Epidermolysis bullosa

What is epidermolysis bullosa?

Epidermolysis bullosa (EB) is a group of inherited diseases that are characterised by blistering lesions on the skin and mucous membranes. These may occur anywhere on the body but most commonly appear at sites of friction and minor trauma such as the feet and hands. Blisters may also occur on internal organs, such as the oesophagus, stomach and respiratory tract, without any apparent friction.

Epidermolysis bullosa

Lower 3 images provided through Swinfen Charitable Trust, by Dr Taha, Erbil, Iraqi Kurdistan.

EB should be distinguished from epidermolysis bullosa acquisita (EBA), which is an autoimmune blistering disease that is not inherited and often doesn't develop until adult life.

The EB conditions result from genetic defects of molecules in the skin concerned with adhesion. Loss of adhesion results in blister formation. There are 3 major types of EB based on different sites of blister formation within the skin structure:

EB Type	Site of blister formation within skin
Epidermolysis bullosa simplex (EBS)	Epidermis or uppermost layer of skin cells (keratinocytes)
Junctional epidermolysis bullosa (JEB)	Lamina lucida within the basement membrane zone (layer lying between the epidermis and dermis)
Dystrophic epidermolysis bullosa (DEB)	Lamina densa and upper dermis (deeper layers of skin cells)

Within each of these types of EB there are various subtypes. Varying degrees of severity that range from mild to severe are found with each EB type.

Who gets epidermolysis bullosa?

EB is an inherited disease, which means that you have inherited one or two EB genes. In autosomal dominant EB, only one abnormal gene is needed to express the disease. This means only one parent needs to carry the EB gene. On the other hand, autosomal recessive inherited EB requires you to have two EB genes (one from each parent) to have the disease. If a person has one recessive EB gene paired with a normal gene they are called a carrier and do not have the disease.

EB usually occurs at birth or shortly after. Males and females are equally affected. Occasionally EB may be mild enough at birth not to be apparent and it is not until the child is older or reaches adulthood before it is detected.

What are the clinical features of epidermolysis bullosa?

Epidermolysis bullosa simplex (EBS)

EBS Subtypes	Features
Weber-Cockayne	Most common and localised form of EBS Blisters develop on hands and feet in response to friction Usually presents in infancy as child is starting to crawl and walk Wounds heal without scarring but there may be thickening of the skin on soles and palms
Koebner	Generalised EBS where blisters develop all over the body but commonly on hands, feet and extremities Presents at birth or early in infancy May be mild involvement of mucous membranes and nails Thickening of skin and plaques develop on palms and soles
Dowling Meara	Generalised and severe form of EBS Present at birth with blistering on the face, trunk and limbs Thickened skin may cause calluses that limit or interfere with joint movement Nails often affected May involve other organs including inside the mouth, gastrointestinal and respiratory tract Widespread involvement may cause death in infancy but usually there is significant improvement with age
EB with muscular dystrophy	Due to plectin mutation Variable degree of blistering followed later in life by muscular dystrophy Muscular dystrophy does not arrise in all cases with plectin mutation

Junctional epidermolysis bullosa (JEB)

JEB Subtypes	Features
Herlitz JEB	Generalised and most severe form of JEB where blisters appear all over the body and often involve mucous membranes and internal organs May only present at birth with small single blister but becoming more widespread soon after Hoarse cry or cough is indicative of internal organ involvement Complications such as infection, malnutrition and dehydration usually lead to early death in infancy Most cases are lethal within the first 12-24 months of life
Non-Herlitz JEB	Generalised blistering and mucosal involvement present at birth or soon after Scalp, nails and tooth more involved Complications such as infection, malnutrition and dehydration may cause death in infancy but those who survive clinically improve with increasing age
Generalised atrophic benign EB	Mild generalised blistering present at birth, usually with scalp, nail and teeth involvement Blisters heal with a distinctive atrophic appearance Blisters worsen in warmer climates
EB with pyloric atresia	Severe generalised blistering in conjunction with pyloric atresia at birth Prognosis is poor and usually results in death during infancy Some cases may be very mild and survive

Dystrophic epidermolysis bullosa (DEB)

DEB Subtypes	Features
Dominant DEB	Generalised blistering present at birth Blistering becomes localised to hands, feet, elbow or knees as child grows older and in response to friction Small white spots called milia are often present at healed but scarred sites
Recessive DEB	May present with severe blistering (Hallopeau-Siemens) or mild disease (non-Hallopeau-Siemens) Generalised severe blistering is more common and involves large areas of skin and mucous membranes Blisters heal but with scarring and deformity causing limited movement as fingers and toes may be fused together (mitten hands) Complications such as infection, malnutrition and dehydration may cause death in infancy and those that survive are at great risk of developing squamous cell carcinoma

Treatment of epidermolysis bullosa

There is no cure for EB. Treatment is symptomatic and the primary aim is to protect the skin and stop blister formation, promote healing and prevent complications. Because EB can affect so many different parts of the body, a team of medical specialists is usually required for overall care. When necessary, treatment with oral and topical medications may be prescribed by your doctor to assist healing or prevent complications.

The following are some general measures used in caring for a patient with EB.

• Maintain a cool environment and avoid overheating
• Use foam padding or sheepskins to help reduce friction on furniture such as beds, chairs and infant car seats
• Wear clothing made of soft non-irritating fabrics
• Pierce, drain and dress blisters to promote healing (this should be done only by people whom have received training on wound care)
• Try to avoid using nappies in infants with severe EB, instead place child on a clean pad