Dermatology Flashcards
Describe the appearance progression of Impetigo and which part of skin it affects
- superficial infection of epidermis
- erythematous macule -> vesicle/pustule -> superficial erosion with golden crust
What is the treatment for impetigo?
- topical mupirocin 2% or fusidic acid 2%
- oral or IV flucloxacillin
NB: v contagious
Ecthyma is a skin infection affecting which level of the skin?
(aka deep impetigo)
-full thickness of epidermis infected
Describe the appearance of ecthyma
Crusted sores with underlying ulcers and deep erosions
-often on buttocks, thighs, legs, feet..
Erysipelas is a skin infection affecting which layer?
-the upper half of the dermis
Erysipelas: upper half of dermis infection
-how can it present?
- well demarcated red oedematous skin (+/-blisters in centre)
- unwell pt with fever, rigors, malaise
- portal of entry almost always found e.g. leg ulcer, tinea pedis, eczema
What organisms usually cause bacterial skin infections?
Staph Aureus
Group A strep, Strep Pyogenes
What level of skin does cellulitis affect?
-infection of lower half of dermis
Describe how cellulitis can present/what the redness appears like?
- pt has red, hot, swollen skin that is less well defined
- fewer/no blisters
- low grade fever poss
- bilateral leg cellulitis = v v rare
- lymphangitis and lymphadenopathy more common
What is “bilateral cellulitis” actually usually? What signs can occur in this?
Venous eczema
(normal venous scan poss as the incompetence if usually in the v small veins)
-peripheral oedema, venous ulcers, dry itchy, flaky skin, hemosiderin deposition
What level does necrotising fascitis affect?
Infection of the subcutaneous fat and the deep fascia
How does necrotising fascitis present? How does this change over 48hrs?
- red, hot swollen area of skin, looks like cellulitis
- within 48hrs, skin blisters, goes purple (cyanosis) or black (necrotic), crepitus (surgical emphysema)
- sever pain out of proportion to clinical signs
In what pt groups should you have a high suspicion of necrotising fascitis if they present with a cellulitis looking rash?
-Diabetics
-Immunocompromised
-Alcoholics
-Cancer
(but 50% pts are previously healthy)
Why are antibiotics alone useless in necrotising fascitis? Therefore what is the treatment along with IV abx?
The blood vessels in the skin are thrombosed from the inflamm/infection so the IV abx can’t travel in blood vessels to the area.
-Surgery - remove all the necrotic rx
Where does HSV1 occur? Often when? And appearance?
- around mouth
- can occur recurrently post: fever/menstruation/sun exposure/stress
- clusters of vesicles, break down and form crusts
- takes 7-10days to heal
What does HSV2 cause? Appearance?
Genital ulcers
Grouped vesicles on the genitalia, break down to form ulcers
Can be v v painful
How is HSV treated? Timeframe?
- HSV1 - often no rx needed, can give 5% aciclovir cream but only effective if used early (before vesicle established)
- HSV2: oral aciclovir 200mg x5 daily for 1 week
Herpes varicella zoster causing chicken pox, has an incubation period of approx __days, and
presents with what kind of rash?
- 14days
- itchy centripetal rash on trunk and face
- starts with vesicle appearance like a drop of water on an erythematous base then crusts over
- crops of macules, papules, vesicles, pustules and crusts all at the same time. Itchy
Describe a shingles rash and the timing of the rash and pain
- unilateral v. painful rash along course of a dermatome made up of grouped vesicles
- pain occurs before rash (~3days before)
- heals in 3-4weeks
- vaccine available for elderly/immunocompromised
What is the treatment for shingles? What specialty may need to be involved - why?
- regular analgesics e.g. gabapentin, tricyclic antidepressants
- aciclovir 800mg x5daily for a week, but must be given within 48-72hrs of vesicle onset
- OPTHALMOLOGY if affecting V1 ophthalmic nerve area, infection can affect cornea–>inflammation and blindness
What is eczema herpeticum?
- complication of existing eczema, gets much worse
- vesicles/ vesico-pustules or punched out haemorrhagic erosions that can be clustered as ulcers
- painful and itchy
- involve opthalmology if affecting near eye
What is eczema herpeticum?
- complication of existing eczema
- vesicles/vesico-pustules –> haemorrhagic punched out erosions –> heal clustered as ulcers
- painful and itchy
- involve ophthalmology if affecting eye area
What is the treatment for eczema herpeticum? What eczema cream will need to be held temporarily while the treatment is given?
- oral or IV aciclovir (as is viral)
- +/- abx (as with itching and ulcers, often a 2dry bacterial infection arises)
- hold topical steroids as impedes infection healing
What is the medical term for dandruff? and overgrowth of which yeast causes it?
- suborrheic dermatitis (around eyebrows, side of nose, around mouth)
- overgrowth of malassezia yeasts
Dandruff (suborrheic dermatitis) is caused by overgrowth of malessezia yeasts, what other fungal skin condition is caused by this organism?
- pityriasis versicolor
- hypo or hyperpigmented macules usually on trunk/back
- with a thin scale over the top
- heals on its own, or treat with ketoconazole shampoo
Dandruff (suborrheic dermatitis) is caused by overgrowth of malessezia yeasts, as is pityriasis versicolor, what shampoo can treat these conditions?
ketoconazole or selenium sulphide shampoo
Candida (thrush) causes nappy rash and oral candida is common in inpatients, if its persistents, what 2 things should be considered/ruled out?
- immunosuppression e.g HIV
- inherited mucocutaneous syndromes
Interitigo refers to any rash in which part of the body? What yeast is the common causative organism? Desribe the usual rash appearance:
- rash in body folds (more in overweight)
- candida albicans (treat w anti-fungal creams + weight loss)
- rapid developing itchy, moist rash with white peeling skin
Tinea corporis is a mould (dermatophyte) type of fungal infection, describe the rash appearance and 2 risk factors for it’s devlopment:
- annular rash (circular-paler in centre) spreads centrifugally
- scaly leading edge
- RFs: immunosuppression, diabetes, moist environments
An annular rash (circular-paler in centre) with a scaly leading edge is likely to be what? Name an organism that can cause this.
-tinea corporis (mould fungal infection: trichophyton rubrum commonest cause)
Tinea corporis affects the body, what area does tinea cruris affect
The groin
Why is the dermatophyte infection tinea capitis important to treat? What is a kerion?
-v common in 3-7yrs, if untreated in children, can have permanent hair loss
-kerion: boggy ball of fungus on scalp can be sore and crusty +/- enlarged lymph nodes
NB: most common organism: trichophyton tonsurans
What is tinea incognito? Why is it called this?
- inappropriate use of steroid cream (when rash is suspected to be eczema), steroid cream leads to more dermatitis/pustules/expanding area as fungus can grow much more
- when you stop the steroids, the dermatitis part gets worse so pts want to use steroids again, but important to stop steroids and give pt anti-fungal creams
What is the treatment for the scabies mite? Female burrows into epidermis and lays eggs, allergy is to the mite excreta/eggs
- permethrin
- malathion