1. Skin Diseases & Disorders

2. Skin Anatomy Stratum corneum Stratum germinativum Keratin Melanin
Sebaceous glands
Sudoriferous glands
Hair follicles

3. Structure of the skin

4. Skin Lesions Flat: macules Elevated:
Solid: papules, nodules, wheals, tumors
Liquid-filled: vesicles, bullae, pustules, cysts

5. What is psoriasis? 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.

6. 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
Additional notes
Prevalence ( %) – derived from estimates of psoriasis prevalence made in cross-sectional studies1. Prevalence varies according to race and geographical location2.
60 per 100,000 incidence rate (sex and age adjusted) was reported from a four-year population based study conducted in Rochester, Minnesota3.
1. Plunkett A et al. Australas J Dermatol 1998; 39: 225– Barker J. Clin Exp Dermatol 2001;26(4): Bell LM et al. Arch Dermatol 1991; 127: 1184–7.
1. Plunkett A et al. Australas J Dermatol 1998; 39: 225– Griffiths CEM et al. In: Burns T et al., eds. Rook’s textbook of dermatology. 8th ed. UK: Blackwell Publishing Ltd, Bell LM et al. Arch Dermatol 1991; 127: 1184–7.

7. 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: Henseler T et al. J Am Acad Dermatol 1985; 13:450-6.

8. 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– Barker J. Clin Exp Dermatol 2001; 26(4): 321–5.

9. 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)
Additional information1
Other drugs which may act as a trigger for psoriasis include chloroquine, hydroxychloroquine, interferon alfa and the abrupt withdrawal of systemic and potent topical corticosteroids
1. Dermatology Expert Group. Therapeutic guidelines: dermatology. Version 3. Melbourne: Therapeutic Guidelines Limited, 2009.
1. Dermatology Expert Group. Therapeutic guidelines: dermatology. Version 3. Melbourne: Therapeutic Guidelines Limited, 2009.

10. 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.

11. Clinical presentation: classic psoriasis
Well-defined and sharply demarcated
Round/oval-shaped lesions
Usually symmetrical
Erythematous, raised plaques
Covered by white, silvery scales

12. Common sites affected by psoriasis
Can affect any part of the body – typically scalp, elbow, knees and sacrum1
Extent of disease varies
Additional information1
The extent of psoriasis can range from minor inflammation at one or two sites, to total skin involvement with pustulation and constitutional symptoms
1. Dermatology Expert Group. Therapeutic guidelines: dermatology. Version 3. Melbourne: Therapeutic Guidelines Limited, 2009.
1. Menter A et al. Fast facts: psoriasis. 2nd ed. Oxford: Health Press, 2004.

13. Types of psoriasis Chronic plaque Guttate Flexural Erythrodermic
Pustular
Localised and generalised
Local forms
Palmoplantar
Scalp
Nail (psoriatic onychodystrophy)
1. van de Kerkhof P, ed. Textbook of psoriasis. 2nd ed. Melbourne: Blackwell Publishing, Rossi S, ed. Australian medicines handbook. Adelaide: AMH, 2010.

14. Chronic plaque psoriasis
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, Dermatology Expert Group. Therapeutic guidelines: dermatology. Version 3. Melbourne: Therapeutic Guidelines Limited, Weller PA. Psoriasis. In: Marks R, ed. MJA practice essentials – dermatology. 2nd ed. Sydney: Australasian Medical Publishing Company, 2005.

15. Guttate psoriasis 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 infection
1. Dermatology Expert Group. Therapeutic guidelines: dermatology. Version 3. Melbourne: Therapeutic Guidelines Limited, Menter A et al. Fast facts: psoriasis. 2nd ed. Oxford: Health Press, Weller PA. Psoriasis. In: Marks R, ed. MJA practice essentials – dermatology. 2nd ed. Sydney: Australasian Medical Publishing Company, Menter A et al. J Am Acad Dermatol 2008; 58(5): 826–50.

16. Flexural psoriasis 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

17. Erythrodermic psoriasis
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

18. Pustular psoriasis 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

19. Palmoplantar psoriasis1
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.

20. Scalp psoriasis
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, Menter A et al. Fast facts: psoriasis. 2nd ed. Oxford: Health Press, 2004.

21. Nail psoriasis1 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
Additional information1
Pitting
Depressions about 1 mm in diameter on nail surface
May involve only a few fingernails, or may involve the majority of the fingernails
May also involve the toenails, although to a lesser degree
Onycholysis
Produces white to yellow discolouration of distal nail plate
Discolouration may range from 1–2 mm at the distal free edge to involvement of entire nail
‘Oil-drop sign’
Well-demarcated, usually circular colour change
Separate and distinct from onycholysis
1. Menter A et al. Fast facts: psoriasis. 2nd ed. Oxford: Health Press, 2004.
1. Menter A et al. Fast facts: psoriasis. 2nd ed. Oxford: Health Press, 2004.

22. 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

23. 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

24. 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

25. 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

26. 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

27. Alopecia Types: Generalized Localized Male pattern baldness
frontotemporal loss, then midfrontal recession and near vertex
Female pattern baldness
central scalp

28. Alopecia Treatment Minoxidil Treatment of androgen levels
Autografting, etc

29. 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

30. 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

31. 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

32. Latex Allergy Dx: serum test for IgE for latex and via clinical signs
Treatment: avoidance, epinephrine if needed

33. 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

34. Eczema More generic term than used in this textbook
Most common inflammatory skin disease
May be acute, subacute, chronic
Components:
Erythema, scales, vesicles