Specific entities in paediatric skin
Aplasia cutis congenita
Background
Well circumscribed ulcer at birth
Familial cases reported, looks to be AD (no gene identified)
1-3cms, round to oval, sharply demarcated and hairless
3:10,000 births
Single lesion in 75%
80% scalp, usually midline
Histo
Absence of adenexal structures
Dermal fibrosis
Flat epidermis
Variable decrease in elastic fibres
Ddx
Trauma, can't differentiate histologically
Cutis laxa
Background
Loose inelastic skin affecting whole body
2 types; 1 is more severe
Extremely rare
Also hoarse voice, emphysema
Congenital and acquired forms
Acquired appears immunologically mediated
Histo
Remaining fibres short and irregular
Can have inflammation in the aquired form
Loss of fine elastic fibres in papillary dermis
EM shows abnormal elastic fibres
Focal dermal hypoplasia (Goltz)
Background
Hx of miscarriage/STB in male fetuses suggests male lethality
Linear cutaneous atrophy with telangiectasia and pigmentation
X linked dominant
Other abnormalities inc syndactly, polydactly, lobster claw hands, dental abnormalities
Rare
Histo
Early - thinning of epidermis with fat around dermal vessels
Later - thinning of dermis with fat in papillary dermis
Late - fat nodules separated from epidermis by few collagen fibres only
Restrictive dermatopathy
Background
Thin shiny skin
Arthygryposis, restricted respiratory effort
Autsomal recessive Lamin A deficiency
Death in hours to weeks
Histo
Decreased or absent elastin
Bundles of collagen parallel to skin
Marked thinning of dermis
EM: disordered collagen bundles and abnormal elastin
Poikiloderma congenita
Background
Rothmund-Thomson = poikiloderma, cataracts, saddle nose, sparse hair and short stature
Hyper and hypopigmentation with telangiectasia and skin thinning
Histo
A/w osteosarcoma
Epidermal atrophy
Vasodilation
Hyperkeratosis
Pigment incontinence
Fragmented elastin
Loss of appendages
Icthyoses
Many types, mostly heritable
Skin scaling
Most show thickened stratum corneum +/-epidermal hyperplasia and dermal inflammation
Consider Oil Red O for neutral lipid storage disease
Alcohol dehydrogenase for Sjogren-Larsson syndrome
EM
Hair sample for ?Nethertons
Icthyosis, spastic paresis and mental retardation
Middle eastern countries, hepatomegaly and neuro impairment
Trichorrhexis invaginata