Tuberous sclerosis

Alternative names

Definition

Causes, incidence, and risk factors

Tuberous sclerosis is inherited as an autosomal dominant trait (only one parent must pass on the bad gene for the child to get the disease). However, a high percentage of cases are due to new mutations (which occur in the sperm or egg of one of the parents that created the particular child), so there usually is no family history of the disease.

It is one of a group of diseases described as neuro-cutaneous syndromes because of extensive involvement of both the skin and the central nervous system (brain and/or spinal cord). The symptoms of tuberous sclerosis, however, vary considerably from minimally affected people with normal intelligence and no seizures to severely affected people with profound retardation and frequent, difficult-to-control seizures or serious tumors.

Severely affected people may develop seizures shortly after birth. These are characterized by infantile spasms (hypsarrhythmia). Mental retardation becomes evident as infants begin to miss their normal developmental milestones .

Infants may have heart tumors (rhabdomyoma), which can be detected by ultrasound. These tumors may grow or shrink and usually do not cause problems.

Several different skin lesions are common in tuberous sclerosis.

• "Ash leafs" are depigmented or hypopigmented (lacking normal skin color) white lesions that have the shape or appearance of an ash leaf and may appear anywhere on the body.
• Shagreen patches : These appear on the lower back as raised patches of skin with an orange-peel texture.
• Adenoma sebaceum (angiofibroma): These lesions include red, highly vascular, lumps on the face that may resemble irritated acne . These enlarge with age and may run together (become confluent) to form larger patches.

The incidence is approximately 1 in 25,000-30,000 births. There are no known risk factors other than having a parent with tuberous sclerosis. In that case, each child has a 50% chance of inheriting the disease.

Symptoms

• Ash leaf spots of skin, less often cafe-au-lait spots are evident
• Shagreen spots of the skin, if present, likely on the back
• Red, highly vascular lumps on the face (adenoma sebaceum)
• Mental retardation
• Seizures
• Rough growths under or around fingernails and toenails
• Pitted dental enamel
• Kidney tumors

Signs and tests

• Examination of the eyes may show retinal abnormalities, pale patches, mulberry tumor or phakoma or astrocytoma (tumor).
• There may be some indications of heart abnormalities including abnormal heart rhythm (electorcardiogram) or tumor (rhabdomyoma) on ultrasound .
• An MRI of the head demonstrates tumors or benign "tubers" in the brain.
• A CAT scan of the head may reveal calcium deposits in the brain.
• The mouth may show rubbery growths in tongue or gingiva.
• Ultrasound of kidney may show cysts, fatty benign tumors or serious tumors.
• Ultraviolet light examination of the skin may show ash leaf spots not visible in ordinary light.
• There may be a family history of the condition. Genetic testing for either of two genes that can cause this disease (TSC1 or 2) may be available.

Treatment

There is no specific treatment for tuberous sclerosis. Treatment is tailored to the symptoms. Seizure medications are required for controlling seizures , which is often difficult. Special schooling or care is determined by the severity of mental retardation .

Adenoma sebaceum (small growths) on the face may be removed by laser treatment. These lesions tend to recur and repeat treatments will be necessary.

Heart tumors called rhabdomyomas commonly disappear after puberty so surgery is usually not necessary. Regular ultrasound of kidneys is important screening for adults to make that sure tumors do not grow.