Inflammatory Skin Disease + Infection Flashcards
what type of topical treatment is a semisolid emulsion of oil in water?
cream
what type of topical treatment is a semisolid grease/oil?
ointment
what type of topical treatment is a suspension/solution of medication in water, alcohol or other liquid?
lotion
what type of topical treatment is a semi-solid, thickened, aqueous lotion containing high molecular weight polymers?
gel
what is the purpose of an emollient?
enhances rehydration of epidermis
in what type of skin conditions are emollients prescribes?
dry/scaly conditions
in what type of skin conditions are wet wrap therapies prescribed?
very dry (xerotic) skin
compare the routes of antiviral administration for herpes simplex (eg cold sore or genital wart), eczema herpeticum, herpes zoster (shingles)?
HSV (cold sore/wart)- topical antiviral
eczema herpeticum- oral antiviral
herpes zoster- oral antiviral
what is hyperkeratosis?
increased thickness of keratin layer
what is parakeratosis?
persistence of nuclei in the keratin layer?
what is acanthosis?
increased thickness of epidermis
why does parakeratosis occur?
cells turn over more quickly, no time for nuclei to disappear
what is papillomatosis?
a type of acanthosis (increased thickness of epidemis) where you get wiggly epidermis (ie irregular)
what is spongiosis?
oedema between keratinocytes
why does spongiosis occur?
water has leaked out of keratinocytes because of inflammation
is papillomatosis a feature of eczema?
no
is spongiosis a feature of eczema?
yes
what happens to the dermatitis/eczema plaques in the chronic phase? (ie after itching)
thicken (lichenification) and become elevated
what is the pathogenesis of the contact allergic type of dermatitis?
delayed type 4 hypersensitivity reaction
what is the pathogenesis of the contact irritant type of dermatitis?
non-specific trauma
what is the pathogenesis of the atopic type of dermatitis? (eczema)
genetics + environmental factors causing inflammation
what is the pathogenesis of the drug-related type of dermatitis?
type 1 (IgE mediated) or type 4 (delayed) hypersensitivity reaction
what is the pathogenesis of the photo-induced/photosensitivity type of dermatiits?
reaction to UV light
what is the pathogenesis of the lichen simplex type of dermatitis?
physical trauma to scratching the skin
what is the pathogenesis of stasis dermatitis?
physical trauma to hydrostatic pressure
ie can be caused by immobility- hydrostatic pressure within blood vessels causes oedema then dermatitis
when the cause of contact allergic dermatitis is not clear, what test can be done?
patch testing
describe the plaques of atopic eczema?
ill-defined red and scaly
what type of distribution is seen in atopic eczema?
mainly flexural distribution
in the very young it can be on extensor surfaces
what is excoriation?
breaks in skin caused by scratching
what is the most common cause of secondary infection of atopic eczema? (ie after excoriation)
staph aureus
what is a typical sign of staph aureus secondary skin infection? (ie after excoriation)
crusting
what is the classic feature of eczema herperticum?
monomorphic punched out lesions
what does monomorphic mean?
each lesion is of the same size
what is discoid eczema?
eczema with well-defined lesions
what is the most common contact allergen in the UK?
nickel
what is pompholyx eczema?
eczema restricted to hands and feet
is pompholyx eczema acute or chronic?
always acute
compare Staph aureus to all other Staph species in terms of presence of coagulse?
Staph aureus = coagulase positive
all other staph = coagulase negative
what species of Staph is known as golden Staph?
Staph aureus
what is the function of coagulase?
an enzyme which Staph aureus contains
clots plasma
what type of Staph causes UTIs in women of child bearing age/
Staph. saprophyticus
what are the 2 important categories of beta-haemolytic strep?
group A strep (strep pyognes)
group B strep
what are the 2 important categories of alpha-haemolytic strep?
strep pneumoniae
strep viridans
where do non-haemolytic Strep commonly cause infection?
urinary tract infections
where in the body are non-haemolytic Strep commensals?
bowel
what are the 2 most common pathogens causing impetigo?
Staph aureus
GAS (strep pyogenes)
what population does Staphylococcal scalded skin syndrome usually occur in?
neonates
what pattern of redness does erysipelas give?
butterfly pattern
why can’t you tell whether the cause of erysipelas is Staph or Strep?
blood cultures are usually negative, no swabs available
what type of characteristic pain is seen with necrotising fasciitis?
pain disproportionally high to what can be clinically seen
what is the antibiotic of choice for treating sensitive strains of Staph aureus?
flucloxacllin
in addition to antibiotics, what else is required for the treatment of necrotising fasciitis?
immediate surgical debridement
what are the 2 types of necrotising fasciitis?
- caused by mixed anaerobes and coliforms
2. GAS
when does type 1 necrotising fasciitis tend to occur?
post abdominal surgery
what is a dermatophyte infection?
a fungal infection (ringworm)
what is tinea capitis?
ringworm (fungal) infection of the scalp
what is tinea barbae?
ringworm (fungal) infection of the beard
what is tinea corporis?
ringworm (fungal) infection of the body
what is tinea manuum?
ringworm (fungal) infection of the hand
what is tinea unguium?
ringworm (fungal) infection of the nails
what is tinea cruris?
ringworm (fungal) infection of the groin
what is tinea pedis?
ringworm (fungal) infection of the foot
what is tinea pedis more commonly known as?
athlete’s foot
what type of skin do dermatophytes enter?
abraded or soggy skin
what type of tissues do dermatophytes infect?
keratinised only
eg skin, hair, nails
why can dermatophye lesions give a ‘ring’ appearance?
lesion grows outwards and heals in the centre
what is the main species of ringworm (dermatophyte) that infects humans?
trichophyton rubrum
what virus causes both chickenpox and shingles?
varicella zoster virus
which type of nerve roots does varicella virus remain latent within?
sensory nerve roots
is the reactivation distribution of herpes zoster virus dermatomal or myotomal?
dermatomal
what 2 groups of patients tend to get herpes zoster virus?
elderly
immunocompromised
compare the onset of pain to the onset of the rash with herpes zoster?
pain usually comes 1/2 days before the rash
what is post herpetic neuralgia?
pain associated with herpes zoster, greater than 4 weeks after getting infection
what is Ramsay Hunt syndrome?
herpes zoster virus associated with 7th cranial nerve causing facial palsy and also irritation of 8th cranial nerve
what type of vaccine is the vaccination for chickenpox?
live attenuated
what is herpetic whitlow?
HSV infection where the nail meets skin
what cranial nerve does the HSV virus remain dormant in/ can reactivate from?
trigeminal ganglion
compare HSV type 1 and type 2 in terms of oral/genital herpes?
type 1: main cause of oral herpes. 50% of genital herpes cases
type 2: rare cause of oral herpes. 50% of genital herpes cases
which type of HSV is more severe and more likely to recur?
HSV type 2
aciclovir is a HSV/VZV antiviral, why does it not eliminate latent virus?
it only affects replicating virus
what are the classic lesions of erythema multiforme?
target lesions with erythema
what causes erythema multiforme?
many triggers
- drugs
- infections
what types of HPV are most common in warts and veruccas?
1, 2, 3, 4
what types of HPV are most common in genital warts?
6, 11
what types of HPV are most associated with cervical cancer?
16, 18
compare the original HPV vaccine to the new HPV vaccine?
original protected against types 16 and 18
new protects against 6, 11, 16 and 18
what is herpangina?
blistering rash at the back of the mouth
what viruses cause herpangina?
enteroviruses
not herpes
what viruses cause hand foot and mouth disease in humans?
enteroviruses
what population are occupationally exposed to Orf?
farmers
Orf is a zoonosis from what animals?
sheep
what bacteria causes syphilis?
treponema pallidum
how do you diagnose primary syphilis?
swab of chancre for PCR
how do you diagnose secondary or tertiary syphilis?
blood test
where is the secondary syphilis rash prominent?
on palms of hands and soles of feet
in secondary syphilis, what can be seen on mucous membranes?
snail trail ulcers
what bacteria causes lyme disease?
borrelia burgdorferi
what is the treatment of lyme disease?
doxycycline or amoxicillin
what is the most common genodermatoses?
neurofibromatosis
what is the second most common genodermatoses?
tuberous scelrosis
what is the earliest cutaneous sign of tuberous sclerosis?
ash-leaf macule
is an ash leaf macule hyperpigmented or depigmented?
depigmented macule
what parts of the genes (exons or introns) are removed during transcription and splicing?
introns
what are the 3 types of epidermolysis bullosa?
simplex
junctional
dystrophic
compare epidermolysis bullosa simplex, junction and dystrophic in terms of where pathology lies?
simplex- pathology in epidermis
junctional- pathology in DE junction
dystrophic- pathology in dermis
1/2 cafe au lait macules can be normal, what does more than 5 suggest?
genetic disease
what is the ground substance within dermis made of?
hyaluronic acid and chondroitin sulphate
what are the 4 main subtypes of inflammatory skin diseases?
- spongiotic
- psoriasiform
- lichenoid
- vesiculobollous
what happens to the epidermis in psoriasiform inflammation?
acanthosis due to elongation of rete ridges
what happens in lichenoid inflammation?
basal layer damage
what happens in vesiculobullous inflammation?
blistering
what subtype of inflammatory skin disease does eczema, contact allergic dermatitis and photosensitivity come under?
spongiotic inflammation
what subtype of inflammatory skin disease does psoriasis come under?
psoriasiform inflammation
what subtype of inflammatory skin disease does lichen planus and lupus come under?
lichenoid inflammation
what subtype of inflammatory skin disease does pemphigoid pemphigus and dermatitis herpetiformis come under?
vesiculobullous inflammation
what is koebner phenomenon? (in relation to psoriasis)
when new psoriatic lesions arise at sites of trauma
describe psoriatic lesions?
well demarcated, erythematous, scaly plaques
describe the distribution of psoriasis?
extensor surfaces
there are 4 types of pemphigus, which is most common?
pemphigus vulgaris
what is acantholysis?
break down of intracellular adhesion sites
compare bullous pemphigoid and pemphigus in terms of acantholysis?
pemphigus has acantholysis
pemphigoid doesn’t
compare bulloud pemphigoid and pemphigus in terms of the target of autoantibodies?
pemphigoid- antigens in hemidesmosomes
pemphigus- antigens in desmosomes
what disease is dermatitis herpetiformis strongly associated with?
coeliacs disease
what is the treatment od dermatitis herpetiformis?
gluten free diet
compare the type of autoantibodies of pemphigus, pemphigoid and dermatitis herpetiformis?
pemphigus- IgG
pemphigoid- IgG
dermatitis herpetiformis- IgA
describe whiteheads and blackheads in terms of comedones?
whitehead- closed comedone
black head- open comedone
is angioedema pitting or non-pitting?
non- pitting
in what type of allergic reaction are serum tryprase levels raised?
anaphylaxis
what type of nerve fibres transmit itch?
C fibres
unmyelinated
what are the 4 causes of itch?
pruritoceptive
neuropathic
neurogenic
psychogenic
what causes a pruritoceptive itch?
something in skin triggers itch
what causes a neuropathic itch?
damage of any sort to central or peripheral nerves causing itch
what causes a neurogenic itch?
no evident CNS damage, but itch caused by effects on CNS receptors
what type of itch do systemic diseases with associated pruitus usually cause?
neurogenic itch