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