Skin Diseases & Disorders

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 1. Plunkett A et al. Australas J Dermatol1998; 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 Dermatol1991; 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 Dermatol1998; 39: 225-232. 2. Henseler T et al. J Am AcadDermatol1985; 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: 229–36. 2. 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) 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 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, 2003. 2. 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, 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.

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, 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 AcadDermatol2008; 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, 2009. 2. 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 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