeutic Guidelines Limited, 2009. 2. Menter A et al. Fast facts: psoriasis. 2nd ed. Oxford: Health Press, 2004.
Nail psoriasis1
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May be present in patients with any type of psoriasis
Can take several forms:
Pitting: discrete, well-circumscribed depressions on nail surface
Subungual hyperkeratosis: silvery white crusting under free edge of nail with some thickening of nail plate
Onycholysis: nail separates from nail bed at free edge
‘Oil-drop sign’: pink/red colour change on nail surface
1. Menter A et al. Fast facts: psoriasis. 2nd ed. Oxford: Health Press, 2004.
Urticaria (Hives) Also called wheals Episodic inflammatory, allergic
reaction in a localized area of skin Majority of cases are acute, not
chronic Migratory lesions Itchy, raised, erythematous, warm
lesions that blanch when pressed
Urticaria Localized capillary dilation & fluid
transudation Histamine is most important chemical
mediator Up to 20% population has had at least
one episode in lifetime Treatment: antihistamines,
epinephrine, steroids, avoidance of allergens
Acne Vulgaris Inflammatory disease of sebaceous
glands and hair follicles Characterized by comedos,
papules, pustules Typically appears during puberty More severe forms in males More persistent in females May involve scarring
Acne Vulgaris Sebaceous gland plugged by
cornified cells Sebaceous secretions continue,
increasing size of lesion Treatment: Vit A, benzoyl
peroxide, tetracycline, erythromycin, estrogen, Accutane (related to Vit A), drying or pealing agents, topical antibiotics
Alopecia Absence or loss of hair, most
notable on the head Etiologies: numerous
Systemic diseases or treatments Types
Scarring: fibrosis & loss of follicles Non-scarring: no follicle loss,
reversible
Alopecia
Types:GeneralizedLocalized
Male pattern baldnessfrontotemporal loss, then
midfrontal recession and near vertexFemale pattern baldness
central scalp
Alopecia Treatment
Minoxidil Treatment of androgen levels Autografting, etc
Dermatitis A range of inflammatory diseases
of the skin Typically have erythema, pruritis,
and a variety of skin lesions May be acute, subacute, or chronic Some types
Seborrheic, contact, atopic
Contact Dermatitis Caused by direct contact of irritative
substance or contact with substance to which patient is allergic or sensitive Drugs, plants, additives, latex, wool, etc.
S/S: erythema, warmth, edema, vesicles
Dx: via patch test, allergy testing Rx: usually self-limiting, avoidance
Latex Allergy Range of hypersensitivity reactions to
latex, a product derived from rubber May be contact dermatitis, urticaria,
GI symptoms, facial symptoms, anaphylactic shock
Higher risk: frequent contact with latex products, asthma hx, banana, avocado, or topical fruit allergy
Latex Allergy Dx: serum test for IgE for latex
and via clinical signs Treatment: avoidance,
epinephrine if needed
Atopic Dermatitis Skin inflammation of unpredictable
course Highest incidence in children
3-5% population by 5 YOA 70% have family history of
asthma, allergic rhinitis, atopic dermatitis
Eczema More generic term than used in
this textbook Most common inflammatory skin
disease May be acute, subacute, chronic Components:
Erythema, scales, vesicles
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