Dermatology Flashcards
(119 cards)
Causes of acanthosis nigricans
type 2 diabetes mellitus
Addisons disease
gastrointestinal cancer
obesity
polycystic ovarian syndrome
acromegaly
Cushing’s disease
hypothyroidism
familial
Prader-Willi syndrome
drugs- combined oral contraceptive pill, nicotinic acid
Typical features of acne vulgaris
Comedones are due to a dilated sebaceous follicle
-if the top is closed a whitehead is seen
-if the top opens a blackhead forms
Inflammatory changes seen in acne vulgaris
papules
pustules
An excessive inflammatory response may result in:
nodules
cysts
NB- eventually scars may form eg. ice pick scars, hypertrophic scars
Management of acne vulgaris
Mild- benzoyl peroxide, topical antibiotics, and topical retinoids
Moderate- oral antibiotics, and anti-androgens (in females) eg. COCT (Dianette- risk of VTE)
Severe- oral retinoids (eg. isoretinoin)
NB- ABX of choice: tetracyclines: lymecycline, oxytetracycline, doxycycline (erythromycin in pregnancy, breastfeeding, children under 12)
NB- pregnancy is contraindicated to oral or topical retinoids
Actinic keratoses
Pre-malignant skin lesions that form as a result of chronic sun exposure;
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 of actinic keratoses
Lifestyle- sun avoidance, sun cream
Medical- fluorouracil cream (sometimes topical hydrocortisone is given following fluorouracil to help settle the inflammation), topical diclofenac, topical imiquimod, cryotherapy
Surgery- curettage and cautery
BCC
Most common cancer in the Western world
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’
Management;
surgical removal
curettage
cryotherapy
topical cream: imiquimod, fluorouracil
radiotherapy
Bowens disease
Bowen’s disease is a type of precancerous dermatosis that is a precursor to squamous cell carcinoma. It is more common in elderly patients. There is around a 5-10% chance of developing invasive skin cancer if left untreated.
red, scaly patches
often 10-15 mm in size
slow-growing
often occur on sun-exposed areas such as the head (e.g. temples) and neck, lower limbs
Management of Bowens disease
-may sometimes be diagnosed and managed in primary care if clear diagnosis or repeat episode
-topical 5-fluorouracil (typically used twice daily for 4 weeks, often results in significant inflammation/erythema. Topical steroids are often given to control this)
-cryotherapy
-excision
Bullous Pemphigoid
An autoimmune condition causing sub-epidermal blistering of the skin.
itchy, tense blisters typically around flexures
the blisters usually heal without scarring
there is usually no mucosal involvement (i.e. the mouth is spared)*
investigation- immunofluorescence shows IgG and C3 at the dermoepidermal junction
Management- refer to dermatology, oral steroids and immunosuppressants, also oral steroids and ABX
Assessing extent of a burn
Lund and Browder chart: the most accurate method
Which burns are referred to secondary care
all deep dermal and full-thickness burns.
superficial dermal burns of more than 3% TBSA in adults, or more than 2% TBSA in children
superficial dermal burns involving the face, hands, feet, perineum, genitalia, or any flexure, or circumferential burns of the limbs, torso, or neck
any inhalation injury
any electrical or chemical burn injury
suspicion of non-accidental injury
Initial burn management
superficial epidermal: symptomatic relief - analgesia, emollients etc
superficial dermal: cleanse wound, leave blister intact, non-adherent dressing, avoid topical creams, review in 24 hours
severe/full thickness: IV fluids, stabilise airway, escharotomy/plastics input
Cherry haemangioma
erythematous, papular lesions
typically 1-3 mm in size
non-blanching
not found on the mucous membranes
Chronic plaque psoriasis
Chronic plaque psoriasis is the most common form of psoriasis seen in clinical practice, accounting for around 80% of presentations.
erythematous plaques covered with a silvery-white scale
typically on the extensor surfaces such as the elbows and knees. Also common on the scalp, trunk, buttocks and periumbilical area
clear delineation between normal and affected skin
plaques typically range from 1 to 10 cm in size
if the scale is removed, a red membrane with pinpoint bleeding points may be seen (Auspitz’s sign)
50% have associated nail changes (e.g. pitting, onycholysis)
Contact dermatitis
irritant contact dermatitis: common - non-allergic reaction due to weak acids or alkalis (e.g. detergents). Often seen on the hands. Erythema is typical, crusting and vesicles are rare
allergic contact dermatitis: type IV hypersensitivity reaction. Uncommon - often seen on the head following hair dyes. Presents as an acute weeping eczema which predominately affects the margins of the hairline rather than the hairy scalp itself. Topical treatment with a potent steroid is indicated
Dermatitis herpetiformis
An autoimmune blistering skin disorder associated with coeliac disease. It is caused by deposition of IgA in the dermis.
Features- itchy, vesicular skin lesions on the extensor surfaces (e.g. elbows, knees, buttocks) and abdomen
Diagnosis- skin biopsy: direct immunofluorescence shows deposition of IgA in a granular pattern in the upper dermis
Management
-gluten-free diet
-dapsone
Deramtofibroma
solitary firm papule or nodule, typically on a limb
typically around 5-10mm in size
overlying skin dimples on pinching the lesion
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. May have itchy vesicles that contain pus. May have lymphadenopathy
As it is potentially life-threatening children should be admitted for IV aciclovir.
Erysipelas
Erysipelas is localised skin infection caused by Streptococcus pyogenes. In simple terms, it is a more superficial, limited version of cellulitis.
The treatment of choice is flucloxacillin.
Erythema ab igne
Erythema ab igne is a skin disorder caused by over exposure to infrared radiation. Characteristic features include reticulated, erythematous patches with hyperpigmentation and telangiectasia. A typical history would be an elderly women who always sits next to an open fire.
If the cause is not treated then patients may go on to develop squamous cell skin cancer.
Erythema multiforme
a hypersensitivity reaction which is most commonly triggered by infections. It may be divided into minor and major forms.
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
Features of erythema multiforme
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
NB- the more severe form, erythema multiforme major is associated with mucosal involvement.
Erythema nodosum
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