drug induced rashes Flashcards
bulla vs vesicles
bulla - >1cm elevated circumscribed, fluid filled;
vesicles - <1cm elevated circumscribed fluid filled
important questions to ask when new presentation with a rash
- have they ever had this or smilar beflre;
- site
- any exposure to new drugs/creams/soaps etc.
- allergies
- any recent illness
- exacerbating/relieveing factors e.g sun
what is pseudopophyria
a bullous photodermatosis with the clinical and histologic features of porphyria cutanea tarda (PCT), in the absence of abnormalities in porphyrin metabolism -> photosensitive and heals with scars and milia
erythema multiforma major vs minor
major - fever + >1 mucosal membrane involved (mouthe, eye, genitals etc.);
minor - without (or with only mild) mucosal disease
what is a non-palpable discoloured lesion called
macule/papule
what drugs can cause SJS/TEN
- Abx - sulfonamides
- antifungals - imidazole
- antivrials - nevirapine
- allopurinol
- NSAIDs
- anti-convulsants - carbamazepine, phenytoin, lamotrigine etc.
most common cause of SJS
DRUGS
what can be used to score SJS
SCORTEN - age, malignancy, tachycardia, %body surface area involved; urea levels; bicarb levels
what skin layer is involved in urticaria
dermis
what is drug hypersensitivity syndrome (DRESS)
a severe reaction usually characterized by fever, rash, and multiorgan failure, occurring 1-8 weeks after drug introduction
DRESS blood results
increase eosinophils and atypical lymphocytes
what drugs can cause pigmentation
- amiodarone - slate grey
- antimalaria - blue/black/brown
- oestrogen/progesterone - hyperpigemented patches (melasma, often seen in pregnancy)
what drug can cause drug related necrosis
warfarin - on day 3-5, especially prone if protien C or S or antithrombin III deficiency
what are porphyrins
dark photosensitive pigments that play a key role in haem synthesis
3 drugs that cause reactions mimicing pemphigus vulgaris
catopril, penicillamine, ampicillin
