Dermatology Flashcards
What type of eczema is the most common?
Atopic (Type I hypersensitivity) - 20% children will develop
IgE cross-links and then degranulates –> histamine and prostaglandins into epidermis –> maculopapular rash
Others:
Irritant
Contact (type IV hypersensitivity)
How does the clinical presentation change with age?
Infant = facial lesions and patchy elsewhere
Older child = lesions on flexures (elbow and knees) and wrists and ankles
Mid-teens = May clear, remain or change pattern:
Can clear up
Remain but localised to hands provoked by irritants
Remain as generalised low-grade eczema
Remain confined to flexures
Which organisms can readily infect eczematous skin?
Staph Areus and Streptococcus
S. aureus releases toxins that exacerbate eczema
What clinical features may indicate a food allergy as a cause of eczema?
FTT
Colic pain
Vomiting
Altered bowel habit
What testing may be done in suspected irritant/contact dermatitis?
Skin prick test will identify allergens (can also do RAST test which will identify food and other allergens that will cause anaphylaxis)
How is atopic eczema treated?
Lifestyle:
Avoid triggers - soap and biological agents, wool and nylon clothes (try to wear 100% cotton)
Avoid cold weather or excessive central heating
Avoid scratching and cut nails (may require mittens for infants)
Antihitamines will lower the scratch threshold
Emolients - apply liberally (handful) of Diprobase BD
Steroids:
1% hydrocortisone can be used daily BD
Stronger steroids can be used for flare-ups but avoid using routinely and on the face because it can thin skin
Immunomodulators (e.g. Pimecrolimus) can be used if eczema is not controlled by steroids n children >2yrs
Complications of eczema?
Infection - S aureus or strep - treat with topical abx and hydrocortisone
Herpes virus –> Eczema herpeticum - treat with systemic aciclovir
What is impetigo?
A highly infectious skin infection (s. aureus or strep) common in infants/young children and more prevalent with underlying disease such as eczema
What is the progression of symptoms in impetigo?
Erythmatous macules –> vesicles (–> bulli) –> bursting–> characteristic golden/honey crust and red dirty coloured lesions
What is the treatment for impetigo?
Mild can be treated with topical abx (muciporin)
Moderate-severe cases = flucloxacillin or erythromycin
Avoid school and any close contacts
Can eradicate nasal carriage of pathogen via nasal muciporin cream
Complications of impetigo?
Staphylococcal Scalded Skin Syndrome (SSSS) - widespread desquamation
Acute glomerulo-nephritis (strep)
Common causes of napkin rash?
Irritant (contact) dermatitis - spares skin folds
Infantile Seborrhoeic dermatitis
Candida - well demarcated, in skin folds
Atopic eczema
irritant effect of urine/faeces on babyes buttocks, perineum and thighs - may occur despite good hygiene
Risk factors for nappy rash?
Non-disposable nappies (disposable are more absorbant) Poor hygiene Diarrhoea Immunodeficiency Atopy Irritant soaps/detergents
Symptoms of nappy rash?
Red erythematous region in thighs, buttocks and perineum (flexures usually spared)
Candida –> mucosal white lesions and eyrthema +/-satellite lesions
Management of nappy rash?
Regular nappy changes (6-12 a day)
Thourough cleaning with water
Naked, nappy free time
Barrier creams - zinc
Mild = emollient e.g. diprobase
Moderate-severe = topical steroids (hydrocortisone 1% BD)
Candida infection = antifungal (clotrimazole, micinazole)
Bacterial infection - fusidic acid
What is steven Johnnson Syndrome?
A widspread skin reaction to either a drug (70% -
penecillin, allopurinol, carbamazepine) or infection (Herpes, EBV)
–> eyrthema –> macules/papules –> blisters + bulli
+ haemorrhagic crusting of mucous membranes (lips and eyes - conjunctivitis, uveitis, corneal ulceration)
+/- purpura if severe
Associated with fever, N+V and diarrhoea
Life threatening - 10% mortality, 50% long term sequela
V. rare (3/1 million in EU each year)
Management of Steven Johnson Syndrome?
ABCDE
Supportive for burns - fluids, protect airway Identify cause and remove/treat Emolient ointment Systemic steroids Abx for concomitant infection
What is Niloskys sign?
Steven Johnson syndrome - rub skin - seperates epidermo-dermal jucntion (i.e. top of skin comes off)
How long is the incubation period for scabies?
2-6 weeks
Where might lesions appear on an infant with scabies?
Soles, palms and trunk
Where might lesions appear on an older child with scabies?
Axilla
Hands, flexures of wrists and feet
Belt line and around nipples
Penis and buttocks
Diagnosis of scabies?
Burrow = pathognomonic
+/- papules and vesicles
If burrows unclear - look at skin scrapings under microscope for mites, eggs and mite faeces
Management of scabies?
TREAT WHOLE FAMILY
Anti-parasitic cream - Permethrin 5% - apply from neck down and remove after 8 hours
What is erythema nodosum?
Inflammation of the subcutaneous fat –> hot, red, swollen lesions 2-6cm diameter
Usually last 6 weeks (can be as long as 6 months)
Caused by: Infection: strep, TB Systemic disease: IBD, sarcoidosis malignancy Drugs: penicillins, COCP Pregnancy
Where does erythema nodosum typically occur?
Shins
Can also affect the arms and trunk
Investigations for erythema nodosum?
Bloods - FBC, ESR, LFT Throat swab for strep Pregnancy test Stool sample Imaging - colonoscopy, CXR
