Dermatology Flashcards
What is a vesicle?
Fluid-filled blister less than 0.5 cm in diameter
What is a bulla?
Fluid-filled blister more than 0.5 cm in diameter
What is a skin fissure?
Deep crack/crevice into skin
What is a macule?
Flat pigmented lesion less than 1 cm in diameter
What is a patch?
Flat pigmented lesion more than 1 cm in diamter
What is a papule?
Raised lesion less than 0.5 cm in diameter
What is a nodule?
Raised lesion more than 0.5 cm in diameter
What is a pustule?
Pus-filled lesion
What is a plaque?
Raised lesion more than 1 cm in diameter
What is lichenification?
Thickened skin
What is purpura?
Purple pigmentation that does not blanche
What is petechiae?
1-2 mm of purpura
What is erythema?
Red pigmentation that does blanche
What is an erosion?
Superficial break in epidermis
What is an ulcer?
Deep break in epidermis and dermis
What is a wheal?
Compressible dermal swelling
List skin manifestations of diabetes
Flexural candidiasis Folliculitis, infection Necrobiosis lipoidica Acanthosis nigricans Ulcers Xanthomata
What is necrobiosis lipoidica?
Waxy, shiny red-brown plaques with atrophic yellow lesions on shins
What is acanthosis nigricans?
Velvety thickening of skin, usually in the axillae
What is the main skin manifestation of Coeliac disease?
Dermatitis herpetiformis
List skin manifestations of inflammatory bowel disease
Erythema nodosum
Pyoderma gangrenosum
What is erythema nodosum?
Tender, ill-defined nodules usually found on shins
What is pyoderma gangrenosum?
Recurring nodulo-pustular ulcers that have a red-blue necrotic edge
List skin manifestations of systemic lupus erythematosus
Butterfly rash
Photosensitivity
Alopecia
What is the main skin manifestation of herpes simplex infection?
Erythema multiforme
List skin manifestations of vasculitis
Purpura (may be palpable)
Nodules
Livedo reticularis
What is livedo reticularis?
Mottled red-blue lesions that don’t blanche
Usually triggered in the cold
List skin manifestations of dermatomyositis
Heliotrope rash
Gottron’s papules
Scaly red plaques over neck (V-sign)
Periungual redness
List aetiology/risk factors for atopic dermatitis
Genetic mutation in filaggrin gene
Overactive TH2 cells results in more circulating IL-4, IL-5, IgE
Infection (Staph aureus)
Exacerbators (dust, temperature, allergies)
List clinical features of atopic dermatitis
Itchy, dry skin Flexural scale and erythema Weepy vesicles Lichenification Hyperlinear pals Eczema herpeticum (HSV infection)
What investigations would you do for atopic dermatitis?
Serum IgE
What is the clinical criteria for diagnosing childhood eczema?
Itch + 3 of: Flexural rash Onset before 2 years of age History of atopy Dry skin
Outline treatment options for atopic dermatitis
Allergen/trigger avoidance
Emollients (Epaderm, Diprobase)
Topical steroid (hydrocortisone, clobetasone, betametasone, mometasone, clobetasol)
Immunomodulator (tacrolimus, ciclosporin)
Antibiotic if infection
Antihistamine
Paste bandaging
Phototherapy/systemic therapy if non-responsive
Ointments are more effective than emollients for dry skin. True/False?
True
What is contact allergic dermatitis?
Type IV hypersensitivity skin reaction to environmental allergens
List aetiology/risk factors for contact allergic dermatitis
Nickel
Chemicals, creams
Rubber
Occupational substances
List clinical features of contact allergic dermatitis
Localised rash with cut-off patern
Itch
Rhinitis
Wheal
What is contact irritant dermatitis?
Non-specific skin reaction to environmental substances
List aetiology/risk factors for contact irritant dermatitis
Soap, detergents Oil Bleach Trauma Occupational substances
List clinical features of contact irritant dermatitis
Localised rash/redness
Weeping
Dry fissures
Usually hands affected
How would you differentiate between contact allergic and irritant dermatitis?
Patch testing to check for allergic trigger
Outline treatment for contact dermatitis
Avoid allergen/trigger
Topical steroid
What is stasis dermatitis?
Chronic venous insufficiency/hypertension causes blood pooling and skin disease
List aetiology/risk factors for stasis dermatitis
Obesity
Varicose veins
History of DVT
List clinical features of stasis dermatitis
Haemosiderin staining (brown pigments)
Ulcers
Hair loss
Painless scale, itch
Outline treatment for stasis dermatitis
Emollients
Topical steroid
Compression stockings, leg elevation
What is lichen simplex dermatitis?
Self-induced eczema due to repeated physical trauma
What is acne vulgaris?
Inflammation of pilosebaceous unit that causes a rash, typically in areas high in concentration of these glands (face, neck, chest, back)
What causes comedones in acne?
Abnormal keratinisation/desquamation within pilosebaceous unit causes blockage of secretions and comedone formation
Open comedones are white/black heads and closed comedones are white/black heads
Open comedones are blackheads and closed comedones are whiteheads
List aetiology/risk factors for acne vulgaris
Increased sebum production (increased androgens, CRH)
P. acnes infection
Occlusion of pilosebaceous unit
Dermal inflammation
List clinical features of acne
Comedones
Seborrhoea
Inflammatory papules and pustules, nodules
Scars and cysts in severe acne
Psych disturbance
Develop keloid scars: thick inflamed lesions on trunk and shoulders
Outline treatment for mild, moderate and severe acne
Education and psych support, dispel myths
Mild: topical benzoyl peroxide +/- azelaic acid, antibiotic
Moderate: topical doxycycline/erythromycin + benzoyl peroxide
Severe: oral isotretinoin
What is acne rosacea?
Chronic relapsing-remitting facial rash usually affecting convex areas
List aetiology/risk factors for acne rosacea
Largely unknown Chlamydia Demodex mite Spicy food Alcohol
List clinical features of acne rosacea
Rhinophyma Facial flushing NO COMEDONES Telangiectasia Erythema
Outline treatment of acne rosacea
Avoid irritants
Topical azelaic acid + metronidazole
Oral azithromycin for chlamydia
What is pemphigus vulgaris?
Autoimmune blistering condition caused by IgG produced against desmoglein 3, causing loss of adhesion of epidermis to basal layer
List aetiology/risk factors for pemphigus vulgaris
Autoimmunity
Genetics
Drugs (ACEi, NSAID, phenobarbitol, levodopa)
List clinical features of pemphigus vulgaris
Flaccid, superficial, fluid-filled blisters
Rupture leaves erosions
Nikolsky sign +ve
Oral mucosal ulcers
What investigation would you do for pemphigus vulgaris?
Skin biopsy for immunofluorescence shows IgG crazy-paving/chicken-wire pattern in epidermis
Outline treatment for pemphigus vulgaris
High-dose oral prednisolone
Immunosuppression (rituximab, azathioprine)
What is bullous pemphigoid?
Autoimmune blistering condition caused by IgG produced against hemidesmosomes and basement membrane, causing sub-epidermal separation
Which is more common - bullous pemphigoid or pemphigus vulgaris?
Bullous pemphigoid
List clinical features of bullous pemphigoid
Large, tense bullae
Urticated base
Nikolsky sign -ve
What investigation would you do for bullous pemphigoid?
Skin biopsy for immunofluorescence shows linear IgG deposition along basement membrane
Outline treatment for bullous pemphigoid
High-dose oral steroid
Clobetasol propionate cream
What is dermatitis herpetiformis?
Rare autoimmune blistering condition caused by IgA cross-reacting with connective tissue matrix proteins, causing sub-epidermal separation
Which condition is associated with dermatitis herpetiformis?
Coeliac disease (HLA DQ2)
List clinical features of dermatitis herpetiformis
Small, intense itchy blisters usually on elbow/scalp/shoulders/ankles
Crusting
What investigation would you do for dermatitis herpetiformis?
Skin biopsy histology shows dermal papillary microabscesses
IgA immunofluorescence
Outline treatment for dermatitis herpetiformis
Oral dapsone
Gluten-free diet
List skin manifestations of hyperthyroidism
Moist smooth skin Facial flushing Palmar erythema Fine, thin hair/alopecia Hyperhidrosis Nail changes Hyperpigmentation Pretibial myxoedema Urticaria
List skin manifestations of hypothyroidism
Cold, dry, pale skin Coarse, brittle hair Thickened nails Generalised myxoedema Peri-orbital oedema Facial puffiness
List skin manifestations of Addison’s disease
Palmar crease pigmentation
Buccal pigmentation
List skin manifestations of endocrine tumours
Hyperpigmentation
Hirsutism
Acne
Baldness
List skin manifestations of systemic sclerosis
Pinched mouth Radial furrows Beaked nose Facial telangiectasia Raynaud's phenomenon Dysphagia Sclerodactyly Calcinosis
What is pityriasis rosea?
Common skin rash tending to occur in epidemics, presenting with solitary herald patch with subsequent truncal eruption of pink oval lesions with scale
What is vitiligo?
Acquired de-pigmentation caused by loss of melanocytes
List aetiology/risk factors for generalised hair loss
Telogen effluvium Endocrine disease (thyroid) Drugs Dietary deficiency (iron, zinc, vit D) Alopecia areata Malnutrition
What investigations would you do for hair loss?
Skin scraping, hair plucking Woods lamp examination Dermoscopy Scalp biopsy Bloods: hormones, FBC, thyroid
What is alopecia areata?
Autoimmune cause of hair loss in round/spotty distribution all over the body
What is hirsutism?
Male-pattern hair growth in response to increased androgenic drive/levels
List aetiology/risk factors of hirsutism
Familial, genetics Adrenal hyperplasia/tumour PCOS Hyperprolactinaemia Drugs (danazol, glucocorticoids)
What investigations would you do for hirsutism?
Hormones: testosterone, DHEA, SHBG, LH, FSH
Ovarian USS if indicated
What is hypertrichosis?
Excessive hair growth in a non-androgenic distribution
List aetiology/risk factors for hypertrichosis
Naevi Chronic scarring/inflammation Malnutrition Anorexia Porphyria cutanea tarda Occult malignancy Drugs (minoxidil, phenytoin, ciclosporin)
What is the most common type of drug skin eruption?
Maculopapular/Exanthematous - up to 2-3 weeks after administration
List some drugs that cause exanthematous skin eruptions
Penicillin Carbamazepine Allopurinol NSAID Cephalosporins
When does drug-induced urticaria usually onset?
Within 36 hours of administration but may develop within minutes when re-challenged
What is Steven-Johnson syndrome?
Full-thickness epidermal necrolysis, involving mucosal erosions, occurring in response to drugs and/or illness
List some drugs that cause Steven-Johnson syndrome
Allopurinol
Antibiotics
Anticonvulsants
NSAID
What is the difference between Steven-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN)?
SJS involves up to 30% epidermal detachment
TEN involves more than 30% epidermal detachment
List some drugs that cause erythroderma/exfoliative dermatitis
Barbiturates Gold Quinine Sulphonamides Carbamazepine Allopurinol
Fixed drug eruptions are mediated by what cells and occur when?
Mediated by T memory cells
Occur 1-2 weeks after exposure and may persist and reappear with further exposure
List some drugs that cause fixed drug eruptions
Tetracyclines Phenolphthalein NSAIDs Quinine Oral contraceptive
List some drugs that cause lichenoid eruptions
B blockers
Captopril
Thiazides
Furosemide
Outline general management of drug eruptions
Stop likely drug offender Regular emollients for dryness and itch Topical steroid IV hydrocortisone + antihistamine for urticaria Specialist/ICU management if severe
Outline management of an insect bite
Prevent with insect repellant
Topical steroid
Antihistamine
Treat affected animals and environment
What disease can tick bites cause and why?
Lyme disease
Ticks transmit Borrelia Burgdorferi, a spirochaete responsible for lyme disease
Describe the first clinical stage of lyme disease
Erythema chronicum migrans, usually up to 14 days after bite, seen as a solitary macule or annular lesion
May have mild systemic symptoms
Describe the second clinical stage of lyme disease
Borrelia lymphocytoma occurs up to 6 months after the bite, involving firm blue-red swelling or earlobes/nipples
Tender local lymphadenopathy
Associated numbness/arthralgia/myalgia/paralysis
Describe the third clinical stage of lyme disease
Acrodermatitis chronica atrophicans up to 8 years after initial infection, involving blue-red discolouration and atrophy
Early inflammation, late atrophy
Associated arthritis/neuropathy/pain
List non-cutaneous features of lyme disease
Fever, malaise, lymphadenopathy Cough Headache Conjunctivitis, keratitis, iritis Meningitis, encephalitis, GBS Heart block, arrhythmia, cardiomyopathy Arthralgia, tendonitis Orchitis, proteinuria, haematuria
Outline treatment of lyme disease
Doxycycline + amoxicillin/cefuoroxime/erythromycin
IV penicillin/ceftriaxone if severe
What systemic reaction may be caused in treating lyme disease in the 1st 24 hours?
Jarisch Herxheimer reaction involving release of endotoxin due to large numbers of organisms being killed
What is scabies?
Contagious skin infestation caused by Sarcoptes scabei
List aetiology/risk factors for scabies
Poor hygiene
Prolonged close/sexual contact
Hotel bedding
When do symptoms of scabies typically onset?
Individuals can be asymptomatic for up to 6 weeks, then delayed hypersensitivity reaction develops
List clinical features of scabies
Intensely itchy Red papules Rubbery nodules Burrow lines Vesicles, pustules Involves finger webs, wrist flexures, axillae, abdomen, palms, soles
How would you make the diagnosis of scabies?
Clinical diagnosis
Skin scraping and microscopy
Outline treatment of scabies
Permethrin cream Symptom relief (steroid, anti-pruritic)
What are headlice?
Tiny flightless insects that feed on blood from the scalp
Infestation common in school children
List clinical features of headlice
Eggs in scalp hair
Itch
Papular rash on nape of neck
Secondary infection
Outline treatment of headlice
Physical removal using fine-tooth comb and shampoo
Anti-parasitic (malathion, dimeticone)
What is furunculosis?
Acute deep infection of hair follicles
What is staphylococcal scalded skin syndrome?
Epidermolytic exotoxin produced by Staph that causes splitting between desmosomes in granular layer
What are the three phases in the growth cycle of a hair?
Anagen (growth)
Catagen (involution)
Telogen (rest)
Most hair is in the anagen phase. True/False?
True
What is telogen effluvium?
Reversible/transient hair loss due to stress
What treatment may be tried for androgenetic hair loss?
Minoxidil
Anti-androgenic drugs
What is Beau’s line?
White horizontal line on nail caused by transient arrest in nail growth due to stress/trauma/illness
What are main causes of acute paronychia? (inflammation of the nail)
Staph or Strep infection
What are the main causes of chronic paronychia?
Candida
Mould
What are characteristic histological features of acute eczema?
Spongiosis
Acanthosis
Inflammatory infiltrate
List the main endogenous dermatitis conditions
Atopic dermatitis Seborrhoeic dermatitis Discoid eczema Nodular prurigo Lichen simplex chronicus
What is impetigo?
Highly contagious infection mostly seen in children caused by Staph aureus
List clinical features of impetigo
Well-defined honey-coloured crusting on face/nose
Erythematous base
Superficial flaccid blisters
Weeping
Outline treatment for impetigo
Topical fusidic acid
Oral flucloxacillin
Avoid school/close contact
What is erysipelas?
Localised cellulitis usually affecting the face caused by Strep pyogenes
List clinical features of erysipelas
Sharply defined superficial rash, usually on face
Unilateral
Associated fever
Which antibiotic is used to treat erysipelas?
Penicillin
What is cellulitis?
Acute severe infection of skin and soft tissues that is deeper and less well-defined than erysipelas
List aetiology/risk factors for cellulitis
B-haemolytic Strep (pyogenes) Staph aureus Trauma Vascular disease, poor healing Immunosuppression
List clinical features of cellulitis
Severe pain Swelling Erythema Systemic upset Lymphadenopathy
Outline treatment of cellulitis
IV benzylpenicillin + PO flucloxacillin
Erythromycin if penicillin-allergic
What is necrotising fasciitis?
Life-threatening subcutaneous/soft tissue infection
List aetiology/risk factors for necrotising fasciitis
Type 1: polymicrobial (mixed aerobes-anaerobes)
Type 2: group A Strep (pyogenes)
List clinical features of necrotising fasciitis
Extreme pain Paraesthesia Systemic upset SEPSIS Spreading erythema
Outline treatment of necrotising fasciitis
Surgical debridement
IV benzylpenicillin + clindamycin
Which strain of HPV causes viral warts?
HPV 6 and 11
List clinical features of viral warts
Skin-coloured/brown lesions Affect large confluence areas on soles Highly infectious May affect genitals Koebner phenomenon
Outline treatment of viral warts
Resolve spontaneously Topical keratolytic (salicyclic acid) Liquid nitrogen cryotherapy Cautery/laser therapy Imiquimod Antiviral if severe
List aetiology/risk factors for herpes infection
Triggers (sunlight, fever)
Immunosuppression
Close contact with infected person
List clinical features of herpes infection
Burning
Itching
Grouped, painful vesicles
Erythematous base
Outline treatment of herpes
Self-limiting
Topical aciclovir
What is shingles?
Reactivation of Varicella zoster in dorsal root ganglion of spine causes skin rash in unilateral dermatomal distribution
List clinical features of shingles
Polymorphic eruption Red papules, vesicles, pustules, crusting Dermatomal distribution May heal with scarring Post-herpetic neuralgia
Outline treatment of shingles
Analgesia
Oral aciclovir
What is molluscum contagiosum?
Pox virus causes chronic infection usually in children
List clinical features of molluscum contagiosum
Pink papules with central puntum
Expressed white discharge
Painless nodules
Outline treatment of molluscum contagiosum
Self-resolving
Cryotherapy
Curettage
What are dermatophyte infections?
Fungal infections caused by ringworm organisms (Epidermophyton, Trichophyton, Microsporum)
List clinical features of dermatophyte infections
Round, itchy lesions with inflamed border
Tinea corporis/cruris/pedis/capitis/unguium
Well-demarcated red plaques
Between toe clefts
Whitening of nails
Scale
Alopecia
How would you investigate fungal skin infections?
Skin scraping microscopy/culture
Wood’s lamp fluoresecence
Outline treatment for fungal skin infections
Antifungal cream (terbinafine, clotrimazole) Oral terbinafine for scalp involvement
List aetiology/risk factors for Candida infection
Immunosuppression
Long-term steroid/inhaler use
Poor hygiene
List clinical features of Candida infection
Pink, moist “satellite” lesions
Peeling
Pustules, papules
Oral white patches
Outline treatment of Candida infection
Topical clotrimzaole/terbinafine Oral nystatin Vaginal imidazole Steroid cream if itchy/finalmed Oral fluconazole if not improving
List clinical features of lichen planus
Purple pruritic polyangular planar papules Usually on flexor aspects White lacy markings (Wickham's striae) Scarring alopecia Longitudinal ridges, pterygium on nails Oral/genital lesions
Outline treatment of lichen planus
Topical steroid
Antifungal (topical, spray)
What is a hemangioma?
Benign vascular dilation typically in neonates
List clinical features of hemangioma
Strawberry naevus: rapidly enlarging red spot
Pyogenic granuloma: moist red lesion on finger that bleeds easily
Outline treatment for hemangioma
Self-resolving
Curettage
B-blocker
Steroid
List the main non-melanoma skin cancers
Actinic keratosis
Bowen’s disease
Basal cell carcinoma
Squamous cell carcinoma
What is actinic keratosis?
Pre-malignant partial thickness dysplasia involving intra-epidermal porliferation of atypical keratinocytes
List aetiology/risk factors for actinic keratosis
Sun damage
Fair skin
List clinical features of actinic keratosis
Erythematous crumbly yellow-white scale
Crusts
Tense skin
Actinic lentinges
Outline treatment for actinic keratosis
Education, sun protection
Cryotherapy
Surgical excision/curettage if suspect SCC
Topical 5-fluoracil/imiquimod/diclofenac
What is bowen’s disease?
Pre-malignant full thickness dysplasia (carcinoma in-situ)
List clinical features of bowen’s disease
Slow-growing red scaly plaque
Erythema
Ill-defined
Usually on lower legs of females
Outline treatment of bowen’s disease
Cryotherapy
Topical 5-fluoracil/imiquimod
Photodynamic therapy
What is the most common skin cancer?
Basal cell carcinoma
List aetiology/risk factors for basal cell carcinoma
Sun exposure
Mutated TP53 gene
PTCH1 mutation causes Gorlin’s syndrome
List clinical features of basal cell carcinoma
Slow-growing pearly translucent lump with rolled telangiectatic edge
Well-define
May have central ulceration
Outline treatment of basal cell carcinoma
Excision Mohs' surgery if recurrent/difficult Photodynamic therapy Radiotherapy if big Cryotherapy/curettage Imiquimod
List aetiology/risk factors for squamous cell carcinoma
Sun exposure Actinic keratosis Bowen's disease Marjolin's ulcer Smoking Chronic inflammation
List clinical features of squamous cell carcinoma
Ulcerating, hyperkeratotic lesion
Firm and irregular
Ill-defined
Crusted
Outline treatment of squamous cell carcinoma
Excision
Topical imiquimod/5-fluoracil
Radiotherapy
What is basal cell papilloma?
Common benign lesion involving overgrowth of basal cell layer
AKA seborrhoeic keratosis
List aetiology/risk factors for basal cell papilloma
Chronic UV damage
Genetics
Idiopathic
FGR3 mutation
List clinical features of basal cell papilloma
Brown greasy “stuck-on” appearance
Irritating, catch on clothes etc.
Outline treatment of basal cell papiloma
Leave if asymptomatic
Cryotherapy/curettage
Excision
What are lentigos?
Brown macules/papules that may be pre-malignant
What is lentigo maligna?
Precursor to invasive melanoma
melanoma in-situ
What are melanocytic naevi?
Benign overgrowth of melanocytes that are mostly not pre-malignant
What are the different histological types of melanocytic naevi?
Junctional: at DEJ
Compound: into dermis from DEJ
Intradermal: in dermis
List aetiology/risk factors for melanocytic naevi
Congenital “birthmark”
Idiopathic
Sun/UV exposure
When would you be worried about a melanocytic naevus?
If greater than 5-6mm and irregular and growing
What is the fastest increasing skin cancer?
Malignant melanoma
List aetiology/risk factors for malignant melanoma
Sun/UV exposure Sunburn Sunbed use Sun, sun, suuuuun, all over our bodies Fair skin type More than 50 melanocytic naevi Lentigo maligna Family history BRAF gene mutation
What are the different histological types of melanoma?
Superficial spreading (most common)
Lentigo maligna
Acral lentiginous
Nodular
List clinical features of melanoma
Rapidly growing/evolving irregular lesion Varied pigmentation, generally brown Associated ulceration Asymmetry Diameter greater than 6mm
Outline treatment of melanoma
Excision
Sentinel node biopsy
Chemotherapy
Education and protection from sun
Define a chronic leg ulcers
Open lesion between knee and ankle joint that remains unhealed for 4 weeks
List aetiology/risk factors for leg ulcers
Venous/arterial insufficiency Diabetes DVT Malignancy Vasculitis Inflammation Obesity
List clinical features of venous ulcers
Superficial Venous disease (varicose veins) Haemosiderin staining Venous eczema Lipidodermatosclerosis Atrophie blanche Generally painless
List clinical features of arterial ulcers
Deep, punched out Tendon exposure Foot/toes/pressure points Hair loss Cold limb Generally painful
What measurement is essential to make before applying pressure bandaging?
ABPI
State the cut-offs for ABPI
0.8 - 1.3 is normal
Less than 0.8 indicates vascular disease
Greater than 1.5 indicates calcificiation
Outline treatment of venous ulcers
De-slough agent Graduated compression greater at ankle than below knee Non-adherent dressing Weekly/daily changing Aim to heal by 12 weeks Emollients/steroid for eczema
Outline treatment of arterial ulcers
Pain relief Lifestyle changes Aspirin Treat infection Soffban, crepe bandage toe to knee to reduce oedema Vascular surgery Topical -ve pressure treatment
What are port-wine stains?
Naevus flammeus
Capillary malformation results in macular lesion that is lifelong and usually unilateral
Do not extend but may get hyperplasia
What is the commonest genodermatosis?
Neurofibromatosis type 1
What is neurofibromatosis type 1?
Autosomal dominant defect in NF1 amino acid which inactivates oncogenes, causing neuroectodermal disorder
List clinical features of neurofibromatosis
Cafe au lait macules Axillary freckles Lisch nodules in iris Learning difficulty Skeletal dysplasia Fleshy skin tags/neurofibromas
What is tuberous sclerosis?
Autosomal dominant defect in TSC1 (hamartin) or TSC2 (tuberin) that allows hamartoma development
List clinical features of tuberous sclerosis
Ash leaf (depigmented) macules Dental pits Periungual fibromata Adenoma sebaceum Shagreen patch Epilepsy Mental retardation Autism Lipoma
Outline treatment for neurofibromatosis type 1 and tuberous sclerosis
Surgical removal of skin lesions
Laser therapy
Surveillance
Treat symptoms/complications
What is epidermolysis bullosa?
Inherited skin fragility involving mutated skin structure proteins
What are the histological subtypes of epidermolysis bulosa?
Simplex: involves epidermis
Junctional: involves DEJ
Dystrophic: involves dermis
List clinical features of epidermolysis bullosa
Recurrent blisters and erosions Poor healing Milia Scarring Dystrophic nails
Outline treatment of epidermolysis bullosa
Dressing wounds
Topical antibacterial
Sterile drainage
List hazards of UV exposure
Sunburn
Eye damage
Skin cancer
Photosensitivity
Sort the different types of UV radiation from longest to shortest wavelength (most penetrating to least penetrating)
UVA
UVB
UVC
What are the main forms of therapeutic UV radiation?
Phototherapy (UVB)
Photochemotherapy (Psoralen UVA) (PUVA)
Photodynamic therapy
List Fitzpatrick skin types
I: always burns II: usually burns, can tan III: usually tans, can burn IV: always tans V: brown skin VI: black skin
When does UVB “sunburn” erythema onset? What mediates the erythema?
Onset 2-4 hours
Peak 12-24 hours
Mediated by prostaglandins
When does PUVA erythema onset? What mediates the erythema?
Onset 24 hours
Peak 96 hours
Mediated by oxygen/free radicals
It is more likely to develop squamous cell carcinoma with cumulative sunburn and melanoma with acute sunburn. True/False?
True
List the main immunological photodermatoses
Polymorphic light eruption Actinic prurigo Solar urticaria Chronic actinic dermatitis Hydro vacciniforme
What is polymorphic light eruption?
Delayed reaction to sunlight involving non-scarring papulo-vesicular rash and hardening of skin
When does actinic prurigo typically onset?
Childhood
What is solar urticaria?
Rare acute type 1 hypersensitivity reaction to sunlight
List the main genetic photodermatose
Xeroderma pigmentosum
What is xeroderma pigmentosum?
Rare, autosomal recessive failure of DNA repair, causing rapid photo-ageing of skin and skin cancer
Often death in teens
List common drugs that cause photosensitivity
Psoralens (lime, celery) Antibiotics (sulfonamides, tetracycline, fluoroquinolones) Diuretics NSAIDs Quinine Amiodarone
What are porphyrias?
Inherited/acquired photosensitivty caused by deficit in enzymes in the haem pathway, resulting in build-up of porphyrins that react to light
Which enzyme is deficient in porphyria cutanea tarda?
Uroporphyrinogen decarboxylase
List aetiology/risk factors for porphyria cutanea tarda
Haemochromoatosis HIV Hepatitis C Alcohol Oestrogen excess Iron excess
List clinical features of porphyria cutanea tarda
Vesicles/bullae in sun-exposed sites Hypertrichosis Hyperpigmentation Skin fragility Scarring
What investigations would you do for porphyria cutanea tarda?
LFTs typically deranged
High serum ferritin
Plasma/faecal/urinary porphyrins
Which enzyme is deficient in erythropoietic porphyria?
Ferrochelatase
List clinical features of erythropoietic porphyria
Swelling
Burning pain
Young kid tingling/itchy skin in sunlight
Gallstones
Which enzyme is deficient in acute intermittent porphyria?
PBG deaminase
List aetiology/risk factors for acute intermittent porphyria
Autosomal dominant
Alcohol
Contraception (increased progesterone)
List clinical features of acute intermittent porphyria
Neuro + autonomic upset
Nausea
Pain
Outline treatment of porphyrias
Avoid sunlight Remove precipitants Venesection if ferritin high Support and education Haemarginate in AIP
What is psoriasis?
Chronic inflammatory skin condition involving uncontrolled epidermal proliferation (parakeratosis) and T-cell-driven inflammatory infiltration of epidermis and dermis
List aetiology/risk factors for psoriasis
Genetics, strong family history
Triggers (stress, infection, trauma, alcohol, obesity)
Smoking
Drugs (B-blockers, lithium, antimalarials)
TH1 + TH17 cells
List clinical features of psoriasis
Symmetrical well-defined itchy red plaques Scale Usually affects extensors Nail changes (pitting, onycholysis, subungual keratosis) Koebner phenomenon Auspitz sign Small plaques (guttate) in young Pustules if severe Psoriatic arthritis Erythroderma with systemic upset
What investigations would you do for psoriasis?
Skin biopsy for histology shows parakeratosis, epidermal proliferation and microabscesses with inflammatory infiltrate
Outline treatment for psoriasis
Education, avoid triggers/stressors Emollients for cooling Vitamin D analogue (calcipotriol) Topical steroid Coal tar preparations Short-term retinoid (Acitretin) Dithranol, tazarotene if unresponsive Immunosuppression (methotrexate, etanercept, infliximab) Phototherapy
List infective skin manifestations of HIV
HIV seroconversion disease Thrush Molluscum contagiosum Herpes Varicella zoster Cryptococcus Oral hairy leukoplakia
List inflammatory manifestations of HIV
Seborrhoeic dermatitis
Psoriasis
Eosinophillic folliculitis
What malignancy associated with HIV has prominent skin features?
Kaposi sarcoma
What causes Kaposi’s sarcoma?
Herpes hominis virus (HHV-8)
List clinical features of Kaposi’s sarcoma
Purpule macules
Papules, nodules
Plaques affecting skin and mucosa
Periorbital purpura (racoon eyes)
Outline treatment of Kaposi’s sarcoma
HAAR
Radiotherapy
Interferon-alpha
Dermatitis to latex is type 1 hypersensitivity. True/False?
True
Do skin prick IgE test, not patch test
What are halo naevi?
Immune reponse to a mole
Has a “fried egg” appearance
What are blue naevi?
Result due to melanocytes that failed to fully migrate from neural cell crest
What is Sturge Weber syndrome?
Port wine staining affects CN V1 nerve distribution
Associated with vascular malformations on ipsilateral side, including in the brain
What is Klippel Trenauney syndrome?
Capillary + venous malformation that causes progressive limb overgrowth with purpuric rash
If a strawberry naevus affects the eye in children, what might develop?
Ambliopia or other visual field defects - refer urgently to ophthalmology
How long do individual lesions of urticaria normally last?
Up to 24 hours
Acute urticaria: up to 6 weeks
Chronic urticaria: over 6 weeks
Which cell is responsible for releasing inflammatory mediators that cause urticaria?
Mast cell
List causes of urticaria
Allergy (not usually chronic) Direct chemicals Physical (dermographism, vibration, cold, solar) Autoimmune conditions Infection Dermatitis
What treatments are available to block the effects of mediators released from mast cells?
Antihistamines
Leukotriene antagonists
Serotonin antagonists
Which histamine receptors are relevant in urticaria?
H1
H2
H4
What is anaphylaxis?
Acute angioedema, often with urticaria, with respiratory compromise and hypotension
Life-threatening!
Outline treatment of anaphylaxis
Ensure airway patent (ABCDE) IM adrenaline IV antihistamine IV hydrocortisone IV fluids if hypotensive