Epidermolysis bullosa

Epidermolysis bullosa

Definition  :

Epidermolysis bullosa (ep-ih-dur-MOL-uh-sis buhl-LO-sah) is a group of skin conditions whose hallmark is blistering in response to minor injury, heat, or friction from rubbing, scratching or adhesive tape. Four main types of epidermolysis bullosa exist, with numerous subtypes. Most are inherited.

Most types of epidermolysis bullosa initially affect infants and young children, although some people with mild forms of the condition don't develop signs and symptoms until adolescence or early adulthood. Mild forms of epidermolysis bullosa may improve with age, but severe forms may cause serious complications and can be fatal.

There's currently no cure for epidermolysis bullosa. For now, treatment focuses on addressing the symptoms, including pain prevention, wound prevention, infection and severe itching that occurs with continuous wound healing.

Symptoms:


The primary indication of epidermolysis bullosa is the eruption of fluid-filled blisters (bullae) on the skin, most commonly on the hands and feet in response to friction. Blisters of epidermolysis bullosa typically develop in various areas, depending on the type. In mild cases, blisters heal without scarring.
Signs and symptoms of epidermolysis bullosa may include:

• Blistering of your skin — how widespread and severe depends on the type
• Deformity or loss of fingernails and toenails
• Internal blistering, including on the throat, esophagus, upper airway, stomach, intestines and urinary tract
• Skin thickening on palms and soles of the feet (hyperkeratosis)
• Scalp blistering, scarring and hair loss (scarring alopecia)
• Thin-appearing skin (atrophic scarring)
• Tiny white skin bumps or pimples (milia)
• Dental abnormalities, such as tooth decay from poorly formed tooth enamel
• Excessive sweating
• Difficulty swallowing (dysphagia)

When to see a doctor
Contact your doctor promptly if you or your child develops blisters, particularly if there's no apparent reason for them.

In some cases of epidermolysis bullosa, blistering may not appear until a toddler first begins to walk, or until an older child begins new physical activities that trigger more intense friction on the feet.

Call your doctor immediately if you or your child experiences problems swallowing or breathing.
Also seek immediate care if you or your child has been diagnosed with epidermolysis bullosa and develops signs of an infection around an open area of skin, including:

• Redness, heat or pain
• Pus or a yellow discharge
• Crusting
• A red line or streak under the skin, spreading outward from the wound
• A wound that does not heal
• Fever or chills

Blisters can lead to infection and deformity. Your doctor can show you how to care for them properly and advise you on ways to prevent them



Causes:


In most cases, epidermolysis bullosa is inherited. Researchers have identified more than 10 genes involved with skin formation that, if defective, may cause a type of epidermolysis bullosa. It's also possible to develop epidermolysis bullosa as a result of a random mutation in a gene that occurred during the formation of an egg or sperm cell.

Your skin comprises an outer layer (epidermis) and an underlying layer (dermis). The area where the layers meet is called the basement membrane zone. Where and when blisters develop depend on the type of epidermolysis bullosa.

The four main types of this condition are:

• Epidermolysis bullosa simplex. This most common and generally mildest form usually begins at birth or during early infancy. In some people, mainly the palms of the hands and soles of the feet are affected. In epidermolysis bullosa simplex, the faulty genes are those involved in the production of keratin, a fibrous protein in the top layer of skin. The condition causes the skin to split in the epidermis, which produces blisters, usually without scar formation.
  
  If you have epidermolysis bullosa simplex, it's likely you inherited a single copy of the defective gene from one of your parents (autosomal dominant inheritance pattern). If one parent has the single faulty gene, there's a 50 percent chance that each of his or her offspring will have the defect.
  
  
• Junctional epidermolysis bullosa. This usually severe type of the disorder generally becomes apparent at birth. In junctional epidermolysis bullosa, the faulty genes are involved in the formation of thread-like fibers (hemidesmosomes) that attach your epidermis to your basement membrane. This gene defect causes tissue separation and blistering in your basement membrane zone.
  
  Junctional epidermolysis bullosa is the result of both parents carrying one copy of the defective gene and passing on the defective gene (autosomal recessive inheritance pattern), although neither parent may clinically have the disorder (silent mutation). If both parents carry one faulty gene, there's a 25 percent chance each of their offspring will inherit two defective genes — one from each parent — and develop the disorder.
  
  
• Dystrophic epidermolysis bullosa. This type, whose subtypes range from mild to severe, generally becomes apparent at birth or during early childhood. In dystrophic epidermolysis bullosa, the faulty genes are involved in the production of a type of collagen, a strong protein in the fibers that hold the deepest, toughest layer of your skin together. As a result, the fibers are either missing or nonfunctional. Dystrophic epidermolysis bullosa can be either dominant or recessive.

Epidermolysis bullosa acquisita (EBA) is another rare type of epidermolysis bullosa, which isn't inherited. Blistering associated with this condition occurs as the result of the immune system mistakenly attacking healthy tissue. It's similar to a condition called bullous pemphigoid, which also is related to an immune system disorder. EBA has been associated with Crohn's disease, an inflammatory bowel disease.

Complications:

In its more-severe forms, epidermolysis bullosa can have serious complications and can be fatal. Possible complications include:

• Secondary skin infection. Blistering can leave skin vulnerable to bacterial infection, particularly staph infection, and increase your chances for sepsis.
  
• Sepsis. Sepsis occurs when bacteria from a massive infection enter your bloodstream and spread throughout your body. Sepsis is a rapidly progressing, life-threatening condition that can cause shock and organ failure.
  
• Deformities. Severe forms of epidermolysis bullosa can cause fusion of fingers or toes and abnormal bending of joints (contractures), such as fingers, knees and elbows. Special bandaging wrapped between the fingers is often used to protect the fingers and prevent this complication.
  
• Malnutrition. If you or your child has a form of epidermolysis bullosa that causes blistering of the mouth and other mucous membranes, eating may be difficult. The resulting malnutrition can inhibit normal growth. Children with severe epidermolysis bullosa often improve with placement of a feeding tube (gastrostomy tube) so that they can receive supplemental nutrition.
  
• Anemia. Continuous loss of blood from open sores and possibly inability to take in adequate nutrition may contribute to iron deficiency anemia, but the true cause is unknown.
  
• Eye disorders. Inflammation in the mucous membrane (conjunctiva) that lines your eyelids and part of your eyeballs can lead to erosion of the transparent, dome-shaped surface of your eyes (cornea) and, sometimes, blindness.
  
• Skin cancer. As adolescents and adults, people with certain types of epidermolysis bullosa are at high risk of developing a type of skin cancer known as squamous cell carcinoma.
  
• Death. Infants who have a lethal form of junctional epidermolysis bullosa are at high risk of infections and loss of body fluids from widespread blistering. Their survival also may be threatened because of blistering of internal organs, which may hamper their ability to get enough nourishment and, sometimes, to breathe. Many of these infants die in childhood. Milder forms of epidermolysis bullosa, however, may not affect life expectancy.
  
• Constricted esophagus. A continuous cycle of blistering and scarring may cause narrowing in the esophagus, making it difficult to swallow. Surgical dilatation of the esophagus can relieve this and make it easier for food to travel from your mouth to your stomach.
  
• Hoarse voice. Blisters and scarring in the throat and esophagus may cause a hoarse voice or hoarse-sounding cry in babies.

Treatments and drugs:

Treatment of epidermolysis bullosa aims mainly at preventing complications and easing discomfort from blistering.

Skin care
Blisters may be large and, once broken, susceptible to infection and fluid loss. Your doctor may recommend the following tips for treating blisters and raw skin:

• Puncture blisters with a sterile needle to prevent the blister from spreading further. Leaving the roof of the blister intact allows for drainage of the blister while protecting the underlying skin.
  
• Apply antibiotic ointment, petroleum jelly or other moisturizing substance before applying a special nonsticking bandage.
  
• Soak wounds with a disinfectant solution. For wounds that don't heal, infection with bacteria such as pseudomonas may be playing a role. Soaks with diluted vinegar solution are sometimes used as a disinfectant, starting with a low enough concentration that the solution doesn't sting but is still helpful to remove germs.

Surgery
Ideally, deformities and fusion of the hands and feet can be prevented with daily protective wrapping. However, repeated blistering and scarring can cause deformities, such as fusing of the fingers or toes or abnormal bends in the joints (contractures). Your doctor may recommend surgery to correct these deformities, particularly if they interfere with normal motion.

Blistering and scarring of the esophagus may lead to esophageal narrowing, making eating difficult. Surgery to widen (dilate) the esophagus may be needed. Using light sedation, the surgeon positions a small balloon in the esophagus and inflates it to dilate the area.

To improve nutrition and help with weight gain, a tube (gastrostomy tube) may be implanted to deliver food directly to the stomach. Feedings through the tube may be delivered overnight using a pump. Eating through the mouth is continued if possible so that the child will be able to eat with others for normal socializing.

Physical therapy
Working with a physical therapist can help ease the limitations on motion caused by scarring and shortening of the skin (contracture). Swimming may be helpful for many people.
Intensive studies are under way to find better ways to treat and relieve the symptoms of epidermolysis bullosa, including gene replacement, bone marrow transplantation and recombinant protein therapies.