Paediatric Dermatology Flashcards
Eczema
Eczema is a chronic atopic condition caused by defects in the normal continuity of the skin barrier, leading to inflammation in the skin. There is a genetic component to eczema and it tends to run in families, however there is no single inheritance pattern. It has significant variation in the severity of the condition. Some patients can have very occasional mild patches that respond well to emollients, where others have large areas of skin that are severely affected and require strong topical steroids or systemic treatments.
Eczema usually presents in infancy with dry, red, itchy and sore patches of skin over the flexor surfaces (the inside of elbows and knees) and on the face and neck. Patients with eczema experience periods where the condition is well controlled and periods where the eczema is more problematic, known as flares.
Pathophysiology
The simplified pathophysiology is that eczema is caused by defects in the barrier that the skin provides. Tiny gaps in the skin barrier provide an entrance for irritants, microbes and allergens that create an immune response, resulting in inflammation and the associated symptoms.
Managing eczema
Management can be thought of as maintenance and management of flares, similar to the management of chronic and acute asthma.
The key to maintenance is to create an artificial barrier over the skin to compensate for the defective skin barrier. This is done using emollients that are as thick and greasy as tolerated, used as often as possible, particularly after washing and before bed. Patients should avoid activities that break down the skin barrier, such as bathing in hot water, scratching or scrubbing their skin and using soaps and body washes that remove the natural oils in the skin. Emollients or specifically designed soap substitutes can be used instead of soap and body washes when showering or washing hands.
Some patients find certain environmental factors play a role in making their eczema symptoms worse or better. For example, it may completely resolve on holiday in warm, humid countries, only to flare on returning to the cold air in the UK. Environmental triggers, such as changes in temperature, certain dietary products, washing powders, cleaning products and emotional events or stresses can also play a role.
Flares can be treated with thicker emollients, topical steroids, “wet wraps” (covering affected areas in a thick emollient and applying a wrap to keep moisture locked in overnight) and treating any complications such as bacterial or viral infections. Very rarely IV antibiotics or oral steroids might be required in very severe flares.
Other specialist treatments in severe eczema include zinc impregnated bandages, topical tacrolimus, phototherapy and systemic immunosuppressants, such as oral corticosteroids, methotrexate and azathioprine.
Emollients for eczema
Depending on the severity of the eczema, some patients may only require thin emollients to maintain their skin barrier, whilst others with more severe eczema require very thick greasy emollients. The general rule is to use emollients that are as thick as tolerated and required to maintain the eczema.
Thin creams:
E45
Diprobase cream
Oilatum cream
Aveeno cream
Cetraben cream
Epaderm cream
Thick, greasy emollients:
50:50 ointment (50% liquid paraffin)
Hydromol ointment
Diprobase ointment
Cetraben ointment
Epaderm ointment
Topical steroids for eczema
The general rule is to use the weakest steroid for the shortest period required to get the skin under control. Steroids are very good for settling down the immune activity in the skin and reducing inflammation, but they do come with side effects. They can lead to thinning of the skin, which in turn make the skin more prone to flares, bruising, tearing, stretch marks and enlarged blood vessels under the surface of the skin called telangiectasia. Depending on the location and strength of the steroid there may be some systemic absorption of the steroid. The risks of using steroids need to be balanced against the risk of poorly controlled eczema.
The thicker the skin, the stronger the steroid required. Only weak steroids used very cautiously should be applied to areas of thin skin such as the face, around the eyes and in the genital region. It is best to completely avoid steroids in these areas in children.
The steroid ladder from weakest to most potent:
Mild: Hydrocortisone 0.5%, 1% and 2.5%
Moderate: Eumovate (clobetasone butyrate 0.05%)
Potent: Betnovate (betamethasone 0.1%)
Very potent: Dermovate (clobetasol propionate 0.05%)
Bacterial infection and eczema
Opportunistic bacterial infection of the skin is common in eczema. The breakdown in the skin’s protective barrier allows an entry point for infective organisms. The most common organism is staphylococcus aureus. Treatment is with oral antibiotics, particularly flucloxacillin. More severe cases may require admission and intravenous antibiotics.
Eczema Herpeticum
Eczema herpeticum is a viral skin infection caused by the herpes simplex virus (HSV) or varicella zoster virus (VZV). It was previously known as Kaposi varicelliform eruption (don’t confuse this with Kaposi sarcoma, which occurs in late stage HIV). Herpes simplex virus 1 (HSV-1) is the most common causative organism, and may be associated with a coldsore in the patient or a close contact. It usually occurs in a patient with a pre-existing skin condition, such as atopic eczema or dermatitis, where the virus is able to enter the skin and cause an infection.
Presentation of eczema herpeticum
A typical presentation is a patient who suffers with eczema that has developed a widespread, painful, vesicular rash with systemic symptoms such as fever, lethargy, irritability and reduced oral intake. There will usually be lymphadenopathy (swollen lymph nodes).
The Rash
The rash is usually widespread and can affect any area of the body. It is erythematous, painful and sometimes itchy, with vesicles containing pus. The vesicles appear as lots of individual spots containing fluid. After they burst, they leave small punched-out ulcers with a red base.
Managing eczema herpeticum
Viral swabs of the vesicles can be used to confirm the diagnosis, although treatment is usually started based on the clinical appearance.
Treatment is with aciclovir. A mild or moderate case may be treated with oral aciclovir, whereas more severe cases may require IV aciclovir.
Complications of eczema herpeticum
Children with eczema herpeticum can be very unwell. When not treated adequately it can be a life threatening condition, particularly in patients that are immunocompromised.
Bacterial superinfection can occur, leading to a more severe illness. This needs treatment with antibiotics.
Psoriasis
Psoriasis is a chronic autoimmune condition that causes recurrent symptoms of psoriatic skin lesions. There is a large variation in how severely patients are affected with psoriasis. There appears to be a genetic component but no clear genetic inheritance has been established. Around a third of patients have a first degree relative with psoriasis. The symptoms start in childhood in a third of patients.
Patches of psoriasis are dry, flaky, scaly, faintly erythematous skin lesions that appear in raised and rough plaques, commonly over the extensor surfaces of the elbows and knees and on the scalp. These skin changes are caused by the rapid generation of new skin cells, resulting in an abnormal buildup and thickening of the skin in those areas.
Types of Psoriasis
Plaque psoriasis features the thickened erythematous plaques with silver scales, commonly seen on the extensor surfaces and scalp. The plaques are 1cm – 10cm in diameter. This is the most common form of psoriasis in adults.
Guttate psoriasis is the second most common form of psoriasis and commonly occurs in children. It presents with many small raised papules across the trunk and limbs. The papules are mildly erythematous and can be slightly scaly. Over time the papules in guttate psoriasis can turn into plaques. Guttate psoriasis is often triggered by a streptococcal throat infection, stress or medications. It often resolves spontaneously within 3 – 4 months.
Pustular psoriasis is a rare severe form of psoriasis where pustules form under areas of erythematous skin. The pus in these areas is not infectious. Patients can be systemically unwell. It should be treated as a medical emergency and patients with pustular psoriasis initially require admission to hospital.
Erythrodermic psoriasis is a rare severe form of psoriasis with extensive erythematous inflamed areas covering most of the surface area of the skin. The skin comes away in large patches (exfoliation) resulting in raw exposed areas. It should be treated as a medical emergency and patients require admission.
Presentation of psoriasis
In children the distribution and presentation of psoriasis may differ from adults. Guttate psoriasis is more common in children, often triggered by a throat infection. Plaques of psoriasis are likely to be smaller, softer and less prominent.
There are a few specific signs suggestive of psoriasis:
Auspitz sign refers to small points of bleeding when plaques are scraped off
Koebner phenomenon refers to the development of psoriatic lesions to areas of skin affected by trauma
Residual pigmentation of the skin after the lesions resolve
The diagnosis can be made based on the clinical appearance of the lesions.
Managing psoriasis
Management depends on the severity of the condition. Psoriasis in children is usually managed and followed up by a specialist. It can be difficult to treat and psychosocial support is very important. The treatment options include:
Topical steroids
Topical vitamin D analogues (calcipotriol)
Topical dithranol
Topical calcineurin inhibitors (tacrolimus) are usually only used in adults
Phototherapy with narrow band ultraviolet B light is particularly useful in extensive guttate psoriasis
Rarely, where topical treatments fail with severe and difficult to control psoriasis, children may be started on unlicensed systemic treatment under the guidance of an experienced specialist. This might include methotrexate, cyclosporine, retinoids or biologic medications.
There are two products that contain both a potent steroid and vitamin D analogue that are commonly prescribed and worth being aware of. These not licensed in children and will be guided by a specialist.
Dovobet
Enstilar
Psoriasis associations
Nail psoriasis describes the nail changes that can occur in patients with psoriasis. These include nail pitting, thickening, discolouration, ridging and onycholysis (separation of the nail from the nail bed).
Psoriatic arthritis occurs in 10 – 20% of patients with psoriasis and usually occurs within 10 years of developing the skin changes. It typically affects people in middle age but can occur at any age.
Psychosocial implications of having chronic skin lesions, which may affect mood, self esteem and social acceptance and cause depression and anxiety.
Other co-morbidities that increase the risk of cardiovascular disease are associated with psoriasis, particularly obesity, hyperlipidaemia, hypertension and type 2 diabetes.
Acne vulgaris
Acne vulgaris (acne) is an extremely common condition, often affecting people during puberty and adolescence. Most people are affected at some point during their lives, and symptoms can range from mild to severe.
Pathophysiology
Acne is caused by chronic inflammation, with or without localised infection, in pockets within the skin known as the pilosebaceous unit. The pilosebaceous units are the tiny dimples in the skin that contain the hair follicles and sebaceous glands. The sebaceous glands produce the natural skin oils and a waxy substance known as sebum.
Acne results from increased production of sebum, trapping of keratin (dead skin cells) and blockage of the pilosebaceous unit. This leads to swelling and inflammation in the pilosebaceous unit. Androgenic hormones increase the production of sebum, which is why acne is exacerbated by puberty and improves with anti-androgenic hormonal contraception. Swollen and inflamed units are called comedones.
The Propionibacterium acnes bacteria is felt to play an important role in acne. This is a bacteria that colonises the skin. It is thought that excessive growth of this bacteria can exacerbate acne. Many of the treatments of acne aim to reduce these bacteria.
Presentation of acne
There is significant variation in the severity of acne. It presents with red, inflamed and sore “spots” on the skin, typically distributed across the face, upper chest and upper back.
There are few terms used to describe the appearance of the lesions:
Macules are flat marks on the skin
Papules are small lumps on the skin
Pustules are small lumps containing yellow pus
Comedomes are skin coloured papules representing blocked pilosebaceous units
Blackheads are open comedones with black pigmentation in the centre
Ice pick scars are small indentations in the skin that remain after acne lesions heal
Hypertrophic scars are small lumps in the skin that remain after acne lesions heal
Rolling scars are irregular wave-like irregularities of the skin that remain after acne lesions heal
Managing acne
The aim of treatment is to reduce the symptoms of acne, reduce the risk of scarring and minimise the psychosocial impact of the condition. Always explore the psychosocial burden and any potential anxiety and depression that may be associated with the condition.
Treatment is initiated in a stepwise fashion based on the severity and response to treatment:
No treatment may be acceptable if mild
Topical benzoyl peroxide reduces inflammation, helps unblock the skin and is toxic to the P. acnes bacteria
Topical retinoids (chemicals related to vitamin A) slow the production of sebum (women of childbearing age need effective contraception)
Topical antibiotics such as clindamycin (prescribed with benzoyl peroxide to reduce bacterial resistance)
Oral antibiotics such as lymecycline
Oral contraceptive pill can help female patients stabilise their hormones and slow the production of sebum
Oral retinoids for severe acne (i.e. isotretinoin) is an effective last-line option, although it is only prescribed by a specialist after other methods fail. This needs careful follow-up and monitoring and reliable contraception in females. Retinoids are highly teratogenic.
Co-cyprindiol (Dianette) is the most effective combined contraceptive pill for acne due to it’s anti-androgen effects. It has a higher risk of thromboembolism, so treatment is usually discontinued once acne is controlled and it is not prescribed long term.
Isotretinoin
Oral isotretinoin (Roaccutane) is very effective at clearing the skin. It is a retinoid, and works by reducing production of sebum, reducing inflammation and reducing bacterial growth. It can only be prescribed under expert supervision by a dermatologist. It is strongly teratogenic (harmful to the fetus during pregnancy). Patients need to have effective and reliable contraception and must stop isotretinoin for at least a month before becoming pregnant.
Side effects of isotretinoin include:
Dry skin and lips
Photosensitivity of the skin to sunlight
Depression, anxiety, aggression and suicidal ideation. Patients should be screened for mental health issues prior to starting treatment.
Rarely Stevens-Johnson syndrome and toxic epidermal necrolysis
Viral Exanthemas
An “exanthem” is an eruptive widespread rash. Originally there were six “viral exanthemas” known as first, second, third, fourth, fifth and sixth disease. These have since been renamed as we have learned more about their underlying causes:
First disease: Measles
Second disease: Scarlet Fever
Third disease: Rubella (AKA German Measles)
Fourth disease: Dukes’ Disease
Fifth disease: Parvovirus B19
Sixth disease: Roseola Infantum
Measles
Measles is caused by the measles virus. It is highly contagious via respiratory droplets. Symptoms start 10 – 12 days after exposure, with fever, coryzal symptoms and conjunctivitis.
Koplik spots are greyish white spots on the buccal mucosa. They appear 2 days after the fever. They are pathognomonic for measles, meaning if a patient has Koplik spots, you can diagnose measles.
The rash starts on the face, classically behind the ears, 3 – 5 days after the fever. It then spreads to the rest of the body. The rash is an erythematous, macular rash with flat lesions.
Measles is self resolving after 7 – 10 days of symptoms. Children should be isolated until 4 days after their symptoms resolve. Measles is a notifiable disease and all cases need to be reported to public health. 30% of patients with measles develop a complication.
Complications include:
Pneumonia
Diarrhoea
Dehydration
Encephalitis
Meningitis
Hearing loss
Vision loss
Death
Scarlet Fever
Scarlet fever is associated with group A streptococcus infection, usually tonsillitis. It is not caused by a virus.
Scarlet fever is caused by an exotoxin produced by the streptococcus pyogenes (group A strep) bacteria. It is characterised by a red-pink, blotchy, macular rash with rough “sandpaper” skin that starts on the trunk and spreads outwards. Patients can have red, flushed cheeks.
Other features:
Fever
Lethargy
Flushed face
Sore throat
Strawberry tongue
Cervical lymphadenopathy
Treatment is with antibiotics for the underlying streptococcal bacterial infection. This is with phenoxymethylpenicillin (penicillin V) for 10 days. Scarlet fever is a notifiable disease and all cases need to be reported to public health. Children should be kept off school until 24 hours after starting antibiotics.
Patients can have other conditions associated with group A strep infection:
Post-streptococcal glomerulonephritis
Acute rheumatic fever
Rubella
Rubella is caused by the rubella virus. It is highly contagious and spread by respiratory droplets. Symptoms start 2 weeks after exposure.
It presents with a milder erythematous macular rash compared with measles. The rash starts on the face and spreads to the rest of the body. The rash classically lasts 3 days. It can be associated with a mild fever, joint pain and a sore throat. Patients often have enlarged lymph nodes (lymphadenopathy) behind the ears and at the back of the neck.
Management is supportive and the condition is self limiting. Rubella is a notifiable disease and all cases need to be reported to public health. Children should stay off school for at least 5 days after the rash appears. Children should avoid pregnant women.
Complications are rare but include thrombocytopenia and encephalitis. Rubella is dangerous in pregnancy and can lead to congenital rubella syndrome, which is a triad of deafness, blindness and congenital heart disease.
Duke’s Disease
Duke’s disease, also known as fourth disease, has very interestingly been mostly forgotten and is never used in clinical practice. Even when it was first described as a similar disease to rubella, there was disagreement about whether it actually existed or whether doctors were simply misdiagnosing a different illness. Since viral and bacterial testing has become possible, no organism has been found that could explain a specific “fourth disease”.
It is very common for children to get non-specific “viral rashes”. It is likely that “fourth disease” was used to describe these non-specific viral rashes that are now understood to be caused by many potential viruses.
Parvovirus B19
Parvovirus B19 is also known as fifth disease, slapped cheek syndrome and erythema infectiosum. It is caused by the parvovirus B19 virus.
Parvovirus infection starts with mild fever, coryza and non-specific viral symptoms such as muscle aches and lethargy. After 2 – 5 days the rash appears quite rapidly as a diffuse bright red rash on both cheeks, as though they have “slapped cheeks”. A few days later a reticular mildly erythematous rash affecting the trunk and limbs appears that can be raised and itchy. Reticular means net-like.
The illness is self limiting and the rash and symptoms usually fade over 1 – 2 weeks. Healthy children and adults have a low risk of any complications and are managed supportively with plenty of fluids and simple analgesia. It is infectious prior to the rash forming, but once the rash has formed they are no longer infectious and do not need to stay off school.
Patients that are at risk of complications include immunocompromised patients, pregnant women and patients with haematological conditions such as sickle cell anaemia, thalassaemia, hereditary spherocytosis and haemolytic anaemia. These patients require serology testing for parvovirus to confirm the diagnosis and checking of the full blood count and reticulocyte count for aplastic anaemia. People that would be at risk of complications that have come in contact with someone with parvovirus prior to the rash forming, should be informed and may need investigations.
Complications:
Aplastic anaemia
Encephalitis or meningitis
Pregnancy complications including fetal death
Rarely hepatitis, myocarditis or nephritis
Roseola Infantum
Roseola infantum is also known as just roseola or sixth disease. This is caused by human herpesvirus 6 (HHV-6) and less frequently by human herpesvirus 7 (HHV-7).
Roseola has a typical pattern of illness. It presents 1 – 2 weeks after infection with a high fever (up to 40ºC) that comes on suddenly, lasts for 3 – 5 days and then disappears suddenly. There may be coryzal symptoms, sore throat and swollen lymph nodes during the illness. When the fever settles, the rash appears for 1 – 2 days. The rash consists of a mild erythematous macular rash across the arms, legs, trunk and face and is not itchy.
Children make a full recovery within a week and do not generally need to be kept off nursery if they are well enough to attend.
The main complication to be aware of is febrile convulsions due to high temperature. Immunocompromised patients may be at risk of rare complications such as myocarditis, thrombocytopenia and Guillain-Barre syndrome.
Erythema Multiforme
Erythema multiforme is an erythematous rash caused by a hypersensitivity reaction.
The most common causes are viral infections and medications. It is also notably associated with the herpes simplex virus (causing coldsores) and mycoplasma pneumonia.
Presentation of Erythema Multiforme
Erythema multiforme produces a widespread, itchy, erythematous rash. It produces characteristic “target lesions”. Target lesions are red rings within larger red rings, with the darkest red at the centre, similar to a bulls-eye target. It does not usually affect the mucous membranes but can cause a sore mouth (stomatitis).
The symptoms come on abruptly over a few days. It may be associated with other symptoms of mild fever, stomatitis, muscle and joint aches, headaches and general flu-like symptoms.
Managing Erythema Multiforme
The diagnosis is made clinically based on the appearance of the rash.
It is important to identify the underlying cause. Where there is a clear underlying cause, for example a recent coldsore or treatment with penicillin, it may be managed supportively. Where there is no clear underlying cause it may be worth investigating further, for example doing a chest xray to look for mycoplasma pneumonia.
Most of the time erythema multiforme is mild and resolves spontaneously within one to four weeks without any treatment or lasting effects. Cases may be recurrent, particularly associated with recurrent coldsores.
Severe cases may require admission to hospital, particularly where it affects the oral mucosa. Treatments used in severe cases include IV fluids, analgesia and steroids (systemic or topical). The use of systemic steroids is controversial. Antibiotics or antivirals may be used where infection is present.
Urticaria
Urticaria are also known as hives. They are small itchy lumps that appear on the skin. They may be associated with a patchy erythematous rash. This can be localised to a specific area or widespread. They may be associated with angioedema and flushing of the skin. Urticaria can be classified as acute urticaria or chronic urticaria.
Pathophysiology
Urticaria are caused the release of histamine and other pro-inflammatory chemicals by mast cells in the skin. This may be part of an allergic reaction in acute urticaria or an autoimmune reaction in chronic idiopathic urticaria.
Causes of Acute Urticaria
Acute urticaria is typically triggered by something that stimulates the mast cells to release histamine. This may be:
Allergies to food, medications or animals
Contact with chemicals, latex or stinging nettles
Medications
Viral infections
Insect bites
Dermatographism (rubbing of the skin)
Chronic Urticaria
Chronic urticaria is an autoimmune condition, where autoantibodies target mast cells and trigger them to release histamines and other chemicals. It can be sub-classified depending on the cause:
Chronic idiopathic urticaria
Chronic inducible urticaria
Autoimmune urticaria
Chronic idiopathic urticaria describes recurrent episodes of chronic urticaria without a clear underlying cause or trigger.
Chronic inducible urticaria describes episodes of chronic urticaria that can be induced by certain triggers, such as:
Sunlight
Temperature change
Exercise
Strong emotions
Hot or cold weather
Pressure (dermatographism)
Autoimmune urticaria describes chronic urticaria associated with an underlying autoimmune condition, such as systemic lupus erythematosus.
Managing urticaria
Antihistamines are the main treatment for urticaria. Fexofenadine is usually the antihistamine of choice for chronic urticaria. Oral steroids may be considered as a short course for severe flares.
In very problematic cases referral to a specialist may be required to consider treatment with:
Anti-leukotrienes such as montelukast
Omalizumab, which targets IgE
Cyclosporin
Chickenpox
Chickenpox is caused by the varicella zoster virus (VZV). It causes a highly contagious, generalised vesicular rash. It is common in children. Once a child has had an episode of chickenpox, they develop immunity to the VZV virus and will not be affected again.
Presentation of chickenpox
Chickenpox is characterised by widespread, erythematous, raised, vesicular (fluid filled), blistering lesions. The rash usually starts on the trunk or face and spreads outwards affecting the whole body over 2 – 5 days. Eventually the lesions scab over, at which point they stop being contagious.
Other symptoms:
Fever is often the first symptom
Itch
General fatigue and malaise
Infectivity of chickenpox
Chickenpox is highly contagious and spread through direct contact with the lesions or through infected droplets from a cough or sneeze. Patients become symptomatic 10 days to 3 weeks after exposure. The stop being contagious after all the lesions have crusted over.
Complications of chickenpox
Bacterial superinfection
Dehydration
Conjunctival lesions
Pneumonia
Encephalitis (presenting as ataxia)
After the infection the virus can lie dormant in the sensory dorsal root ganglion cells and cranial nerves reactivate later in life as shingles or Ramsay Hunt syndrome.
