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This rare AR photodermatosis affects all races and has an equal sex incidence (2.3
cases/million live births in Western Europe). Patients develop premature photodamage,
skin cancers, and ocular abnormalities. Thirty percent of patients develop progressive
neurological disorders. The disease is devastating, and cutaneous malignancies cause
early death. Normally, photodamaged DNA is excised and repaired with newly
synthesized DNA (excision repair), but XP cells are unable to repair damaged DNA. The
defect affects all cell types. Patients have an increased risk of cutaneous and ocular
malignancy, as well as malignancy in other tissues, e.g. oral cavity, breast, lung, liver,
gastric, renal, and brain.
Skin is normal at birth, but XP presents within the first few years and has a major impact
on the lifestyle of the child and their family. Clinical features vary, but fair-skinned
children are the most severely affected.

What should I look for?
• Easy sunburn that usually presents within the first 2 years of life.
• UVB-induced erythema that is delayed in onset and peaks in 2–3 days, rather than the
usual 24h.
• A history of blistering or burning after very little sun exposure.
• Photophobia in young children.
• Dryness of sun-exposed skin (xeroderma).
• Irregular freckling appears in the first year of life on exposed skin.
• Scarring of exposed skin.
• Signs of premature photodamage—mottled hyperpigmented patches, hypopigmented
macules, telangiectasia.
• Hyperkeratotic lower lip (solar cheilitis).
• Eyelid freckling, loss of lashes, ectropion, conjunctival telangiectasia, dry eyes, and
corneal damage, leading to visual impairment.
• Solar keratoses (premalignant change).
• Skin cancers develop in all (median onset age 8 years)—BCC, SCC, melanoma.
• Parents with a history of skin cancers, but no other signs of XP.

Management
• The diagnosis is confirmed by skin biopsy and demonstration of the DNA repair defect
in cultured fibroblasts.
• Care should be provided by a multidisciplinary team that may include paediatricians,
dermatologists, ophthalmologists, neurologists, cancer specialist nurses, and plastic
surgeons.
• It is crucial to protect the skin from photodamage to slow the onset of life-threatening
cutaneous malignancies.
• Carers and/or patients should examine the skin regularly for signs of skin cancer.
Cancers are treated surgically.
• Oral retinoids may reduce the incidence of skin cancer.
• Patients should be protected from cigarette smoke.
• Encourage patients to join XP Patient Support group.

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