Transcript L6_Skin Diseases

Skin Diseases & Disorders
Skin Anatomy







Stratum corneum
Stratum germinativum
Keratin
Melanin
Sebaceous glands
Sudoriferous glands
Hair follicles
Structure of the skin
Skin Lesions
Flat: macules
Elevated:
Solid: papules, nodules, wheals,
tumors
Liquid-filled: vesicles, bullae, pustules,
cysts
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.
5
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





Well-defined and
sharply demarcated
Round/oval-shaped
lesions
Usually symmetrical
Erythematous, raised
plaques
Covered by white,
silvery scales
11
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.
12
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.
13
Chronic plaque psoriasis





Most common type –
affects approximately
85%1
Features pink, welldefined 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.
14
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 Acad Dermatol 2008; 58(5): 826–50.
15
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
16
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
17
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
18
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.
19
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.
20
Nail psoriasis1






May be present in
patients with any
type of psoriasis
Can take
several forms:
Pitting: discrete, wellcircumscribed 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.
21
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:
Generalized
Localized
Male pattern baldness
frontotemporal loss, then midfrontal
recession and near vertex
Female 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