Paeds - Derm

Question 1

What is this?

Answer 1

Acne Vulgaris

• caused by chronic inflammation (+/- local infection) in pockets within the skin known as pilosebaeceous units
  
  • pilosebaceous units are the tiny dimples that contain hair follicles and sebaceous glands
  • sebaceous glands produce sebum
• Acne results from increased sebum production, which traps keratin (dead skin cells) and blocks the pilosebaceous unit
  
  • results in swelling and inflammation of the pilosebaceous unit
  • swollen/inflamed units = comedones
• Increased sebum production is due to androgenic hormones (which is why acne is exacerbated by puberty and improves with anti-androgenic hormonal contraception)
• Common acne bacteria = Propionibacterium acnes

Question 2

Describe the presentation of acne vulgaris

Answer 2

• red inflamed sore spots on the skin

Some derm vocab…

• macules = flat marks on the skin
• papules = small lumps on skin
• pustules = small pus filled lumps on skin
• comedomes = skin coloured papules (blocked pilosebaceous units)
• blackheads = open comedones with central black pigmentation
• ice pick scars = small indents in the skin that remain after acne lesions heal
• hypertorphic scars = small lumps in skin that remain after acne lesions heal
• rolling scars = irregular wave like irregularities in the skin that remain after acne lesions heal

Question 3

How would you manage acne vulgaris?

Answer 3

• explore psychosocial burden/ potential associated anxiety or depression

Stepwise medications…

• Mild = no treatment
• Topical benzoyl peroxide = reduces inflammation, is toxic to P.acnes
• Topical retinoids = reduces sebum production
• Topical antibiotics eg. clindamycin (co-prescribe with benzoyl peroxide to reduce bac resistance)
• Oral antibiotics eg. lymecycline
• Oral contraceptive pill = reduces sebum production
  
  • Co-cyprindiol (Dianette) is most effective but has high VTE risk so do not prescribe long term
• Oral retinoids eg. isotretinoin for SEVERE acne
  
  • highly teratogenic (need reliable contraception)
  • SE = photosensitivity of skin to sunlight, suicidal ideation, dry skin/lips, depression, aggression, anxiety, stevens-johnson syndrome and toxic epidermal necrolysis are rare.

Question 4

What is eczema?

Answer 4

• a chronic atopic condition caused by defects in the normal continuity of the skin barrier
  
  • tiny gaps in the skin barrier allow irritants, microbes, allergens to enter and cause an immune response
  • cause inflammation and symptoms.
• presents in infancy with dry, red, itchy, sore patches of skin over flexor surfaces and on the face and neck
• periods where eczema is not controlled = flares

Question 5

How would you manage eczema?

Answer 5

Maintenance

• use emollients to create an artificial barrier over the skin to compensate for the defective skin barrier
• avoid activities that break down the skin barrier like bathing in hot water, scratching at skin, or using drying soaps that remove natural oils (you can use soap substitutes)
• Identify and avoid triggers eg. environmental, dietary, cleaning products, emotional stressors

Flares

• thicker emollients (can apply via “wet wraps” to keep moisture locked in overnight)
• topical steroids (start weak and short term)
  
  • Mild = hydrocortisone, then eumovate (clobetasone butyrate), then betnovate (betamethasone), then very potent = dermovate (clobetasol propionate)
  • SE = thinning of the skin, telangiectasia
• treat complications such as bacterial or viral infections
  
  • most common = Staph aureus, use oral fluclox
• rarely IV antibiotics or oral steroids for severe flares
• other specialist treatments for severe eczema:
  
  • zinc impregnated bandages, topical tacrolimus, phototherapy, systemic immunosuppressants (oral corticosteroids, methotrexate, azathioprine)

Question 6

What is this?

Answer 6

Eczema herpeticum

• a viral skin infection caused by Herpes Simplex Virus (HSV) or Varicella Zoster Virus (VZV)
• typically cocurs in patients with pre-existing skin conditions like eczema or dermatitis, where virus can enter the damaged skin and cause infection
• a widespread, painful and sometimes itchy, erythematous rash
• vesicular rash (involves vesicles containing pus)
  
  • when the vesicles burst, they leave small punched out ulcers with a red base
• usually present with systemic symptoms = fever, lethargy, irritability, reduced oral intake
• usually present with Lymphadenopathy

Question 7

How would you manage Eczema Herpeticum

Answer 7

• confirm diagnosis with viral swabs of the vesicles
• treat with Aciclovir (mild-mod = oral, severe = iv)

Question 8

What is this?

Answer 8

Erythema Nodosum

• a condition where red, inflamed, subcutaneous nodules (lumps) appear across the patient’s shins
  
  • ​nodules are raised, can be painful and tender
• caused by inflammation of the subcutaneous fat in the shins
  
  • inflammation of fat = panniculitis
  • it is caused by a hypersensitivity reaction

Question 9

Erythema nodosum is caused by a hypersensitivity reaction. What are some triggers and chronic diseases it is associated with?

Answer 9

Associated triggers…

• Streptococcal throat infections
• Gastroenteritis
• Mycoplasma pneumoniae
• Tuberculosis
• Pregnancy
• Medications eg. oral contraceptive pill, NSAIDs

Chronic diseases…

• IBD
• Sarcoidosis
• Lymphoma
• Leukaemia

Question 10

How would you investigate and manage erythema nodosum?

Answer 10

• inflammatory markers (CRP, ESR)
• Throat swab for streptococcal infection
• CXR to identify mycoplasma, TB, sarcoidosis, lymphoma
• Stool microscopy and culture for campylobacter and salmonella
• Faecal calprotectin for IBD

Management = treat underlying cause.

Rest, analgesia, steroids can help settle the inflammation.

Most cases fully resolve within 6 weeks.

Question 11

What is this?

Answer 11

Erythema Multiforme

• a widespread, itchy, erythematous rash caused by hypersensitivity reaction
  
  • characteristic “target lesions”
  • does not usually affect mucous membranes but can cause a sore mouth (stomatitis)
• Can be associated with other symptoms = mild fever, stomatitis, muscle and joint aches, headaches, flu like symptoms
• most common causes are viral infections and medications
  
  • associated with Herpes Simplex Virus and Mycoplasma Pneumonia

Question 12

How would you manage erythema multiforme?

Answer 12

• identify the underlying cause
  
  • eg. CXR for mycoplasma pneumonia
• Mild = resolves spontaneously within 1-4 weeks
• Severe eg. affects oral mucosa = admit
  
  • IV fluids, analgesia, steroids
  • antibiotics/ antivirals where infection is present

Question 13

What is this?

Answer 13

Impetigo

• superficial bacterial skin infection
  
  • caused by bacteria entering a break in the skin
• usually caused by Staphylococcus aureus
  
  • presents with characteristic “golden crust”
• less commonly caused by Streptococcus pyogenes
• contagious, so children should stay home from school
• Impetigo is split into non-bulous and bullous

Question 14

Describe non-bullous impetigo

Answer 14

Non-Bullous

• typically occurs around nose or mouth
• exudate from the lesions dry to form a “golden crust”
  
  • ugly, but usually no systemic symptoms, patient is not generally unwell.
• Treat local non-bullous impetigo with Topical fusidic acid
  
  • new guidelines suggest hydrogen peroxide 1% antiseptic cream instead as 1st line
  • Severe or widespread = oral flucloxacillin
• Avoid spread = do not touch lesions, hand hygiene, avoid sharing cutlery or face towels, off school until lesions have healed or antibiotics for atleast 48 hours

Question 15

Describe bullous impetigo

Answer 15

Bullous Impetigo

• always caused by Staph aureus
  
  • it produces epidermolytic toxins that break down skin and cause 1-2cm fluid filled vesicles to form on the skin
  • vesicles grow and burst to form a “golden crust”
• lesions are painful and itchy
• most common in neonates and kids<2 years old
• patients can develop systemic symptoms eg. fever
• Severe infections where lesions are widespread = Staphylococcus scalded skin syndrome
• Confirm diagnosis using swabs of vesicles
• Treatment = antibiotics eg. flucloxacillin
• very contagious to avoid spread

Question 16

What is this?

Answer 16

Cradle cap (seborrhoeic dermatitis)

• infantile seborrhoeic dermatitis can cause a crusted flaky scalp
• Self limiting (usually resolves by 4 months of age)
• seborrhoeic dermatitis = inflammatory skin condition that affects sebaceous glands
  
  • areas that have lots of sebaceous glands eg. scalp, nasolabial folds, eyebrows are the most affected
  • results in erythema, dermatitis, crusted dry skin
  • Malassezia yeast colonisation is associated with it

Question 17

How would you manage cradle cap?

Answer 17

1st line = apply baby oil, vegetable oil or olive oil

• gently brush on the scalp then wash it off

2nd line = white petroleum jelly

• use overnight to soften crusted areas before washing off in the morning

3rd line = topical anti-fungal cream eg. clotrimazole or miconazole for up to 4 weeks

4th line = refer to dermatologist

Question 18

What is nappy rash?

Answer 18

• contact dermatitis in the nappy area
• Sore, red, inflamed skin in the nappy area
  
  • only appears on areas of skin that come in contact with the nappy
  • skin creases are typically spared
  • sometimes red papules can be seen
  • rash is uncomfortable, itchy, infant may appear distressed
• caused by friction between skin and nappy, and contact with urine and faeces in a dirty nappy
• increased risk if delayed changing of nappies, irritant soap products or vigorous cleaning, poorly absorbent nappies, pre-term infants
• most common between 9-12 months of age

Question 19

The breakdown in skin and warm moist environment in the nappy can also predispose to infection with candida or bacteria (usually staphylococcus or streptococcus).

When would you suspect candidal infection instead of a simple nappy rash?

Answer 19

• rash extends into skin folds
• large red macules
• well demarcated scaly border
• circular pattern to the rash spreading outwards, like ringworm
• satellite lesions (small similar patches of rash/pustules near the main rash)
• Oral thrush (white coating on the tongue) is likely to indicate a fungal infection in the nappy area

Question 20

How would you manage nappy rash?

Answer 20

• switch to highly absorbent nappies (disposable gel matrix nappies)
• change the nappy and clean skin asap after wetting or soiling
• use water or gentle alcohol free products to clean nappy area
• ensure nappy area is dry before replacing nappy
• maximise time not wearing nappy
• Candida infection = anti-fungal cream eg. clotrimazole cream or miconazole
• Bacterial infection = antibiotic eg. fuscidic acid cream or oral flucloxacillin

Question 21

What is this?

Answer 21

Psoriasis

• a chronic autoimmune condition that causes recurrent psoriatic skin lesions
  
  • dry, flaky, scaly, sometimes erythematous skin lesions
  • appear in raised, rough plaques
  • commonly over extensor surfaces of elbows and knees, scalp

Question 22

What is Guttate psoriasis?

Answer 22

Guttate psoriasis is the type of psoriasis that commonly occurs in kids

• many small raised erythematous scaly papules across trunk and limbs that eventually turn into plaques
• often triggered by streptococcal throat infection, stress or medications
• often resolves spontaneously within 3-4 months

Question 23

What are 3 specific signs suggestive of psoriasis?

Answer 23

• Auspitz sign = small points of bleeding when plaques are scraped off
• Koebner phenomenon = development of psoriatic lesions to areas of skin affected by trauma
• Residual pigmentation of skin after lesions resolve

Question 24

How would you manage psoriasis?

Answer 24

• assess for need for psychosocial support
• Medications…
  
  • topical steroids
  • topical vitamin D analogues (calcipotriol)
  • topical dithranol
  • topical calcineurin inhibitors (tacrolimus) = typically only used in adults though
  • phototherapy with narrow band UV B light = typically used in extensive guttate psoriasis
• if topical medications are insufficient, systemic treatment can be started by a specialist
  
  • eg. methotrexate, cyclosporine, retinoids, etc.

Question 25

What are non-blanching rashes?

Answer 25

• they are caused by bleeding under the skin
• Petechiae = small <3mm non blanching red spots caused by burst capillaries
• Purpura = larger 3-10mm non-blanching red-purple macules or papules caused by blood leaking from vessels under the skin

Question 26

What kind of differentials would you consider when seeing a non blanching rash?

Answer 26

• Meningococcal septicaemia or other bacterial sepsis
  
  • esp in a feverish unwell child
  • immediate antibiotics and emergency management if meningooccal septicaemia is suspected
• Henoch-Schonlein purpura (HSP)
  
  • purpuric rash on legs and buttocks
  • associated abdo or joint pain
• Idiopathic thrombocytopenic purpura (ITP)
• Acute leukaemias
  
  • gradual development of petechiae
  • associated anaemia, lymphadenopathy, hepatosplenomegaly
• Haemolytic Uraemic Syndrome (HUS)
  
  • associated oligouria and anaemia and recent diarrhoea
• Mechanical
  
  • strong coughing, vomiting or breath holding can cause petechiae in a “superior vena cava distribution” around the eyes and above the neck
• Traumatic petechiae due to tight pressure on the skin
• Viral illness eg. influenza and enterovirus

Question 27

How would you investigate non blanching rashes?

Answer 27

• FBC
  
  • anaemia suggests HUS or leukaemia
  • low WCC suggests neutropenic sepsis or leukaemia
  • low platelets suggests ITP or HUS
• U&Es
  
  • high urea and creatinine suggests HUS or HSP with renal involvement
• CRP and ESR for inflammation/infection
• Coagulation screen for clotting abnormalities
• Blood cultures = sepsis
• Meningococcal PCR to confirm meningococcal disease (do not delay treatment for this)
• LP = meningitis or encephalitis
• Blood pressure
  
  • HTN can occur in HSp and HUS
  • hypotension can occur in septic shock
• Urine dipstick
  
  • proteinuria and haematuria can suggest HSP with renal invovlement, or HUS

Question 28

Differentiate between the rashes of…

• Meningitis
• Parvovirus B19
• Hand foot mouth
• Scarlet fever
• Measles
• Chicken pox
• Roseola (Human Herpes Virus 6)
• Rubella

Answer 28

Meningitis =

• rapidly developing, non blanching purpuric rash
• lethargy, headache, fever, rigors, vomiting
• Give immediate IM Ben Pen

Slapped cheek syndrome (parvo b19) =

• rash on both cheeks, fever

Hand foot mouth (Coxsackie a6) =

• blisters on hands, feet, ulcerations on tongue, fever

Scarlet fever =

• course sand paper red rash, bright red tongue, sore throat, headache, fever
• give phenoxymethylpenicillin for 10 days

Measles =

• erythematous blanching maculopapular rash
• preceded by fever, cough, runny nose, conjunctivitis, grey spots (Kopliks spots) inside cheeks

Chicken pox (varicella zoster)=

• maculopapular vesicular rash that crusts and forms itchy blisters

Roseola infantum (human herpes virus 6)

• lace like red rash across body, high fever for days
• Nagayama spots = papular enanthem on the uvula and soft palate
• febrile convulsions occur in 10-15%
• diarrhoea and cough also seen

Rubella

• postauricular lymphadenopathy, rash that starts on head and spreads to trunk

Question 29

What is that and what symptoms would you expect?

Answer 29

Henoch Schonlein purpura

you would expect a triad of:

• arthralgia
• purpura on extensor surfaces
• abdo pain

Do a urine dip to establish renal involvement as igA immune complexes can deposit in the kidneys and cause haematuria and proteinuria