Paediatric Dermatology
,
,Summary of skin lesions:
Primary skin lesions (arise de novo in the skin)
• Macule
o A small flat area of altered colour or texture
o Example - freckles, measles, rubella, roseola, café-au-lait macule of tuberous
sclerosis
• Patch
o Larger flat area of altered colour or texture
o Example - depigmented patch of vitiligo
• Papule
o A small raised lesion
o Example - allergic, inflammatory papules of acne
• Maculopapular
o Combination of macules and papules
o Example - measles, scarlet fever, parvovirus B19 (erythema infectiosum, fifth
disease)
• Plaque
o A larger raised lesion
o Example - scaly plaque of psoriasis
• Nodule
o A larger raised lesion with a deeper component (involvement of the dermis or
subcutaneous fat)
o Example - nodular lesion of erythema nodosum
• Vesicle
o A small clear blister
o Example - varicella
• Bulla
o A large clear blister
o Example - skin trauma, bullous impetigo
• Wheal/weal
o A transient raised lesion due to derma oedema
o Example - urticaria (hives)
• Pustule
o A pus containing blister
o Example - acute paronychia
• Purpura
o Bleeding into skin or mucosa. Small areas are petechiae, whereas large areas are
ecchymoses. Do not blanch on pressure
o Example - Meningococcal septicaemia, Henoch-Schnlein purpura, Immune
thrombocytopenia, Disseminated intravascular coagulation (DIC)
Secondary skin lesions (evolve from primary lesions or from scratching of primary lesions by
patient)
• Excoriation
o Stretch mark, loss of epidermis following trauma
o Example - atopic dermatitis (from acute rubbing)
• Lichenification
o Roughening of the skin with accentuation of skin markings
o Example - atopic dermatitis (from chronic rubbing)
• Scales
o Flakes of dead skin
o Example - cradle cap in seborrhoeic dermatitis
• Crust
o Dry mass of exudates consisting of serum, dried blood, scales and pus
o Example - impetigo
, • Scar
o Formation of new fibrous tissue post wound healing
o Example - acne
• Erosion
o Loss of epidermis and dermis (heals with scarring)
o Example - epidermolysis bullosa
• Ulcer
o Loss of epidermis and dermis (heals with scarring)
o Example - ulcerating haemangioma
Skin function
• Protection against chemicals and particles - Horny layer
• Preservation of balanced internal environment: water, electrolytes, macromolecules - Horny
layer
• Protection against ultraviolet radiation - Melanocytes
• Protection against invasion - Langerhans cells (large white cells)
• Shock absorber - Dermis and Subcutaneous fat
• Temperature regulation - Dermal blood vessels
• Insulation - Subcutaneous fat
• Sensation - Nerve fibres, specialised nerve endings, Merkel cells (produce neurosecretory
granules)
• Lubrication - Sebaceous glands
• Protein and Prising - Nails
• Calorie reserve - Subcutaneous fat
• Vitamin D synthesis - Keratinocytes
• Body odour/pheromones - Apocrine sweat glands
• Psychosocial, display - Skin, lips, hair and nails
Skin anatomy
Epidermis:
• Closely packed layers of Keratinocytes (85%) adherent to eachother by desmosomes and
dermis through basal membrane called Lamina densa
• Horny layer consists of dead cells bound by lipid
• 60 day transit time from basal layer to the surface
,
,Summary of skin lesions:
Primary skin lesions (arise de novo in the skin)
• Macule
o A small flat area of altered colour or texture
o Example - freckles, measles, rubella, roseola, café-au-lait macule of tuberous
sclerosis
• Patch
o Larger flat area of altered colour or texture
o Example - depigmented patch of vitiligo
• Papule
o A small raised lesion
o Example - allergic, inflammatory papules of acne
• Maculopapular
o Combination of macules and papules
o Example - measles, scarlet fever, parvovirus B19 (erythema infectiosum, fifth
disease)
• Plaque
o A larger raised lesion
o Example - scaly plaque of psoriasis
• Nodule
o A larger raised lesion with a deeper component (involvement of the dermis or
subcutaneous fat)
o Example - nodular lesion of erythema nodosum
• Vesicle
o A small clear blister
o Example - varicella
• Bulla
o A large clear blister
o Example - skin trauma, bullous impetigo
• Wheal/weal
o A transient raised lesion due to derma oedema
o Example - urticaria (hives)
• Pustule
o A pus containing blister
o Example - acute paronychia
• Purpura
o Bleeding into skin or mucosa. Small areas are petechiae, whereas large areas are
ecchymoses. Do not blanch on pressure
o Example - Meningococcal septicaemia, Henoch-Schnlein purpura, Immune
thrombocytopenia, Disseminated intravascular coagulation (DIC)
Secondary skin lesions (evolve from primary lesions or from scratching of primary lesions by
patient)
• Excoriation
o Stretch mark, loss of epidermis following trauma
o Example - atopic dermatitis (from acute rubbing)
• Lichenification
o Roughening of the skin with accentuation of skin markings
o Example - atopic dermatitis (from chronic rubbing)
• Scales
o Flakes of dead skin
o Example - cradle cap in seborrhoeic dermatitis
• Crust
o Dry mass of exudates consisting of serum, dried blood, scales and pus
o Example - impetigo
, • Scar
o Formation of new fibrous tissue post wound healing
o Example - acne
• Erosion
o Loss of epidermis and dermis (heals with scarring)
o Example - epidermolysis bullosa
• Ulcer
o Loss of epidermis and dermis (heals with scarring)
o Example - ulcerating haemangioma
Skin function
• Protection against chemicals and particles - Horny layer
• Preservation of balanced internal environment: water, electrolytes, macromolecules - Horny
layer
• Protection against ultraviolet radiation - Melanocytes
• Protection against invasion - Langerhans cells (large white cells)
• Shock absorber - Dermis and Subcutaneous fat
• Temperature regulation - Dermal blood vessels
• Insulation - Subcutaneous fat
• Sensation - Nerve fibres, specialised nerve endings, Merkel cells (produce neurosecretory
granules)
• Lubrication - Sebaceous glands
• Protein and Prising - Nails
• Calorie reserve - Subcutaneous fat
• Vitamin D synthesis - Keratinocytes
• Body odour/pheromones - Apocrine sweat glands
• Psychosocial, display - Skin, lips, hair and nails
Skin anatomy
Epidermis:
• Closely packed layers of Keratinocytes (85%) adherent to eachother by desmosomes and
dermis through basal membrane called Lamina densa
• Horny layer consists of dead cells bound by lipid
• 60 day transit time from basal layer to the surface
