Dermatology Flashcards
Classic presentation of dermatitis herpetiformis
itchy papules and vesicles on extensor surfaces
diagnosis of dermatitis herpetiformis
immunoflorescence shows IgA deposits in the upper dermis
Management of dermatitis herpetiformis
gluten free diet
dapsone
acne rosacea treatment
mild/moderate - topical metronidazole
severe/resistant - oral tetracycline
features of acne rosacea:
where it affects, type of lesions
cheek face and forehead
initially flushing , telangectesia are common,
later develops into persistent erythema with papules and pustules
can lead to rhinophyma, and my have blepharitis
causes of erythema multiforme
- viruses: HSV (in 50% of cases), Orf (parapox virus)
- idiopathic
- bacteria: Mycoplasma, Streptococcus
- drugs: penicillin, sulphonamides, carbamazepine, allopurinol, NSAIDs, OCP, nevirapine
- connective tissue disease e.g. SLE
- sarcoidosis
- malignancy
features of erythema multiforme
target lesions
usually start on backs of hands/feet then spread to torso
more commonly upper limbs than lower limbs
mild pruritis
Definition of onycholysis
separation of the nail plate from the nail bed
Causes of onycholysis
trauma infection esp fungal skin disease eg psoriasis, dermatitis impaired circulation eg Raynauds hypo/hyper-thyroidism
define keyloid scar
tumour-like growth originating from connective tissue of a scar and extend beyond the border of the original wound
Risk factors for a keyloid scar
young
afrocarribean
common sites (most common first): sternum, shoulder, neck, face, extensor surfaces, trunk
Vitiligo:
- aeteology
- age of onset
- features
autoimmune loss of melanocytes –> hypopigmentation
1% of population, starts in 20-30s
well demarcated patches of depigmented skin, usually peripheries, trauma may precipitate new lesions (Koebner phenomenon)
Vitiligo associated conditions
T1DM Addisons disease, Autoimmune thyroid disorders, Pernicious anaemia, Alopecia areata
Management of vitiligo
sun block
topical steriods if applied early
Main complication of PUVA therapy for psoriasis
SCC
features of pyoderma gangrenosum
small papule ->deep red necrotic ulcer with violaceous border (gun metal grey)
typically on lower legs
may have systemic upset (fever, myalgia)
causes of pyoderma gangrenosum
idiopathic IBD RA, SLE myeloproliferative disorders lymphoma, myeloid leukaemias monoclonal gammopathy (IgA) primary biliary cirrhosis (DR3)
Mx of pyoderma gangrenosum
oral steroids +/- other immunosuppressants (eg infliximab)
Acanthosis nigricans disease associations
endo: diabetes mellitus, Cushing's disease, hypothyroid, acromegaly UC gastric cancers PCOS obesity Prader-Willi syn drugs: OCP, nicotinic acid
features and pathology of lichen sclerosus
inflammation of epidermis of genitals leads to atrophy and formation of itchy white plaques.
More common in elderly females
Mx of lichen sclerosus
biopsy to exclude other conditions (increased risk of vulval cancer)
topical steroids and emollients
features of lichen planus
purple papules that are pruritic
white cracks over the top (Wickham’s striae)
oral involvement common.
features of toxic epidermal necrolysis?
commonly due to
scalded appearance with friable epidermis
systemic upset - pyrexia, tachycardia
most commonly due to a drug reaction (penicillin, phenytoin, allopurinol, carbamazepine)
common drug precipitants of TEN?
phenytoin,
allopurinol
penicillins
carbamazepine
causes of scarring alopecia
trauma, burns, radiotherapy
lichen planus
discoid lupus
tinea capitis (if a kerion develops)
causes of non-scarring alopecia
male pattern baldness
drugs: cytotoxic, carbimazole, heparin, OCP, colchicine
nutritional:iron and zinc def
autoimmune: alopecia areata
telogen effluvium (hair loss following stressful time)
trichotillomania (pulling hair out)
classical features of pretibial myxoedema
symmetrical erythematous shin lesions with shiny orange peel skin
seen in Graves disease
classical features of Necrobiosis lipoidica diabeticorum
shiny, painless areas of yellow/red skin typically on the shin of diabetics
often associated with telangiectasia
Exacerbating factors for psoriasis
withdrawal of steroids
trauma
alcohol
beta blockers, lithium, NSAIDS, ACEi, antimalarials
Features of bullous pemphigoid
Itchy tense blisters, typically around flexures
Blisters heal without scarring
Rarely involves mucous membranes (NB differentiating feature with pemphigus)
Ix and Mx of bullous pemphigoid
Skin biopsy - IgG and C3 deposits at dermoepidermal junction
Oral corticosteroids
What are myxoid cysts and where are they usually found?
Associations?
Benign ganglion cysts on the dorsum of a distal phalanx
Usually have OA in surrounding joint
In middle aged females
Complications of psoriasis
Psoriatic arthritis Superimposed bacterial infection Metabolic syndrome Cardiovascular disease VTE
Pathology of bullous pemphigoid
Autoantibodies against hemidesmosomal proteins BP180 and BP230
Features of drug hypersensitivity syndrome
Mx
3-6 weeks after starting anticonvulsants or antimicrobials
fever, facial oedema, papulopustular rash, lymphadenopathy or hepatitis
associated eosinophilia
Rx with oral steroids
Association of necrolytic migratory erythema
glucagonoma
