Dermatology

Question 1

What type of eczema is the most common?

Answer 1

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)

Question 2

How does the clinical presentation change with age?

Answer 2

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

Question 3

Which organisms can readily infect eczematous skin?

Answer 3

Staph Areus and Streptococcus

S. aureus releases toxins that exacerbate eczema

Question 4

What clinical features may indicate a food allergy as a cause of eczema?

Answer 4

FTT
Colic pain
Vomiting
Altered bowel habit

Question 5

What testing may be done in suspected irritant/contact dermatitis?

Answer 5

Skin prick test will identify allergens (can also do RAST test which will identify food and other allergens that will cause anaphylaxis)

Question 6

How is atopic eczema treated?

Answer 6

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

Question 7

Complications of eczema?

Answer 7

Infection - S aureus or strep - treat with topical abx and hydrocortisone

Herpes virus –> Eczema herpeticum - treat with systemic aciclovir

Question 8

What is impetigo?

Answer 8

A highly infectious skin infection (s. aureus or strep) common in infants/young children and more prevalent with underlying disease such as eczema

Question 9

What is the progression of symptoms in impetigo?

Answer 9

Erythmatous macules –> vesicles (–> bulli) –> bursting–> characteristic golden/honey crust and red dirty coloured lesions

Question 10

What is the treatment for impetigo?

Answer 10

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

Question 11

Complications of impetigo?

Answer 11

Staphylococcal Scalded Skin Syndrome (SSSS) - widespread desquamation

Acute glomerulo-nephritis (strep)

Question 12

Common causes of napkin rash?

Answer 12

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

Question 13

Risk factors for nappy rash?

Answer 13

Non-disposable nappies (disposable are more absorbant)
Poor hygiene
Diarrhoea
Immunodeficiency
Atopy
Irritant soaps/detergents

Question 14

Symptoms of nappy rash?

Answer 14

Red erythematous region in thighs, buttocks and perineum (flexures usually spared)

Candida –> mucosal white lesions and eyrthema +/-satellite lesions

Question 15

Management of nappy rash?

Answer 15

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

Question 16

What is steven Johnnson Syndrome?

Answer 16

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)

Question 17

Management of Steven Johnson Syndrome?

Answer 17

ABCDE

Supportive for burns - fluids, protect airway
Identify cause and remove/treat
Emolient ointment 
Systemic steroids
Abx for concomitant infection

Question 18

What is Niloskys sign?

Answer 18

Steven Johnson syndrome - rub skin - seperates epidermo-dermal jucntion (i.e. top of skin comes off)

Question 19

How long is the incubation period for scabies?

Answer 19

2-6 weeks

Question 20

Where might lesions appear on an infant with scabies?

Answer 20

Soles, palms and trunk

Question 21

Where might lesions appear on an older child with scabies?

Answer 21

Axilla
Hands, flexures of wrists and feet
Belt line and around nipples
Penis and buttocks

Question 22

Diagnosis of scabies?

Answer 22

Burrow = pathognomonic
+/- papules and vesicles

If burrows unclear - look at skin scrapings under microscope for mites, eggs and mite faeces

Question 23

Management of scabies?

Answer 23

TREAT WHOLE FAMILY

Anti-parasitic cream - Permethrin 5% - apply from neck down and remove after 8 hours

Question 24

What is erythema nodosum?

Answer 24

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

Question 25

Where does erythema nodosum typically occur?

Answer 25

Shins

Can also affect the arms and trunk

Question 26

Investigations for erythema nodosum?

Answer 26

Bloods - FBC, ESR, LFT
Throat swab for strep
Pregnancy test
Stool sample
Imaging - colonoscopy, CXR