Dermatology Flashcards
Eczema pathophysiology
Atopic dermatitis
Relapsing and remitting
IgE + Eosinophils
Defect in skin barrier
- pH ^
- Protease ^
- Fillagrin ^
Defect in immune system
- IL4, 5, 13 ^
- Th2 mediated response
Eczema aetiology
Atopy
Family history
Smoke exposure
Hygiene hypothesis
Triggers
- House dust mites
- Heat
- Infection
- Stress
- Sweat
- Soaps
Eczema clinical features
Adults - Flexures
Children - Face and extensors
Criteria - Itchy skin + 3 of…
- Dry skin
- Active flexure involvement
- Flexure involvement in past year
- History of atopy
- Onset < 2 years
Other features
- Scaly
- Dry
- Erythematous
- Hyperpigmentation
- Lichenification
Eczema management
Avoid triggers
Emollients
Mild/moderate TCS (Hydrocortisone) ± TCI (Tacrolimus)
Moderate/potent TCS (Betamethasone) ± TCI (Tacrolimus)
Systemic immunosuppressant - Ciclosporin
Phototherapy
Eczema prognosis and complications
Prognostic markers associated with severe disease
- Onset 3-6 months
- Severe disease in childhood
- Atopy
- Small family size
- High serum IgE
Complications
- Infection - Staph A - Topical Fusidic acid
- Psychological
Infection with HSV - Eczema herpeticum
- Emergency
- Give Acyclovir
Contact dermatitis
Irritant - Non-allergic
- Due to weak acids/alkalis - Detergents or cement
- Hands - Erythema
Allergic - Type 4 hypersensitivity
- Head after dye - Acute weeping eczema
- Affects margins of hairline
Topical treatment - Potent steroid - Betamethasone
Psoriasis aetiology
Keratinocyte proliferation
Parakeratosis
Plaque - Most common
- Well demarcated
- Red scaly patches
- Extensor surfaces, sacrum, scalp
- Auspitz sign - Bleeding on scale removal
Flexure
- Older females
- Smooth skin
Seborrhoeic - Nasolabial / Retroauricular
Guttate - Younger patients
- Transient psoriatic rash
- Triggered by Strep P
- Multiple red lesions - “Teardrops”
Pustular
- Palms and soles
- Yellow/brown lesions
Erythrodermic - Total body redness
Psoriasis exacerbating factors
Trauma
Alcohol
Infection
Stress
Drugs
- BB
- ACE-I
- NSAIDs
- Lithium
- Anti-malarial
Psoriasis management
Avoid triggers
Emollients
TCS - Hydrocortisone OD
Topical vitamin D analogue - Calcipotriol OD
No response - Change to BD
Coal tar preparation
Phototherapy
Methotrexate
Ciclosporin
Psoriasis other features and complications
Nails
- Pitting
- Beau lines
- Onycholysis
Arthritis
Psychological
VTE / CVA
Acne vulgaris pathophysiology
Inflammation of pilosebaceous follicle
- Androgen excess - PCOS, puberty, Cushing’s
- Increased sebum production
- Comedone formation
- Comedone infected by propionibacterium acnes
- Inflammation = Acne
Papules
Nodules
Cysts
Acne management
Topical retinoid - Tretinoin
Oral retinoid - Isotretinoin
Benzoyl peroxide
Salicylic acid
Topical abx - Clindamycin
Oral abx - Tetracycline
COCP
Not affected by diet!
Acne complications + Isotretinoin side effects
Psychological
Scarring / Hyperpigmentation
Acne fulminans
- Systemic upset
- Admit
- Responds to oral steroids
Isotretinoin side effects
- Depression
- Dry eyes / skin
- Teratogenic
- Abnormal LFTs
- Hypercholesterolaemia
- Myalgia
Seborrhoeic dermatitis aetiology
Chronic dermatitis
Inflammatory reaction
Proliferation of normal skin inhabitant
Fungus - Malassezia furfur
Associated conditions
- HIV / AIDS
- Parkinson’s
Seborrhoeic dermatitis clinical features
Scaling - Red, itchy, greasy skin
Nasolabial folds Peri-auricular Peri-orbital Scalp - Dandruff Chest Otitis externa Blepharitis
Children - Cradle cap
- Face
- Nappy areas
- Flexors
Seborrhoeic dermatitis management
Scalp - OTC preparations
- Zinc pyrithione - Head & Shoulders
- Tar - Neutrogena T-Gel
Face and body
- Topical Ketoconazole
- Topical corticosteroid
BCC aetiology
Malignant proliferation of epithelial keratinocytes
- Slow growth
- Local invasion
- Metastases are rare
Risk factors
- Sunlight / UV
- Age
- Male
BCC clinical features / investigations / management
Clinical features - Pearly flesh coloured papule
- Telangiectasia
- Ulceration - Central crater
- Sun-exposed sites - Head and neck
Investigations - Biopsy
Management
- Surgical removal
- Curettage
- Cryotherapy
- Topical cream - Imiquimod
- Mohs micrography
SCC aetiology and clinical features
Malignant proliferation of epithelial keratinocytes and skin appendages
Risk factors
- Smoking
- Actinic keratosis - Pre-malignant state
- Bowen’s disease
- Sunlight / UV exposure
- Immunosuppression
Clinical features - Common on the lip in smokers
- Ulceration and bleeding
- Crusty and scaly
- Ill-defined
SCC investigations / management / prognosis
Investigations - Biopsy
SCC in situ - Bowen’s disease
- Cryotherapy
- Topical chemotherapy - Imiquimod
Invasive
< 2cm - Surgical excision
> 2cm - Mohs microscopic surgery
Metastatic - Surgery ± Chemo/Radio
Prognosis - 2-5% metastasise
- Lymph nodes
- Liver
- Brain
- Bone
Malignant melanoma aetiology
Malignant proliferation of melanocytes
UV exposure
Family history
Immunosuppression
Malignant melanoma types
Superficial spreading - Growing mole
- 70% of cases
- Arms, legs, back, chest
- Young people
Nodular - Red or black lump - Bleeds or oozes
- Second most common
- Sun-exposed skin
- Middle aged people
Lentigo maligna - Growing mole
- Less common
- Sun-exposed skin
- Older people
Acral lentiginous - Subungal pigmentation + Hutchinson’s sign
- Rare
- Nails, palms, soles
- African-Americans
- Asians
Malignant melanoma diagnostic features
Major criteria
- Change in size
- Change in shape
- Change in colour
Minor criteria
- Diameter > 7mm
- Inflammation
- Oozing or bleeding
- Altered sensation
Malignant melanoma investigations / management / prognosis / complications
Investigations - ABCDE ± CT staging
- Asymmetry
- Bored
- Colour
- Diameter
- Evolving
Management - Wide local excision ± Chemo/Radio
Prognostic factor - Breslow’s thickness
Complications - Mets
Bullous pemphigoid aetiology and clinical features
Autoimmune
Antibodies against hemidesmosomal proteins
Dermis and epidermis become separated
Clinical features - Itchy tense blisters
- Painless
- Trunk and limb involvement
- Flexures
- Heal without scarring
- No mucosal involvement - Mouth spared
- Nikolsky -ve
Bullous pemphigoid investigations and management
Investigations - Skin biopsy + Immunofluorescence
- IgG and C3 at dermo-epidermal junction
Management
- Oral CS - Pred
- Topical TCI - Tacro
- Topical CS - Clobetasol
- Antihistamine - Hydroxyzine
- Immunosuppressant - Ciclosporin
Pemphigus vulgaris
Autoimmune
Antibodies against desmoglein-3
Separation within epidermis layer
Clinical features - Erythematous blisters
- Painful
- Not itchy
- Mucosal involvement
- Nikolsky +ve
Investigations - Skin biopsy + Immunofluorescence
Management
- Oral CS - Pred
- Immunomodulator - Mycophenolate
Lichen planus aetiology and clinical features
Chronic inflammatory dermatosis
Most likely AI
Keratinocyte apoptosis
Clinical features - All the P’s
- Pruritus
- Purple
- Papule
- Polygonal + White lines = Wickham’s striae
- Plaque
- Palms, soles, genetalia, flexor surfaces
Koebner phenomenon - New lesions at site of trauma
Oral involvement - White lace pattern
Lichen planus drug eruptions / management
Gold
Quinine
Thiazides
Topical CS - Clobetasol
Oral CS - Pred
Antihistamine - Chlorphenamine
Acne rosacea
Risk factors / triggers
- Fair skin
- Extreme temperatures - Hot baths / showers
- Sunlight
- Emotional stress
- Hot drinks
- Alcohol
Clinical features
- Facial flushing - Cheeks, nose, forehead
- Telangiectasia
- Later develops into persistent erythema + Papules / pustules
- Rhinophyma
- Orbital blepharitis
Management
- Topical abx - Met
- Oral abx - Doxy
- Telangiectasia - Laser therapy
- Avoid triggers - Daily sunscreen
Cellulitis aetiology and clinical features
Acute infection of skin an subcutaneous tissue
Staph A
Strep pyogenes
Risk factors
- Immunocompromise
- Poor healing - Diet, smoking, DM
Clinical features - Red, hot, painful, swollen
- Systemic upset - Fever?
Orbital features
- Ophthalmoplegia
- Exophthalmos
- Painful movements
- Visual disturbances
Cellulitis investigations / classification / management / complications
Investigations - Clinical diagnosis
- Swab area
- Septic screen?
- D-dimer - Rule out DVT?
Eron classification
- No systemic upset + No uncontrolled comorbs
- No systemic upset + Comorbs
- Systemic upset + Unstable comorbs
- Sepsis + Severe infection (E.g. nec fasc)
Management - Fluclox
Complications
- Sepsis
- Osteomyelitis
Scabies aetiology and clinical features
Mite - Sarcoptes scabiei
Transmission
- Prolonged skin contact
- Bedsheets
Children and young adults
Widespread pruritus - Worse at night
- Abdomen
- Forearms
- Hands - Between fingers
Linear burrows
- Interdigital webs
- Flexor aspect of wrist
Scabies investigations / management
Clinical diagnosis
Permethrin x2
Wash all clothes and bedding
Treat all household contacts
Pruritus may last 4-6 weeks post-eradication
Molluscum contagiosum
Viral
- Close contact
- Shared towels
Clinical features - Children ± Atopic eczema
- Smooth pearly white papule
- Central dimple
- Up to 5mm
- Everywhere except palms and soles
- Extremely itchy
Management - Self-limiting
- Squeeze after a bath
Impetigo
Staph aureus - Incubation period 4-10 days
- Direct contact
- Toys / equipment
- Clothing
Clinical features - Gold crusted lesions
- Face and mouth
- Flexures
- Limbs
Investigations - Swab ± MC&S
Management
- Topical hydrogen peroxide
- Topical abx - Fusidic acid
- Oral abx - Fluclox
- School exclusion - 48 hours after treatment initiated
Scalded skin syndrome
Staph A - Epidermidis toxin
Clinical features
- Red painful skin
- Nikolsky sign +ve
Management - IV fluids
+ Fluclox
Necrotising fasciitis aetiology
- Mixed anaerobes and aerobes
- Most common
- Occurs post-surgery in DM - Strep pyogenes
Risk factors
- DM - SGLT-2 inhibitors
- VZV
- Surgery / Trauma - Abdo surgery
- Non-traumatic skin lesions
- IVDU
- Immunsuppression
Necrotising fasciitis clinical features / management / prognosis
Perineum most commonly affected - Fournier’s gangrene
Severe pain - Out of keeping with wound size/appearance
Haemorrhagic bullae
Subcutaneous emphysema
Signs of sepsis - Fever, tachy, etc.
Management
- Surgical debridement
- IV broad spec abx - Vanc + Taz
Prognosis - Mortality is 20%
Seborrhoeic keratosis
Benign epidermal skin lesions
Clinical features - Elderly + UV exposure
- Light brown/black
- Stuck-on appearance
- Keratotic plugs on surface
Management
- Reassurance
- Cryotherapy/curettage if bothersome
Erythema nodosum
Inflammation of subcutaneous fat
Hypersensitivity reaction
Aetiology - NODOSUM
- No - Idiopathic
- Drugs - Penicillin / Sulphonamides
- OCP / Pregnancy
- Sarcoidosis / TB
- UC / Crohn’s
- Microbiology - Strep
Clinical features - Shins!
- Painful red lesions
- Heal without scarring
Management - Treat cause
- Resolve within 6 weeks
Pyoderma gangrenosum
Aetiology
- UC / Crohn’s
- RA / SLE
- Lymphoma / Leukaemia
- PBC
Clinical features
- Lower limb
- Small red papule
- Becomes ulcerated
- Systemic symptoms - Fever?
Management
- Oral CS - Pred
- Immunosuppressant - Ciclosporin
Erythroderma
Any rash > 95% skin coverage
Aetiology
- Eczema
- Psoriasis
- Drugs - Gold
- Lymphoma
- Leukaemia
Management - IV fluids
- Wet wraps and emollients
- Treat cause
Complications
- High output cardiac failure
- Electrolyte imbalance
- Dehydration
- Hypothermia
- Hypoglycaemia
Erythema multiforme
Type 4 hypersensitivity
Aetiology - Triggered by infection - HSV
Clinical features
- Target lesions
- Backs of hands and feet - Spreads to torso
- Upper limbs more commonly affected
- Haemorrhagic lips
Management - Treat cause
Venous ulcers aetiology
Incompetent valves + Chronic venous insufficiency
Stasis of blood flow - Blood flows into superficial veins
= Oedema + Eczema + Varicose veins
Age
Smoking
Family history
Orthostatic compression
Venous ulcers clinical features
Lateral and medial malleolus - Posterior calf Edge - Shallow, sloping, irregular Base - Slough, granulation, moist Painless Bleeding
Venous ulcers investigations and management
ABPI - Assess for poor arterial flow - Could affect wound healing
Swab + MC&S
HbA1c
Management
- Debridement ± Abx (Fluclox)
- Compression bandaging - 4 layers
- Pentoxifylline
Arterial ulcers aetiology and clinical features
CVD
PAD
Smoking
DM
Presentation - Dorsal foot, toe, heel
- Punched out
- Well demarcated
- Base - Grey granulation
- Painful
- Do not bleed on probing
- Cold with no palpable pulses
Arterial ulcers investigations and management
Pedal pulses
ABPI < 0.8
Colour doppler ± Angiography
Management
- Smoking cessation
- Revascularisation surgery
CV risk management
- Statin
- ACE-I
- Aspirin
- Clopidogrel
Neuropathic ulcers
Aetiology - Pressure
Clinical features
- Plantar surface of hallux and MTPJ
- Punched out and deep
- Bleeds on probing
- Painless
- Absent local sensation
Management - Cushioned shoes to reduce callous formation
