Rashes, psoriasis and dermatitis Flashcards
what would you see on biopsy of a person with dermatitis
spongiosis
inflammatory cell infiltrate
biggest issue with a child with atopic dermatitis?
pruritus at night when sleeping
can cause insomnia and impaired cognitive function
what else is atopic dermatitis associated with
asthma
allergic rhinitis
food allergy
how would atopic dermatitis be seen in a patient with skin of colour
well defined, papular instead of macular, extensive lichenification
what is discoid eczema
well defined border, disc shaped
what is photosensitive eczema
dermatitis due to photosensitivity to certain wavelengths of light
what is stasis eczema
dermatitis due to increased hydrostatic pressure or oedema, commonly in the legs
what is pompholyx eczema
joining of pongiotic vesicles to create a larger vesicle that may weep
what is lichen simplex
not a disease, person scratches at an area so much it gives them dermatitis
causes of psoriasis (not the immunology of it)
genes
stress
drugs - BB
Infection - strep throat
increases risk factors due to psoriasis?
3x MI diabetes hyperlipidaemia diabetes obesity depression chron's disease cancer psoriatic arthritis
what is koebner phenomenon
psoriasis in area of skin trauma
what is auspitz sign
pinpoint bleeding under scale due to elongated dermal papillae
pathogenesis of acne?
poral occlusion of pilosebaceous unit due to increased sebum
bacterial colonisation and dermal inflammation
what is wickham’s striae
lace like pattern on surface of papules and buccal mucosae
hallmark of lichen planus
what is nikolsky’s sign
shearing off of a blister
+ve is indicative of pemphigus vulgaris
why is mortality increased in pemphigus vulgaris
blister bursts easily so secondary bacterial infection
types of allergic drug reactions and their rashes involved
type I - urticaria
type II - pemphigus and pemphigoid
type III -purpura
type IV - maculopapular
true/false - allergic drug reactions are dose dependent
false - they are not
types of non-allergic drug reactions
eczema phototoxicity atrophy psoriasis xerosis erosion
most common drug rash
exanthemous - maculopapular
what type of hypersensitivity is an exanthemous drug reaction and what immune cell mediates it
type IV
t cell
when would you see an exanthemous rash present
4-21 days after being on a drug
when would an exanthemous rash become life threatening
wheeze blisters very high fever purpura facial erythema/oedema and genital involvement widespread confluent oedema
what drugs commonly cause exanthemous rashes
penicllin suphonamide erythromycin NSAIDs antiepileptics
an urticarial rash has two methods of pathophysiology, describe them and the drugs that happen
immediate IgE after exposure - beta lactams
direct mast cell mediator release - aspirin, opiates, NSAIDs, vancomycin
what can cause purputic rash
warfarin necrosis
what can cause an acneiform rash
glucocorticoids
androgens, lithium, isoniazid, phenytoin
what can cause drug induced bullous pemphigoid
ACEI, penicillin, furosemide
what drugs can cause pigmentation
minocyclone
hydroxyurea
who to consider for drug rash
any patient on medication with symmetrical skin rash
elderly, females, viral infection, genes
B-lactams, multiple drugs
what is a fixed drug eruption ans what causes it
well demarcated painful red round plaque, causes pigmentation when drug stiopped
doxy, paracetamol, NSAIDs
what causes toxic epidermal necrolysis
cephalosporins, sulphonimides, NSAIDs, sertraline, pantoprazole
what causes AGEP
antibiotics, CCB, antimalarials
consequences of DRESS, TEN, AGEP
hypothermia fluid loss protein loss sepsis multi organ failure
how do drugs cause phototoxic reactions
can act as a chromophore
managing drug reactions?
discontinue use alternative topical steroids and antihistamines for type I allergy bracelet tell MRHA
causes of pruritoceptive itch
lichen planus
asteatotic eczema
psoriasis
insect bite
causes of neuropathic itch
shingles
causes of neurogenic itch
haematological paraneoplastic liver/bile duct kidney disease thyroid disease
psychogenic itch is?
psychological
