Xeroderma pigmentosa

Definition

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.

Symptoms

• A sunburn that 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

• Clouding of the cornea
• Keratitis
• Lid tumors
• Blepharitis

The following tests can help diagnose the disorder before birth:

• Amniocentesis
• Chorionic villous sampling
• Culture of amniotic cells

The following tests can help diagnose the disorder after the 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 )

Treatment

Children with this condition require total protection from sunlight. In addition, light coming through window glass and light from fluorescent bulbs is also dangerous. When some sunlight exposure cannot be avoided, protective clothing should cover the skin.

High protection (SPF 30 or greater) sunscreen and very dark, UV-protected glasses should be worn. Trials of medications to help prevent skin cancers are currently being performed.

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