Definition
Xeroderma pigmentosa is an inherited inability to repair DNA damage from ultraviolet light.

Causes, incidence, and risk factors

Xeroderma pigmentosa is inherited as an autosomal recessive trait. Those affected are extremely sensitive to the ultraviolet portion of sunlight. Ultraviolet light exposure damages DNA (the genetic material within a cell) in skin cells.

Normally, peoples' bodies can repair this damage. However, people with xeroderma pigmentosa cannot repair the damaged DNA and rapidly develop skin atrophy (thinning), splotchy pigmentation, spidery blood vessels in the skin (telangiectasia), and skin cancers.

Skin cancers include basal cell carcinoma, squamous cell carcinoma, and malignant melanoma. Basal cell skin cancers are fairly easy to treat and have a low rate of metastasis. Squamous cell cancer is more difficult to treat, and melanoma has a very high rate of spreading to other organs.

Affected people develop increasing disfigurement following any intermittent exposure to sunlight. Malignant (cancerous) skin lesions are often present before the child is 5 years old.

Prevention
Genetic counseling is recommended for prospective parents with a family history of xeroderma pigmentosa. Intrauterine diagnosis is possible from cultured amniotic cells that exhibit the inability to repair DNA.

Symptoms

A sunburn which does not heal following minimal sun exposure
Blistering following minimal sun exposure
Cutaneous telangiectasia
Increasing irregular pigmentation of the skin
Crusting of the skin
Scaling of the skin
Oozing raw skin surface
Discomfort when exposed to bright light (photophobia)
Neurologic changes are sometimes noted

Signs and tests
There may be a family history of xeroderma pigmentosa.

Examination of the eyes may show other signs of this disorder:

Clouding of the cornea
Keratitis
Lid tumors
Blepharitis

Tests:
Prenatal (before birth) diagnosis:

Amniocentesis
Chorionic villous sampling
Culture of amniotic cells

Postnatal diagnosis (after birth of the child):
Culture of skin fibroblasts
Skin biopsy (of skin tumors confirms the type of tumor, including basal cell carcinoma, squamous cell carcinoma, or malignant melanoma)