Dermatology Flashcards
erythema nodosum
painful blue-red lesions on the anterior shin
seen in sarcoidosis, TB, Crohn’s and leprosy
erythema multiforme
“target” lesions with central blisters
due to an autoimmune reaction to medications, infection, cancers (can be idiopathic)
erythema ab igne
brown-y discolouration due to heat/ intra-red exposure (often seen in pts with abdo pain that use hot water bottles)
can go on to develop SCC
dermatitis herpetiformis
autoimmune blistering due to IgA deposits in the dermis on the extensor surfaces
seen in coeliac disease
lichen’s sclerosis
inflammatory condition that usually affects the genitals
in females is very itchy and can increase risk of vulval cancer (give topical steroids and emollients)
in males occurs in uncircumcised, results in phimosis with a white ring around it
lichen’s planus
autoimmune inflammatory condition
purple, polygonal papules, pruritic (itchy)
saw tooth T-cell infiltration between dermis and epidermis
is associated with hepatitis C
acanthosis nigricans
symmetrical velvety brown plaques around body creases
due to insulin resistance (so seen in T2DM, Cushing’s, PCOS, Acromegaly, etc)
pityriasis rosea
acute self limiting rash often following a viral infection
begins with a herald patch then the rash develops to form a ‘Christmas tree’ distribution
strawberry haemangioma
AV malformation in new-born, will regress
cherry haemangioma
AV malformation that occurs with age, is benign, will not regress
hereditary haemorrhagic telangiectasia
aka Osler-Weber-Rendu syndrome
is autosomal dominant
causes multiple telangiectasia over skin and mucosa
malignant melanoma
Asymmetric Border is irregular Colours (2 or more) Diameter (often >6mm) Evolution of lesion
requires excision biopsy with margin
70% of cases are superficial spreading melanoma, nodular melanoma is the most aggressive type
squamous cell carcinoma of the skin
sun exposure
actinic keratoses is the premalignant version
immunosuppression, Marjolin’s ulcer, smoking, etc are risk factors
surgical excision with margin 4mm if <20mm or 6mm margin if >20mm
basal cell carcinoma
most common cancer in the western world
slow growth and local invasion of a lesion on sunexposed sites - may ulcerate to leave a central crater
surgical removal, curettage, cryotherapy, topical fluorouracil and radiotherapy
impetigo
superficial skin infection caused by staph aureus or strep pyrogenes
commonly in children on their faces
very contagious, golden crusted skin lesions (incubation period 4-10days)
Rx: topical fusidic acid, if extensive oral flucloxacillin
should be excluded from school until non-contagious ie 48hrs after starting treatment or when scabs have crusted over
cellulitis
due to strep pyrogenes or staph aureus
Eron classification
mild-moderate: flucloxacillin +/- clindamycin
severe: IV benzylpenicillin and flucloxacillin
necrotising fasciitis
medical emergency - must act FAST
needs radical debridement of tissue +/- amputation or is fatal, IV ABx (benzylpenicillin and clindamycin)
is caused by anaerobes/aerobes, clostridium or strep pyrogenes
(Fournier’s gangrene is NF localised to the scrotum and perineum)
Steven-Johnsons Syndrome
toxic epidermal necrolysis - allergic reaction to medication or infection (fatal in 5%) drug causes : PCP LAPSE phenytoin carbamazepine Phenobarbital Lamotrigine Allopurinol Penicillin Sulfa drugs Erthromycin
Acne vulgaris
occurs in up to 90% of adolescents
- -follicular epidermal hyperproliferation causes a keratin plug, this obstructs the pilosebaceous follicle allowing colonisation of anaerobic bacterium (Propionibacterium acnes) resulting in inflammation, comedones and pustules
Rx: topical OTC benzoyl peroxide, retinoids, ABx
oral ABx (doxycycline if bad)
COCP may help some
specialist can prescribe oral isotretinoin (teratogenic and increases suicide risk, need to monitor LFTs)
THERE IS NO ROLE FOR DIETARY MODIFICATION
acne fulminans
is a very severe acne with associated systemic upset, requires hospital admission for oral steroids
acne rosacea
is a chronic condition that affects the nose, cheeks and forehead
flushing, telangiectasia, blepharitis with persistent erythema, papules and pustules
Rx: mild - topical metronidazole, oral oxytetracycline if more severe, high factor daily sunscreen
laser therapy is prominent telangiectasia
treatment of fungal nail
oral terbinafine
shingles
reactivation of herpes zoster virus causing a painful, blistering rash of dermatomal distribution
vaccine is live-attenuated so CI in immunocompromised
Hutchinson’s sign (vesicles on tip of nose) indicate ophthalmic shingles will develop - requires specialist referral
Ramsey-Hunt syndrome = shingles of the facial nerve
Rx: oral acyclovir
urticaria
dermal swellings - “wheals”
acute <6 weeks - can be due to type 1 hypersensitivity reaction e.g. due to penicillin, cephalosporins, nuts, shellfish and eggs
(chronic >6 weeks usually idiopathic, avoid drugs that promote mast cell degranulation)
treatment: diphenhydramine (antihistamine)
drugs that promote mast cell degranulation = aspirin, NSAIDs, opioids and iodinated contrast
vitiligo
autoimmune destruction of melanocytes resulting in depigmentation of the skin
Rx: sun protection, topical corticosteroids if applied early, can depigment the unaffected area if widespread
eczema
IgE associated
Rx: topical emollients, steroids
oral antihistamines, flucloxacillin, steroids or azathioprine in severe cases
psoriasis
most commonly plaque psoriasis
T-cell driven inflammation
due to chronic keratinocyte hyperproliferation which causes chronic erythematous scaly patches (mainly on extensor surfaces),
exacerbated by trauma, alcohol, beta-blockers, lithium, NSAIDs, and steroid withdrawal
Rx: potent corticosteroids ad vitamin D analogues and emollients
guttate psoriasis
frequently triggered by a strep infection
causes multiple red, teardrop lesions
complications of psoriasis
psoriatic arthropathy (psoriatic arthritis)
increased incidence of metabolic syndrome
increased incidence of CVD
increased incidence of VTE
psychological distress
dermatomyositis
inflammatory disorder causing symmetrical, proximal muscle weakness and characteristic skin lesions
associated with CT disorders or underlying malignancy (ovarian, breast, lung)
ANA positive and anti-Jo1 antibody
Rx: systemic corticosteroid
(polymyositis = the same without the typical skin features)
Peutz-Jeghers Syndrome
autosomal dominant (STK11) condition characterised by numerous harartomatous polyps in the GI tract and associated pigmented "freckles" on the lips, face, palms and soles ~50% die from a GI cancer by 60 yers
Raynaud’s phenomenon
Raynaud’s disease is idiopathic and less severe
Raynaud’s phenomenon is caused by CT/vascular/haematological disease
triphasic: WHITE, BLUE then RED
Rx: nifedipine (CCB)
Ehlers-Danlos syndrome
autosomal dominant CT disorder affecting type III collagen –> joint hypermobility and elasticity
Marfans syndrome
autosomal dominant condition - defect of FBNI gene on chromosome 15 that codes for fibrillin-1
arm span:height ratio >1.05
death is often due to aortic dissection
Rx: annual ECHO, aneurysm repair when aortic diameter >5cm, beta-blockers and ACEi
Pellagra
due to niacin (B3) deficiency or due to isoniazid
features: dermatitis, diarrhoea, dementia, depression and death if not taking
Leucoplakia
is a diagnosis of exclusion
a premalignant condition - hard white spots on mucous membranes that can’t be rubbed off
Bullous pemphigoid
autoimmune condition with sub-dermal blistering of the skin (no mucosal involvement)
Pemphigus vulgaris
autoimmune destruction against desmoglein-3
mucosal ulceration is usually the first sign
Rx: steroids and immunosuppression
keratoacanthoma
a benign epithelial tumour, common with age, needs to be excised as differential is SCC
pityriasis versicolour
superficial cutaneous fungal infection caused by malassezia furfur
more noticeable following a suntan
Rx: topical ketoconazole
