Dermatology Flashcards
Define toxic epidermal necrolysis
Potentially life-threatening dermatological disorder characterised by widespread erythema, necrosis and bullous detachement of epidermis and mucous membranes
What is the milder form of TEN called?
Stevens-Johnson syndrome (<10% involvement)
What are the risk factors for TEN?
Children
HIV/AIDS
Drugs
What drugs can cause TEN?
Sulphonamides Phenobarbital Carbamazepine Lamotrigine Allopurinol
What is the aetiology of TEN?
Adverse drug reaction
Infection
Vaccination
Graft vs host disease
What are the symptoms of TEN?
Prodrome of cough, myalgia and anorexia 2-3 days before
Itching
Burning
Fever
What are the examination findings in TEN?
Involvement of mucosa and internal epithelial surfaces
Nikolsky’s sign
What is Nikolsky’s sign?
Slight rubbing of the skin results in exfoliation - occurs in TEN
What investigations can be done for a patient with suspected TEN?
Bloods - FBC, U&Es, CRP
Skin biopsy
Blood cultures
How is TEN managed?
ITU, burn, gynae, ophthalmology involvement
Stop all drugs
Analgesia and fluids
IVIG
What are the differential diagnoses for TEN?
Bullous pemphigoid
Bullous pemphigus
What are the complications of TEN?
Death Dehydration/malnutrition ARDS GI ulceration/perforation Infection Sepsis
What is the prognosis of TEN?
30-50% mortality
Define erythema multiforme
Acute hypersensitivity rash caused by infection or drugs
Usually mild but makor form can affect mucous membranes
What are the risk factors for EM?
History of EM or infection
Suspect drugs
Vaccinations - diphtheria, tetanus
What is the aetiology of EM?
HSV EBV Drugs - sulphonamide, anticonvulsants Mycoplasma Autoimmune HIV Wegener's Carcinoma, lymphoma
What features are seen on examination of a patient with EM?
Erythematous polycyclic/annular/concentric rings (target lesions)
May blister
Symmetrical rash
What investigations can be done for a patient with suspected EM?
Bloods - FBC, U&Es
Serology - HSV, VZV
M.pneumoniae titre
CXR
How is EM managed?
Treat underlying cause
Recurrent - aciclovir
Resistant - azathioprine
What are the differential diagnoses of EM?
TEN
SJS
What are the complications of EM?
Sepsis
Cellulitis
Permanent skin/eye damage and scarring
Inflammation of internal organs
What is the prognosis of EM?
Usually self-limiting
Can recur
How can EM be prevented?
Prophylactic antivirals for HSV
Define acute urticaria
Development of itchy weals/swellings in the skin due to leaky dermal vessels
AKA hives
What is the difference between urticaria and angio-oedema?
Angio-oedema involves sub-dermal vessels; life-threatening
Urticaria involves dermal vessels
What are the types of urticaria?
Cold Pressure Stress Heat/cholinergic Solar Aquagenic Contact
What are the risk factors for urticaria?
Atopy
Young age
What is the aetiology of urticaria?
Autoimmune Viral/parasitic infection Drug reaction Food allergy SLE Idiopathic
What drugs can cause urticaria?
NSAIDs
Penicillin
ACEi
Opiates
What would be the examination findings of a patient with urticaria?
Cutaneous swellings/weals, develop over a few minutes anywhere on the body and resolve spontaneously in minutes/hours
Lesions are intensely itchy and erythematous
How is urticaria managed?
Treat underlying cause Avoid salicylates and opiates Oral antihistamines (e.g. cetirizine)
How is angio-oedema managed?
IM adrenaline
IV steroids
What are the differential diagnoses for urticaria?
Blisters
Dermatitis
Insect bite
Drug reaction
What are the complications of urticaria?
Anaphylaxis
Airway blockage
What is the prognosis of urticaria?
Usually spontaneously resolves
May become chronic
How can urticaria be prevented?
Prophylactic antihistamines for predisposed individuals
Define erythroderma
Clinical state of inflammation/redness of all/most of the skin
What are the risk factors for erythroderma?
Male
Older age
What is the aetiology of erythroderma?
Atopic eczema Psoriasis Drugs Seborrhoeic eczema Idiopathic Rare - leukaemia, HIV, toxic shock syndrome
What drugs can cause erythroderma?
Sulphonamides Gold Sulfonylureas Penicillin Allopurinol Captopril
What are the symptoms of erythroderma?
Tight, itchy skin
Malaise
Pyrexia
Widespread lymphadenopathy
What signs are seen on examination of a patient with erythroderma?
Hair loss
Ectropion
Nail shedding
Pustules
How is erythroderma investigated?
Skin biopsy
How is erythroderma managed?
Keep patient warm Regular observation and fluid balance Swab for infection Stop drugs Bed rest Emollient/mild topical steroid
What are the complications of erythroderma?
Death Cardiac failure Hypothermia Fluid loss Hypoalbuminaemia Capillary leak syndrome
Define impetigo
Highly contagious superficial bacterial infection with yellow crusting most common in children
What are the risk factors for impetigo?
Age 2-5
Crowded conditions (schools)
Warm, humid weather
Broken skin
What bacteria are most commonly implicated in impetigo?
S.aureus
Group A β-haemolytic streptococcus
What does impetigo look like on examination?
Weeping, exudative areas with honey-coloured crust
How is impetigo investigated?
Nasal swabs (resistant infection)
How is impetigo managed?
Topical fusidic acid or oral antibiotics
What are the differential diagnoses for impetigo?
Bullous impetigo
Scabies
Give a complication of impetigo
Cellulitis
What is the prognosis of impetigo?
Self-limiting and mild
How can impetigo be prevented?
Good personal hygiene
Avoid direct contact with affected
Define tinea
Superficial fungal infection of skin/nails by dermatophytes
What is tinea more commonly known as?
Ringworm
Give a risk factor for tinea
Immunosuppression
What are the 3 main organisms implicated in tinea?
Microsporum
Epidermophyton
Trichophyton
What does tinea look like on examination?
Asymmetrical, scaly patches with central clearing
Advancing, scaly, raised edges
Vesicles/pustules may be present
How can tinea be investigated?
Skin scrapings
How is tinea managed?
Topical terbinafine or systemic terbinafine/itraconazole
What are the differential diagnoses for tinea?
Nummular eczema
Granumola annulare
Psoriasis
Contact dermatitis
What are the complications of tinea?
Bacterial superinfection
General invasion of dermatophyte infection
What is the prognosis of tinea?
Curable
How can tinea be prevented?
Good skincare
Not sharing things with people who are affected
Define soft tissue abscess
Infection in the dermis/fat with development of walled off infection
What 2 organisms are most commonly implicated in soft tissue abscesses?
S.aureus
S.pyogenes
How are soft tissue abscessed managed?
Surgical drainage
Antibiotics if severe infection
Define cellulitis
Infection involving the dermis, mostly on the lower limb
What 2 organisms are most commonly implicated in cellulitis?
S.aureus
β-haemolytic streptococci