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D22 Dermatology
Drug Eruptions Toronto Notes 2019 DRUG INDUCED URTICARIA AND ANGIOEDEMA
Clinical Presentation
• morphology:whealslasting>24hunlikenon-druginducedurticaria,angioedema(faceandmucous membranes)
• systemicfeatures:maybeassociatedwithsystemicanaphylaxis(bronchospasm,laryngealedema,shock)
• timecourse:h-dafterexposuredependingonthemechanism
Epidemiology
• secondmostcommoncutaneousdrugreaction
• commoncausativeagents:penicillins,ACEI,analgesics/anti-inflammatories,radiographiccontrastmedia
Management
• discontinueoffendingdrug,treatmentwithantihistamines,steroids,epinephrineifanaphylactic
SERUM SICKNESS-LIKE REACTION
Clinical Presentation
• morphology:symmetricalcutaneouseruption(usuallyurticarial)
• systemicfeatures:malaise,lowgradefever,arthralgia,lymphadenopathy
• timecourse:appears1-3wkafterdruginitiation,resolve2-3wkafterwithdrawal
Epidemiology
• moreprevalentinkids(0.02-0.2%)
• commoncausativeagents:cefaclorinkids;bupropioninadults
Management
• discontinueoffendingdrug±topical/oralcorticosteroids
Pustular
ACUTE GENERALIZED EXANTHEMATOUS PUSTULOSIS (AGEP)
Clinical Presentation
• morphology:extensiveerythematous,edematous,andsterilepustules
• systemicfeatures:highfever,leukocytosiswithneutrophilia
• spread:startsinfaceandintertriginousareas,spreadstotrunkandextremities • timecourse:appears1wkafterdruginitiation,resolves2wkafterwithdrawal
Epidemiology
• rare: 1-5/million
• commoncausativeagents:aminopenicillins,cephalosporins,clindamycin,calciumchannelblockers
Management
• discontinueoffendingdrugandsystemiccorticosteroids
Bullous
STEVEN-JOHNSON SYNDROME (SJS)/TOXIC EPIDERMAL NECROLYSIS (TEN)
Clinical Presentation
• morphology:prodromalrash(morbilliform/targetoidlesions±purpura,ordiffuseerythema), confluence of flaccid blisters, positive Nikolsky sign (epidermal detachment with shear stress), full thickness epidermal loss; dusky tender skin, bullae, desquamation/skin sloughing, atypical targets
• classification:BSAwithepidermaldetachment:<10%inSJS,10-30%inSJS/TENoverlap,and>30%in TEN
• spread:faceandextremities;maygeneralize;scalp,palms,solesrelativelyspared;erosionofmucous membranes (lips, oral mucosa, conjunctiva, GU mucosa)
• systemicfeatures:fever(higherinTEN),cytopenias,renaltubularnecrosis/AKI,trachealerosion, infection, contractures, corneal scarring, phimosis, vaginal synechiae
• time course: appears 1-3 wk after drug initiation; progression <4 d; epidermal regrowth in 3 wk • canhaveconstitutionalsymptoms:malaise,fever,hypotension,tachycardia
Epidemiology
• SJS: 1.2-6/million; TEN: 0.4-1.2/million
• riskfactors:SLE,HIV/AIDS,HLA-B1502(associatedwithcarbamazepine),HLA-B5801(associated
with allopurinol)
• commoncausativeagents:drugs(allopurinol,anti-epileptics,sulfonamides,NSAIDs,cephalosporins)
responsible in 50% of SJS and 80% of TEN; viral or mycoplasma infections
• prognosis:5%mortalityinSJS,30%inTENduetofluidlossandinfection
Urticarial
SCORTEN Score for TEN Prognosis
One point for each of: age ≥40, malignancy, body surface area detached ≥10%, tachycardia ≥120 bpm, serum urea >10 mmol/L, serum glucose >14 mmol/L, serum bicarbonate <20 mmol/L
Used to determine appropriate clinical setting: score 0-1 can be treated in non-specialized wards; score ≥2 should be transferred to intensive care or burn unit
Score at admission is predictive of survival: 94% for 0-1, 87% for 2, 53% for 3, 25% for 4, and 17% for ≥5