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