WCS08 Dermatology 1 Flashcards
Description of lesions
Macule
- circumscribed alteration in ***colour of skin <1 cm
Patch
- circumscribed alteration in ***colour of skin >1 cm
Papule
- circumscribed palpable elevation
- <0.5 cm in diameter
Nodule
- solid mass observed as an elevation / can be palpated
- >0.5 cm in diameter
Plaque
- elevated area of skin
- >=2 cm in diameter
- small plaque sometimes used for such lesions 0.5-2 cm in diameter
Petechiae
- punctate haemorrhagic spot
- 1-2 mm in diameter
Ecchymosis (bruise)
- macular area of haemorrhage
- >2 mm in diameter
Vesicles
- visible accumulations of fluid within / beneath epidermis
- <0.5 cm in diameter (small)
- often grouped
Bullae
- >0.5 cm
- Multilocular (coalesced vesicles in eczema) / Unilocular
Clinical assessment of lesions
Primary:
- Macule —(↑ in size)—> Patch
- Papule
—(↑ in size)—> Plaque
—(↑ in volume)—> Nodule
- Pustule
- Vesicle —(↑ in volume)—> Bulla
- Blister
- Wheal
- Telangiectasia
Secondary:
- Crust
- Scaling
- Fissure
- Erosion
- Ulcer
- Excoriation
- Atrophy
- Lichenification
- Lichenoid
- Necrosis
- Scar
- Exfoliation
Morphology of lesion
- Colour
- white
- brown
- purple (purpuric)
- red (erythematous)
- pink - Shape
- round
- oval
- polygonal
- annular
- umbilicated
- serpiginous (snake-like) - Surface
- Margin
- well
- ill-defined - Pattern
- linear
- annular
- grouped
- dermatomal - Palpate
- Distribution
- generalised
- localised (extensor surfaces, flexural area, body folds, palms, soles, acrofacial)
Palpation of cutaneous lesions
- Soft / Firm / Hard
- Compressible / Non-compressible
- Tender / Non-tender
- Blanchable (e.g. Erythema) / Non-blanchable (e.g. Purpura)
- Rough / Smooth
- Mobile / Fixed to underlying structure
- Dermal / Subcutaneous
- Temperature normal / elevated
- Thrill, Pulsation etc.
History taking in Dermatology (+ SC Medicine)
History of present illness:
1. Onset
2. Site
3. Symptoms
- Itch, Pain, Numb
- Constitutional symptoms: Fatigue, Weakness anorexia, Weight loss, Malaise, Recent acute illness (e.g. URTI, fever, chills), Joint pains
4. Persistent / Transient / Seasonal variation
5. Duration
6. Pattern of spread + Extent of involvement
7. Evolution
8. Provocative factors (heat, cold, sun, exercise, travel history, drug history, pregnancy, season) / Alleviating factors
9. Previous treatment
10. Cosmetic concern
11. Implication to patient’s life (sleep and work)
Past medical history:
1. Hospitalisation
2. Operation
3. Allergies (esp. Drug)
4. Drug / Treatment history
5. Smoking, Drug abuse
6. Atopic history (Asthma, Allergic rhinitis, Atopic dermatitis)
7. Family history of atopy / skin diseases
8. Social history
9. Sexual history
Physical examination in Dermatology
- Distribution
- Neck
- Antecubital fossa
- Popliteal fossa - Associated changes
- psoriasis: nails, naval cavity, scalp, joints - Other sites
- Oral mucosa
- Scalp
- Ears
- Genitalia
SC Medicine:
1. Distribution and arrangement
2. Colour
3. Border
4. Surface features - scaling
5. Palpate
6. Types of lesion - morphology
7. Associated features e.g. hair, nails, genitalia, mucous membrane
***Investigations in Dermatology
- Dermoscopy (magnification with hand lens)
- Woods lamp (365nm)
- Dermatophytosis (green to yellow)
- Erythrasma (coral red) (caused by Corynebacterium minutissimum)
- Porphyria (pinkish red) - Skin patch, Skin prick test
- test for allergens - Laboratory tests
- Gram stain
- Fungal smear
- Scabies scrape
- Skin swab - Skin biopsy
- Histopathology
- IF
- EM
- Culture - Serum serology
Treatment in Dermatology (SC Medicine)
- Topical agents
- Systemic: Oral / IV
- Phototherapy: UVA / UVB
- Laser
- Surgery
- Cryotherapy
- Cauterisation
- Excision
Common dermatoses (skin pathology)
- Urticaria / Hives
- composed of Wheals (Transient edematous papules + plaques)
- pruritic ∵ edema of ***Papillary body - Angioedema
- larger edematous area involving **Dermis + **SC tissue
- deep, ill-defined
—> Both involve same edematous process
—> But at different levels of cutaneous vascular plexus
- Atopic Dermatitis / Eczema
- Contact Dermatitis
- Irritant Dermatitis
- Allergic Contact Dermatitis - Psoriasis
- Psoriasis vulgaris
- Psoriatic erythroderma
- Pustular psoriasis - Impetigo
- Dermatophyte infection / Superficial fungal infection
- Viral warts
- Shingles / Herpes zoster
- Acne vulgaris
- Urticaria
Clinical types
- Acute
- common
- acute onset
- <6 weeks
- ***IgE-dependent with atopy (e.g. triggered by parasites, infections, drugs, alimentary agents)
- can be complement-mediated (e.g. serum-sickness like reaction) - Chronic
- idiopathic mostly
- >6 weeks
- rarely IgE-dependent
Etiology of Urticaria
- Idiopathic (78%)
- Immunological (3%)
- IgE-mediated
- Complement-mediated
- Autoimmune
- Immune contact - Physical (13%)
- Dermographism (i.e. scratching)
- Cold
- Solar
- Cholinergic
- Pressure
- Vibratory - Genetic (1%)
- Distinct angioedema (+ Urticaria) syndromes
- e.g. Hereditary angioedema, Angioedema-urticaria-eosinophilia syndrome - Others
- Vascular / Connective tissue autoimmune disease
- Urticaria due to mast-cell releasing agents, ACE inhibitors
- Non-immune contact urticaria e.g. Exogenous urticants
DDx of Urticaria esp. unresolving, new onset
- Urticarial vasculitis
- Drug eruption
- Viral exanthem
- Bites / Papular urticaria
- Bullous pemphigoid
Treatment of Urticaria
- Discontinue suspected triggers
- ***Anti-histamines: Type 1 (+ 2) histamine receptor antagonists
- ***Prednisone: only for those not controlled on anti-histamines on a short term basis
- Topical steroids: not generally effective
- Atopic Dermatitis / Eczema
Chronic relapsing pruritic exanthematous dermatosis characterised by:
- Allergic diathesis (tendency)
- Erythema
- Oozing
- Crusting
- Excoriations
- Lichenification
- Dehydration of involved skin
Established criteria for diagnosis
1. Hanifin and Rajka’s criteria
2. 1994 UK Working Party’s diagnostic criteria
Distribution of Atopic Dermatitis / Eczema
Age-dependent
- Infant: Extensor surfaces
- Child: Flexures, Trunk
- Adolescent: Neck, Face, Extensor surfaces of upper + lower limbs, Breasts
Morphology:
- **Indistinct border
- **Symmetrical
- **Acute: Erythematous, Exudative, Vesicular, Crusting
- **Chronic: Dry, Scaly, Lichenified, Hyperpigmented
- May be infected
DDx of Atopic Dermatitis
- Seborrhoeic dermatitis
- Contact dermatitis
- Psoriasis
- Scabies
- Genetic / Metabolic disorders
- feat. Atopic eczema with / without raised IgE level
- e.g. Ataxia telangiectasia, Wiscott Aldrich syndrome
- Contact Dermatitis
- Irritant Dermatitis
- inflammatory reaction resulting from exposure to a substance that causes an eruption in most people who come in contact with it - Allergic Contact Dermatitis
- **acquired sensitivity to various substances that produce inflammatory reactions in those and only those who have been **sensitised to the allergen
Patch test
- Intact, uninflammed skin, upper back
- Non-irritating concentration of suspected substances / allergens
- Thin-layer rapid-use epicutaneous (TRUE) test / Finn chambers mounted on tape
- Removed after 48 hours
- Assess for reaction at **48 hours + **96 hours
Look for:
- **Erythematous papules, vesicles, edema
- **Pustules possible with nickel, mercury, potassium iodide
- “Excited skin syndrome”: state of hyper-irritability. Negative test may appear as weakly positive
- Psoriasis
Classification:
1. Psoriasis vulgaris
- **Chronic plaque type
- **Acute guttate type
- Inverse
- Palmoplantar
- ***Psoriatic erythroderma
- ***Pustular psoriasis (嚴重版)
- Pustular psoriasis of von Zumbusch
- Palmoplantar pustulosis
- Acrodermatitis continua
Clinical features of Psoriasis
- Chronic large ***plaque
- Guttate (一點點)
- Pustular
- Erythrodermic (> 90% skin is red)
- ***Nail
- pitting
- onycholysis
- subungual hyperkeratosis
- oil-drop sign
- nail dystrophy - ***Scalp, joints
- **Auspitz sign (punctate bleeding spots when scales scraped off **vs Eczema)
- ***Koebner phenomenon (skin lesions on lines of trauma)
Management of Psoriasis
Choice of therapy depends on:
- Age
- Type
- Site, extent of involvement
- Previous treatments
- Associated medical disorders
- Lifestyle of patients
**Treatment:
1. Topical
- **Emollient
- **Corticosteroid
- **Vitamin D analogue
- **Coal tar
- **Dithranol (aka Anthralin)
- ***Tazarotene (Retinoid)
- ***Phototherapy
- NBUVB, PUVA - ***Systemic treatment
- Methotrexate
- Retinoids
- Cyclosporine -
**Biologics
- **Infliximab (mAb), ***Adalimumab: Successfully treat psoriasis, associated arthritis
- Ustekinumab (human mAb against IL-12, IL-23)
- Secukinumab (human mAb against IL-17A)
- Guselkumab (human mAb against IL-23)
Biologics in treatment of Psoriasis
TNF-α: plays a role in inflammatory process
- **Infliximab (mAb), **Adalimumab: Successfully treat psoriasis, associated arthritis
- Ustekinumab (human mAb against IL-12, IL-23)
- Secukinumab (human mAb against IL-17A)
- Guselkumab (human mAb against IL-23)
- Impetigo
***Staph. aureus / Strept. pyogenes
In skin damaged by previous minor trauma e.g. scratching / insect bite
Clinical features:
- **Vesicles / Pustules that arise on **Erythematous base with ***Crusting formation
DDx:
1. Discoid eczema
2. Herpes simplex
3. Varicella
Management:
Topical / Systemic antibiotics
- Cloxacillin
- Cefuroxime
- Erythromycin
Complication:
- Post-infective glomerulonephritis
- Dermatophyte infection / Superficial fungal infection
- Onychomycosis (Nail)
- Tinea pedis (Feet)
- Tinea cruris (Groin)
- Tinea corporis (Trunk)
- Tinea manuum (Hand)
- Tinea capitis (Scalp)
Management:
- Anti-fungal
- Viral warts
HPV
- transmitted by ***Contact
—> Genital wart: Sexually transmitted
Clinical presentation:
- **Warty lesions with blood vessels beneath surface
- Painful in sole
- Genital wart can be associated with **neoplastic changes e.g. SCC in-situ, SCC
Management:
- **Salicylic acid
- **Cryotherapy
- Cauterisation
- ***Topical 5% Imiquimod
- Shingles / Herpes zoster
- Reactivation of latent varicella-zoster virus
- ***Dermatomal distribution
- Usually elderly
Clinical presentation:
- Presents with **painful erythematous eruption followed by **vesicle and pustule formation that clustered into a ***herpetiform arrangement
- Affect eye if involved CN5
Complications:
- Immune competent patients:
—> Peripheral nerve **palsies
—> **Encephalitis
—> Myelitis
—> Contralateral hemiparesis
Herpes Zoster Ophthalmicus
- reactivation of latent VZV in Trigeminal ganglia (V1, V2)
- ***Hutchinson’s sign (Nasociliary nerve affected —> more likely to have Intraocular inflammation)
Management:
- ***Aciclovir 800mg 5x/day
- Acne vulgaris
- common in teenage (80%)
- ***Male > Female
- positive family history
- often neglected: asymptomatic, not life-threatening
- some patients / parents consider acne to be “normal” for puberty
Pathogenesis:
1. ***Seborrhoea
- Excessive sebum production ∵ over-response to androgen / excessive androgen secretion
- ***Comedogenesis
- Hypercornification of pilosebaceous ducts - Infection
- ***Propionibacterium acnes (P. acnes) - Inflammation
- Lipolysis of sebum of P. acnes
- Superantigen from P. acnes triggers inflammation of comedones
- Inflammatory mediators from ductal corneocytes
Clinical features:
1. Comedones: open / closed
- non-inflamed
- Papules, pustules
- superficial inflamed lesions - Nodules, cysts
- deep inflamed lesions
Management:
1. Topical therapy
- **Retinoids
- **Benzoyl peroxide
- Azelaic acid
- Antibiotics
- Oral therapy
- Antibiotics
- **Isotretinoin (Roaccutane): Stop contraception **1 month after completion of isotretinoin - Photodynamic / Light source therapy
