dermatology Flashcards
what is erythema multiforme
acute self-limiting (resolves on its own without treatment) skin (‘muco-cutaneous’) condition caused by immune (allergic/hypersensitivity) reaction to some medications or infections – characterised by ‘target lesions’ (erythematous ring with a blister at the centre)
erythema multiforme: onset time
rapid: 24-48 hours
erythema multiforme: how long does it last for
1-2 weeks (resolves after this)
erythema multiforme: most common cause
infections (particularly HSV)
HSV (Herpes Simplex Virus) type 1 is the most common cause
erythema multiforme: subtypes and the difference b/w them
can be split into: minor and major
major = musocal involvement (lips and mouth)
erythema multiforme: clinical features
- target lesions
- initially: backs of hands/feet → torso
- upper limbs affected more commonly affected than lower limbs
- *pruritus occasionally seen - mild *
what viral infections can cause erythema multiforme
HSV (most common cause), Orf
Orf = skin disease of the sheep and goats caused by a parapox virus
what bacterial infections can cause erythema multiforme
mycoplasma (pneumonia), streptococcus
what medications can cause erythema multiforme
- sulfonamides
- penicillin (inc co-amoxiclav)
- carbemazapine (seizures)
- allopurinol (gout)
- NSAIDs
- OCP
- nevirapine (HIV)
erythema multiforme: causes
- viral infection
- bacterial infection
- idiopathic
- medications
- ct disorders e.g. SLE
- saroidosis
- malignancy
pityriasis rosea: typical presentation
can follow URTI - presents w herald patch first → rash along skin tension lines
guttate psoriasis: typical presentation
- commonly affects teenagers
- often follows streptococcal throat infection
- acute-onset widespread rash (sometimes tear-drop shaped) along torso and limbs
