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Chapter: Medicine Study Notes : Skin

Other Skin Lesions

Erythema Multiforme : Confusion/overlap between Erythema Multiforme (EM), Stephens Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) [Later two at the severe end of the spectrum]

Other Skin Lesions


Erythema Multiforme


·        Confusion/overlap between Erythema Multiforme (EM), Stephens Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) [Later two at the severe end of the spectrum]

·        Varying degrees of mucosal involvement and rash 

·        Typical lesion: target lesion – dull red macule or maculopapule 1 – 2 cm across, erythematous rim with cyanotic or purpuric centre. May be blistering. Typically affects acral areas (dorsal hands, feet, palms, soles, forearms, legs). Usually crop over a couple of days and fade after a couple of weeks. 

·        Trunk only in extensive reactions. Also if severe: erosions, haemorrhagic crusting, lesions uncomfortable (not usually painful). May affect cornea. May get systemic upset (fever, anaemia, etc)

·        Histology: vacuolar degeneration of lower epidermis

·        Provoking factors: 

o   HSV – major cause. Rash worst at periphery (+/- oral mucosa). Will get it with subsequent outbreaks as well. History: Do you get cold sores?

o   Mycoplasma (<1% of EM) 

o   Drug reactions – more likely if severe outbreak. Not typical targets (eg red blotches), on trunk as well as acral, may be blistered. Implicated drugs: anticonvulsants, sulphonamides, NSAIDs, allopurinol. Stops drugs if at all possible. Treat like a burn. Steroids controversial 

o   Idiopathic


Erythema Nodosum


·        Lesions: 2 –4 cm, erythematous, tender, especially on shins but also on thighs or forearms. A little raised. Look like purplish bruises

·        Number from 2 – 50 (usually 5 – 6), erupt over 10 days and subside over 3 – 6 weeks

·        Regress with bruise like yellow/green colour changes

·        Systemic signs: fever, generalised aching and malaise

·        Due to deposition of immune complexes in and around venules in the deep dermis

·        Causes:

o   Kids: Streptococcal infection

o   Sarcoidosis (rare in kids)

o   TB

o   Cat scratch disease

o   Yersinia

o   Some drugs

·        Differential:

o  Nodular vasculitis (tend to ulcerated, don‟t heal with bruise like changes)

o  Meningococcal or gonococcal septicaemia (smaller lesions, often purpura, ill patient)


Erythema Toxicum Neonatorum


·        Up to 50% of full term infants (less if preterm), occur up to 4th day

·        Erythematous macules, wheals, papules and pustules – few to several hundred

·        Face, buttocks, torso, proximal limbs, not palms or soles

·        Usually resolve in several days

·        Cause unknown

·        Differential: HSV




·        = Hives or welts.  Intensely itchy.

·        Relationship to allergy and atopy:

o  More likely in atopy 

o  50% related to allergy – type 1 only Þ exposure 15 – 30 minutes prior to onset and last < 24 hoursÞ careful history 

o  Allergy likely to be all over, and no further outbreak for weeks/months

o  Most chronic urticaria is non allergic 

o  Some foods/drugs may cause urticaria without immune involvement (ie histamine release without IgE involvement) 

·        Common causes:

o  Idiopathic – common

o  IgE mediated:

§  Food: peanuts, strawberries, milk, eggs

§  Animal dander: horses, cats

§  Physical: pressure, cold, heat

o  Complement mediated: hereditary angioedema and blood transfusion reactions

o  Mast cell releasing agents: opiates, penicillins

o  Prostacyclin inhibitors: Aspirin, NSAIDs

o  Infections: cause of 80% of acute childhood urticaria (eg hepatitis) 

o  Serum sickness: type 3 reaction. Drugs, especially penicillin. Fever, raised ESR, starts within 5 – 20 days of exposure and lasts 5 – 28 days.


Papular Urticaria


·        Hypersensitivity to an insect 

·        Itchy, urticarial weal ® firm itchy papule

·        Usually gone in a day to two, may persist for months

·        Grouped in clusters, and develop crops at irregular intervals

·        Treatment: try insect repellent

·        If dark skin, may be post-inflammatory hypopigmentation


Alopecia Areata


·        Circumscribed areas of hair loss but skin normal.

·        Presentations:

o  Often scalp – with a few bald areas 1 – 3 cm

o  Loss of all scalp hair is alopecia totalis

o  Loss of hair at all sites is alopecia universalis

·        Not a diagnosis

·        Autosomal, autoimmune dominant disorder with variable penetrance

·        Duration < 1 year in 50 %, relapse common.  Kids get it worse 

·         Associated with Atopy, Downs, Hashimoto's Disease, Pernicious Anaemia, Addison‟s Disease, Vitiligo

·        Treatments include local steroids, topical minoxidil (antihypertensive), etc

·        Differential diagnosis: all produce circumscribed hair loss, but skin itself is abnormal

o  Fungal infections

o  Anything causing scaring (eg skin cancer)

Keratosis Pilaris


·        Common.  More common in atopics 

·        Small whitish plugs of keratin obstruct the follicle mouth. Usually extensor surfaces. Feels like sandpaper 

·        Variable perifollicular erythema

·        Facial involvement usually resolves in teens.  Elsewhere can persist until middle age

·        Autosomal dominant with variable penetrance

·        Differential: Acne (shouldn‟t feel like sandpaper)

·        Treatment: mild steroids, urea creams, salicylic acid creams, etc


Granuloma Annulare


·        Ring of smooth, firm, skin coloured or slightly purplish papules from 1 – 5 cm. No scaling (cf ring worm which is) or blistering (Þ epidermis fine) 

·        Enlarge centrifugally, with beaded rim gradually flattening until it disappears without trace within 2 years

·        Dorsal surfaces of feet, hands and fingers are the commonest sites

·        Lymphohistiocytic granulomata

·        Mainly children and young adults

·        Can treat with intra-lesional steroids


Lichen Planus


·        Occurs in 30 – 60 year olds. Insidious onset, can be explosive, localised or generalised. In 80% resolves in 18 months

·        Clinically: flat topped papules, discrete or coalescing.  White lines on papules = Wickham's Striae.

·        Can also get annular, hypertrophic, atrophic or even bullous forms. Should linear lesions characteristic. Itch variable. Rash resolves with hyperpigmentation. Can be painful on lips or genitals. 

·        Looks like everything else.  Differential:

o   Plane warts

o   Eczema

o   Drug reaction: gold, quinine, thiazides, etc

o   Treatment: Acitretin, steroids, miscellaneous


Tuberous Sclerosis


·        Disorder of haematoma formation: especially in eye, brain, skin, kidney and heart

·        Skin lesion: 

o   Angiofibromas: appear from 3 – 10, firm, discrete red/brown telangiectatic papules, 1 – 10 mm, cheeks and chin

o   Periungual fibromas: smooth skin coloured excrescences emerging from the nail folds

o   Shagreen patch: skin coloured plaque in lumbosacral region 

o   Oval white macules (Ash-leaf-macules) seen under Woods light. But also similar lesions common in normal kids

·        Classically (but not invariably) seen with epilepsy and mental retardation („zits, fits and nit-twits‟)

·        Autosomal dominant with variable penetrance, 50% are new mutations

·        Prevalence ?1/10,000




·        Look like intradermal naevi but soft

·        Type 1: commonest, 1/3000, Autosomal dominant, 30% new mutations

·        Type 2: 2 or more of:

o   6 or more café-au-lait macules over 5 mm in pre-pubertal patients

o   2 or more neurofibromas

o   Freckling in axillary or inguinal regions

o   Optic glioma

o   Others

·        May lead to short stature, macrocephaly, kyphoscoliosis, intellectual handicap, endocrine problems

·        (precocious puberty, acromegaly, Addison‟s), neuro tumours (optic nerve glioma, astrocytomas), etc

·        NF2: characterised by bilateral acoustic neuromas



·        All genetic

·        Ichthyosis vulgaris: common, usually mild.  Entire skin is scaly.  Controlled with moisturises 

·        Rare sorts: Collodion Baby, Bullous and non-bullous ichthyosiform erythroderma, lamellar ichthyosis, X-linked ichthyosis, Harlequin fetus




·        Inflammatory skin disease involving 90% or more of the body surface.  Don‟t call it Exfoliative

·        Dermatitis – meaning is unclear

·        May have sudden onset over weeks or days.  Scaling varies in degrees.  Itch varies 

·        Well unwell, feel hot or cold even though temperature normal. Hypoalbuminaemia and oedema common

·        Fatal in 20 – 40% due to pneumonia, septicaemia, cardiac failure

·        Cause:

o  Eczema: 40%

o  Psoriasis: 25%

o  Lymphoma, leukaemia: 15%

o  Drug reaction: 10%

o  Unknown: 10% (usually elderly)

·        History usually helpful, histology usually unhelpful 

·        Management: monitor fluid balance, rest, nutrition (shedding lots of protein), Moisturiser, careful use of steroids, methotrexate, etc.


Epidermolysis Bullosa


·        All rare

·        Variety of inherited forms.  An acquired form exists

·        Can be localised or generalised

·        Types:

o  Generalised simple autosomal dominant epidermolysis bullosa

o  Junctional EB

o  Autosomal Recessive Dystrophic EB

o  Autosomal dominant dystrophic EB


Incontinentia Pigmenti


·        X-linked dominant, usually lethal in males

·        Presents within first 2 months

·        Tense bullae on limbs then red nodules or plaques on limbs and trunk

·        Pigmentation ranges in colour from blue-grey to brown


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