Reactive Erythemas Flashcards
Urticaria
cell of origin
mast cell
Urticaria
what do mast cells release to cause the rxn?
histamine
Urticaria
what type of hypersensitivity rxn is this?
type 1
Urticaria
describe the condition
- vascular rxn of the upper epidermis characterized by wheals surrounded by an erythematous halo
Urticaria
common causes
7
- idiopathic
- infection
- food rxn
- drug rxn
- IV admin of blood products/contrast dye
- physical causes (pressure, cold/heat, water, sunlight, exercise, emotion)
- autoimmune
Urticaria
Clinical Manifestations
- ITCH
- lesions appear over the course of minutes, enlarge, and then disappear (within 12 hrs)
- blanch w/ pressure
Urticaria
tx
First Line: 1st gen antihistamines
in real life, 2nd gen antihistamines more commonly used
Urticaria
considerations when prescribing 1st gen antihistamines
- cause sedation & require dosage adjustment in children, elderly, renal, hepatic impairement, resp disease, BPH, glaucoma
Angioedema
what type of hypersensitivity rxn causes this?
Type 1 rxn
Angioedema
located where compared to the urticaria?
- deep dermis and subcutaneous tissue
Angioedema
check for what type of med use?
ACE inhibitors
Angioedema
clinical manifestations
4 components
- trademark swelling: most commonly affects the face (lips, cheeks, periorbital areas) or portion of extremity
- concerning if the tongue, pharynx, larynx, and bowels are affected
- may be painful or burning (not pruritic)
- can last several days
Angioedema
Tx
- IV or oral glucocorticoids + 1st gen antihistamines
- Epinephrine if severe
Stevens-Johnson Syndrome
AKA
Toxic Epidermal Necrolysis
Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis
what is associated w/ poor prognosis?
- increasing age
- comorbidities
- greater extent of skin involvement
Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis
Assoicated w/ which meds
- sulfa drugs
- allopurinol
- tetracyclines
- anticonvulsants
- NSAIDS
Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis
If med induced, when will sx appear?
within the first 8 wks after drug initiation
Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis
Clinical Manifestations
- eruption is symmetric
- pain is prominent
- epidermis easily detaches at pressure points
- mucous membrane involvement
Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis
where does eruption of rash typically begin? does it spread? where?
begin on the face, upper trunk, and proximal extremities then spreads to rest of the body.
Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis
what does pain in lesions signify?
necrosis
Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis
describe initial lesions
- erythematous, irregularly shaped, dusky red to pruritic macules
Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis
what do lesions evolve to?
- progressively coalesce
- evolve to flaccid blisters, which spread w/ pressure & break easily
Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis
when the epidermis is peeled back, what is exposed?
- erythematous, oozing dermis
Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis
classifications by BSA
SJS vs SJS/TEN vs TEN
- SJS: < 10%
- SJS/TEN: 10-30%
- TEN: > 30%
Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis
Tx
- admission to burn unit
- stop offending medication
- IV corticosteroids, IV IG, cyclorsporine, enteraceept