Dermatology Flashcards
At what age does atopic eczema typically present in children?
typically presents before the age of 2
Describe the clinical presentation of eczema
- dry, itchy, erythematous rash
- typical distribution over flexor surfaces, face and neck
- episodic with flares
What is the typical distribution of atopic eczema in infants
Face and trunk
How is eczema managed
- avoid irritants
- maintenance : simple emollients (E45, diprobase)
- flares: thicker emollients (cetraben) or topical steroids (hydrocortisone, beclomethasone)
- wet wrapping - large amounts of emollient applied under wet bandages
Describe the pathophysiology of eczema
- chronic atopic condition caused by defects in the normal continuity of the skin barrier
- Tiny gaps in the skin barrier provide an entrance for irritants, microbes and allergens that create an immune response, leading to inflammation in the skin
What are the categories of steroids used to treat eczema, listed 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%)
What is stevens-Johnson syndrome
disproportional severe immune response causing epidermal sclerosis, resulting in blistering and shedding of the top layer of skin
Give 4 drugs that cause stevens-Johnson syndrome
- anti-epileptics: lamotrigine, carbamazepine, phenytoin
- allopurinol
- NSAIDs
- Abx: penicillin, sulphonamides
Give 4 infections that cause stevens-Johnson syndrome
- herpes simplex
- Mycoplasma pneumonia
- Cytomegalovirus
- HIV
Describe the clinical presentation of stevens-Johnson syndrome
- initially non-specific systemic symptoms: fever, cough, arthralgia
- red/purple maculopapular rash with target lesions that may develop into vesicles
- Nikolsky sign is positive in erythematous areas - blisters and erosions appear when the skin is rubbed gently
- Eyes: conjunctivitis, uveitis, corneal ulceration
- mucosal involvement
How is stevens-Johnson syndrome managed
- medical emergency - hospital admission
- supportive care - nutrition, antiseptics, analgesia and ophthalmology input
- steroids, immunoglobulins and immunosuppressants with specialist guidance
What is the difference between Stevens-Johnson syndrome and toxic epidermal necrolysis
spectrum of the same pathology but SJS generally affects less than 10% of body surface area whereas TEN affects more than 10% of body surface area
What is urticaria
local or generalised superficial swelling of the skin
aka hives
Explain the pathophysiology of urticaria
- Release of histamine and other pro-inflammatory chemicals by mast cells in the skin
- These may be part of an allergic reaction in acute urticaria or an autoimmune reaction in chronic idiopathic urticaria
Describe the clinical presentation of urticaria
- pale, pink raised skin
- pruritic
Give 4 causes of acute urticaria
- allergies to food, animals or meds
- viral infections
- insect bites
- contact with chemicals, latex or stinging nettles
Give 4 drug causes of urticaria
- aspirin
- penicillin
- NSAIDs
- opiates
What is chronic urticaria
- persisting over 6 weeks
- usually non-allergic, an autoimmune condition where autoantibodies target mast cells and trigger them to release histamine and other chemicals
How is acute urticaria managed
- trigger identification and avoidance
- 1st line: non-sedating antihistamines (cetirizine, loratadine) - continued for up to 6 weeks following an episode of acute urticaria
- a sedating antihistamine (e.g. chlorphenamine) may be considered for night-time use
- prednisolone is used for severe or resistant episodes
How is chronic urticaria managed
- trigger identification and avoidance
- 1st: antihistamine +/- LTRA
- 2nd: omalizumab
- short course prednisolone
What is angioedema, and how is it related to urticaria?
Angioedema is swelling in deeper tissues that may occur with urticaria, particularly affecting the lips and soft tissues around the eyes
What age range is nappy rash most common in
9 - 12 months
Give 4 causes of nappy rash
- irritant (contact) dermatitis (mc)
- candida dermatitis
- atopic eczema
- infantile Seborrhoeic dermatitis
What causes irritant dermatitis in nappy rash
due to irritant effect of urinary ammonia and faeces
Give 5 RFs for nappy rash
- delayed changing of nappies
- diarrhoea
- oral antibiotics (predispose to candida)
- irritant soap and vigorous cleaning
- preterm infant
How does contact dermatitis in the nappy area present
- sore, red, inflamed skin
- creases of the groin are characteristically spared
- rash may be itchy and cause infant distress
- severe, long standing rash can lead to erosions and ulcerations
What signs would point to a candida infection rather than simple nappy rash
- rash extending into skin folds (creases)
- large red macules
- satellite lesions
- circular pattern to the rash spreading outwards
How is nappy rash managed
- switch to highly absorbent, disposable nappies
- expose nappy area to air when possible
- antifugal/ antibacterial cream
- mild topical steroids (hydrocortisone) in severe cases
What are petechiae
small (<3mm), non-blanching red spots on the skin caused by burst capillaries
What are purpura
large (3-10mm), non-blanching, red-purple, macules or papules caused by leaking of blood from vessels under the skin
Why should children with a new purpuric rash be admitted immediately for investigations?
may indicate serious conditions such as meningococcal septicaemia or acute lymphoblastic leukaemia, warranting immediate investigation.
What should be done if meningococcal septicaemia is suspected in a child with a purpuric rash in a pre-hospital setting?
IM benzylpenicillin should be administered prior to transfer to ensure timely treatment
Give 3 non-thrombocytopenic differentials of non-blanching rashes in children
- Henoch-Schonlein purpura - rash confined to bum and legs
- meningococcal septicaemia - feverish, unwell child
- trauma - accidental/ NAI
Give 3 thrombocytopenic differentials for non-blanching rashes in children
- Acute lymphoblastic leukaemia - lymphadenopathy and hepatosplenomegaly
- Immune thrombocytopenic purpura - widespread rash in unwell child
- disseminated intravascular coagulation - critically ill
What is a macular rash
A non-palpable (flat) rash with colour changes in limited areas
What is a papular rash
A palpable rash with raised, solid lesions and colour changes in
limited areas
What is a vesicular rash
elevated lesions that are filled with clear fluid less than 0.5cm
