Dermatology Flashcards
Acanthosis nigricans
Describes symmetrical, brown, velvety plaques that are often found on the neck, axilla and groin
Causes
gastrointestinal cancer
diabetes mellitus
obesity
polycystic ovarian syndrome
acromegaly
Cushing’s disease
hypothyroidism
familial
Prader-Willi syndrome
drugs: oral contraceptive pill, nicotinic acid
Acne Rosacea
Features
typically affects nose, cheeks and forehead
flushing is often first symptom
telangiectasia are common
later develops into persistent erythema with papules and pustules
rhinophyma
ocular involvement: blepharitis
sunlight may exacerbate symptoms/
Management
topical metronidazole may be used for mild symptoms (i.e. Limited number of papules and pustules, no plaques)
topical brimonidine gel may be considered for patients with predominant flushing but limited telangiectasia
more severe disease is treated with systemic antibiotics e.g. Oxytetracycline
recommend daily application of a high-factor sunscreen
camouflage creams may help conceal redness
laser therapy may be appropriate for patients with prominent telangiectasia
patients with a rhinophyma should be referred to dermatology
Acne
Acne vulgaris is a common skin disorder which usually occurs in adolescence. It typically affects the face, neck and upper trunk and is characterised by the obstruction of the pilosebaceous follicles with keratin plugs which results in comedones, inflammation and pustules.
A simple step-up management scheme often used in the treatment of acne is as follows:
single topical therapy (topical retinoids, benzoyl peroxide)
topical combination therapy (topical antibiotic, benzoyl peroxide, topical retinoid)
oral antibiotics:
tetracyclines: lymecycline, oxytetracycline, doxycycline
tetracyclines should be avoided in pregnant or breastfeeding women and in children younger than 12 years of age
erythromycin may be used in pregnancy
minocycline is now considered less appropriate due to the possibility of irreversible pigmentation
a single oral antibiotic for acne vulgaris should be used for a maximum of three months
a topical retinoid (if not contraindicated) or benzoyl peroxide should always be co-prescribed with oral antibiotics to reduce the risk of antibiotic resistance developing. Topical and oral antibiotics should not be used in combination
Gram-negative folliculitis may occur as a complication of long-term antibiotic use - high-dose oral trimethoprim is effective if this occurs
combined oral contraceptives (COCP) are an alternative to oral antibiotics in women
as with antibiotics, they should be used in combination with topical agents
Actinic keratoses
Actinic, or solar, keratoses (AK) is a common premalignant skin lesion that develops as a consequence of chronic sun exposure
Features
small, crusty or scaly, lesions
may be pink, red, brown or the same colour as the skin
typically on sun-exposed areas e.g. temples of head
multiple lesions may be present
Management options include
prevention of further risk: e.g. sun avoidance, sun cream
fluorouracil cream: typically a 2 to 3 week course. The skin will become red and inflamed - sometimes topical hydrocortisone is given following fluorouracil to help settle the inflammation
topical diclofenac: may be used for mild AKs. Moderate efficacy but much fewer side-effects
topical imiquimod: trials have shown good efficacy
cryotherapy
curettage and cautery
Alopecia
Alopecia may be divided into scarring (destruction of hair follicle) and non-scarring (preservation of hair follicle)
Scarring alopecia
trauma, burns
radiotherapy
lichen planus
discoid lupus
tinea capitis*
Non-scarring alopecia
male-pattern baldness
drugs: cytotoxic drugs, carbimazole, heparin, oral contraceptive pill, colchicine
nutritional: iron and zinc deficiency
autoimmune: alopecia areata
telogen effluvium
hair loss following stressful period e.g. surgery
trichotillomania
Anti-histamines
Loratadine and cetirizine are non-sedating antihistamines meaning they are less sedating than alternatives such as chlorpheniramine
Important for meLess important
Loratadine is a non-sedating antihistamine - although it can cause sedation it is less likely to do so than other medications.
Chlorphenamine and promethazine are both useful antihistamines but are more likely to cause sedation than loratadine.
Buclizine is an antihistamine although it is more commonly used as an anti-emetic (in combination with paracetamol) for the relief of migraines.
Mirtazapine has antihistamine properties but is used primarily as an antidepressant and appetite stimulant.
Antihistamines (H1 inhibitors) are of value in the treatment of allergic rhinitis and urticaria.
Examples of sedating antihistamines
chlorpheniramine
As well as being sedating these antihistamines have some antimuscarinic properties (e.g. urinary retention, dry mouth).
Examples of non-sedating antihistamines
loratidine
cetirizine
Of the non-sedating antihistamines there is some evidence that cetirizine may cause more drowsiness than other drugs in the class.
Basal cell carcinoma
Basal cell carcinoma (BCC) is one of the three main types of skin cancer. Lesions are also known as rodent ulcers and are characterised by slow-growth and local invasion. Metastases are extremely rare. BCC is the most common type of cancer in the Western world.
Features
many types of BCC are described. The most common type is nodular BCC, which is described here
sun-exposed sites, especially the head and neck account for the majority of lesions
initially a pearly, flesh-coloured papule with telangiectasia
may later ulcerate leaving a central ‘crater’
Referral
generally, if a BCC is suspected, a routine referral should be made
Management options:
surgical removal
curettage
cryotherapy
topical cream: imiquimod, fluorouracil
radiotherapy
Bullous disorders
Causes of skin bullae
congenital: epidermolysis bullosa
autoimmune: bullous pemphigoid, pemphigus
insect bite
trauma/friction
drugs: barbiturates, furosemide
Bullous pemphigoid
Bullous pemphigoid is an autoimmune condition causing sub-epidermal blistering of the skin. This is secondary to the development of antibodies against hemidesmosomal proteins BP180 and BP230
Bullous pemphigoid is more common in elderly patients.
Features include
itchy, tense blisters typically around flexures
the blisters usually heal without scarring
mouth is usually spared*
Skin biopsy
immunofluorescence shows IgG and C3 at the dermoepidermal junction
Management
referral to dermatologist for biopsy and confirmation of diagnosis
oral corticosteroids are the mainstay of treatment
topical corticosteroids, immunosuppressants and antibiotics are also used
Burns pathology
Extensive burns
Haemolysis due to damage of erythrocytes by heat and microangiopathy
Loss of capillary membrane integrity causing plasma leakage into interstitial space
Extravasation of fluids from the burn site causing hypovolaemic shock (up to 48h after injury)- decreased blood volume and increased haematocrit
Protein loss
Secondary infection e.g. Staphylococcus aureus
ARDS
Risk of Curlings ulcer (acute peptic stress ulcers)
Danger of full thickness circumferential burns in an extremity as these may develop compartment syndrome
Eczema herpeticum
Eczema herpeticum describes a severe primary infection of the skin by herpes simplex virus 1 or 2.
It is more commonly seen in children with atopic eczema and often presents as a rapidly progressing painful rash.
On examination, monomorphic punched-out erosions (circular, depressed, ulcerated lesions) usually 1–3 mm in diameter are typically seen.
As it is potentially life-threatening children should be admitted for IV aciclovir.
Erythema multiforme
Erythema multiforme is a hypersensitivity reaction which is most commonly triggered by infections. It may be divided into minor and major forms.
Features
target lesions
initially seen on the back of the hands / feet before spreading to the torso
upper limbs are more commonly affected than the lower limbs
pruritus is occasionally seen and is usually mild
Causes
viruses: herpes simplex virus (the most common cause), Orf*
idiopathic
bacteria: Mycoplasma, Streptococcus
drugs: penicillin, sulphonamides, carbamazepine, allopurinol, NSAIDs, oral contraceptive pill, nevirapine
connective tissue disease e.g. Systemic lupus erythematosus
sarcoidosis
malignancy
Erythroderma
Erythroderma is a term used when more than 95% of the skin is involved in a rash of any kind.
Causes of erythroderma
eczema
psoriasis
drugs e.g. gold
lymphomas, leukaemias
idiopathic
Erythema nodosum
Overview
inflammation of subcutaneous fat
typically causes tender, erythematous, nodular lesions
usually occurs over shins, may also occur elsewhere (e.g. forearms, thighs)
usually resolves within 6 weeks
lesions heal without scarring
Causes
infection
streptococci
tuberculosis
brucellosis
systemic disease
sarcoidosis
inflammatory bowel disease
Behcet’s
malignancy/lymphoma
drugs
penicillins
sulphonamides
combined oral contraceptive pill
pregnancy
Fungal nail infections
Onychomycosis is fungal infection of the nails. This may be caused by
dermatophytes - mainly Trichophyton rubrum, accounts for 90% of cases
yeasts - such as Candida
non-dermatophyte moulds
Investigation
nail clippings
scrapings of the affected nail
the false-negative rate for cultures are around 30%, so repeat samples may need to be sent if the clinical suspicion is high
Management
do not need to be treated if it is asymptomatic and the patient is not bothered by the appearance
diagnosis should be confirmed by microbiology before starting treatment
dermatophyte infection:
oral terbinafine is currently recommended first-line with oral itraconazole as an alternative
6 weeks - 3 months therapy is needed for fingernail infections whilst toenails should be treated for 3 - 6 months
treatment is successful in around 50-80% of people
Candida infection:
mild disease should be treated with topical antifungals (e.g. Amorolfine) whilst more severe infections should be treated with oral itraconazole for a period of 12 weeks
if topical topical treatment is given treatment should be continued for 6 months for fingernails and 9-12 months for toenails