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Epidermolysis Bullosa

Epidermolysis bullosa (EB) is the term applied to a spectrum of rare genodermatoses in which a disturbed coherence of the epidermis of skin and mucous membranes leads to blister formation following trauma. Hence, the designation mechano-bullous dermatoses; there are more than 20 different types. Disease manifestations range from very mild to severely mutilating and even lethal forms that differ in mode of inheritance, clinical manifestations, and associated findings. The best classification is based on the site of blister formation and distinguishes among three main groups: epidermolytic or EB simplex (EBS), junctional EB (JEB), and dermolytic or dystrophic EB (DEB). In each of these groups there are several distinct types of EB based on clinical, genetic, histologic, and biochemical evaluation.

There are 3 major types of EB based on different sites of blister formation within the skin structure:

Epidermolysis bullosa simplex (EBS) :- EBS is defined as trauma-induced, intraepidermal blistering, based in most cases on keratin gene mutations. The two most common are dominantly inherited and described below :-

Generalized EBS Generalized EBS is the so called Koebner variant, with onset at birth to early infancy. There is generalized blistering following trauma with a predilection for traumatized body sites such as feet, hands, elbows, knees. Blisters are tense or flaccid at sites lead to erosions . There is rapid healing and only minimal scarring at sites of repeated blistering. Palmoplantar hyperkeratoses may be present. Nails, teeth, and oral mucosa are usually spared.

Localized EBS Also called the Weber-Cockayne subtype. Has an onset in childhood or later in life and is the most common form of EBS. Often the disease may not present itself. adulthood, when thick-walled blisters on feet and hands occur after excessive exercise, manual work or military training. Hypcrhydrosis of palms and soles, is associated and secondary infection of blistered lesions often occurs.

Junctional epidermolysis bullosa (JEB) :- All forms of JEB share the pathologic feature of blister formation within the lamina lucida of the basement membrane. This trait is autosomal recessive and comprises clinical phenotypes depending on the type of genetic lesion and environmental factors. There are at least six clinical subtypes, and the three principal forms are described below.

JEB Gravis (Berlitz EB) Patients with JEB gravis often do not survive infancy; the mortality rate is 40% during the first year of life. There is generalized blistering at birth with clinically distinctive and severe periorificial granulation tissue, loss of nails, and involvement of most mucosal surfaces. The skin of these children may be completely denuded, representing oozing painful erosion; and associated findings include all symptoms resulting from epithelial blistering with respiratory, gastrointestinal, and genitourinary organ systems involved.

JEB Mitis These children may have moderate or severe JEB at birth but survive infancy and clinically improve with age. Perioriticial non-healing erosions during childhood.

Generalized Atrophic Benign Epidermolysis Bullosa (GABEB) GABEB is a separate JEB that presents at birth with generalized cutaneous blistering and erosions not only on the extremities but also on the trunk, face, and scalp. Survival to adulthood is the rule, but blistering , traumatized areas continues . It is particularly pronounced with increased ambient temperature, and there is atrophic healing of the lesions. Nail dystrophy, non-scarring or scarrin. alopecia, mild oral mucous membrane involvment, and enamel defects occur. Mutations are in the gene for bullous pemphigoid antigen and laminin 5.

Dystrophic epidermolysis bullosa (DEB) :- DEB is a spectrum of dermolytic diseases where blistering occurs below the basal lamina, and therefore healing after blister formation is usually accompanied by scarring and milia for­mation-hence, the name dystrophic. There are four principal subtypes, and all are due to muta­tions in anchoring fibril type 7 collagen. Anchoring fibrils are therefore only rudimentary or absent. The four main types of dermolytic EB, but only two of these are described below.

Dominant DEB Dominant DEB is also called Cockayne-Touraine's disease. Onset in infancy or early childhood with acral blistering and nail dystrophy; milia and scar formation, which may be hypertrophic or hyperplastic. Oral lesions are uncommon, and teeth are usually normal.

Recessive DEB Recessive DEB (RDEB) comprises a larger spectrum of clinical phenotypes. There is a localized, less severe form (RDEB mitis) that occurs at birth, shows acral bliste­ing, atrophic scarring, and little or no mucosal involvement. Generalized, severe RDEB is mutilating and is called the Hallopeau-Siemens variant. There is generalized blistering at birth, and progression and repeated blistering at the same sites result in remarkable scarring, syndactyly with mitten like deformities of hand and feet.

Causes of 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.

Signs and symptoms of Epidermolysis Bullosa

Symptoms depend on the type of epidermolysis bullosa, but can include:

• Nail loss or deformed nails
• A hoarse cry, cough, or other respiratory difficulties
• Blistering in or around the mouth and throat, causing feeding difficulty or swallowing difficulty
• Dental abnormalities such as tooth decay
• Blistering around the eyes and nose
• Alopecia (hair loss)
• Blistering present at birth

Diagnosis

Treatment of Epidermolysis Bullosa

There is no therapy for EB. Management, therefore, has to be tailored to the severity and extent of skin involvement and consists of supportive skin care, supportive care for other organ systems, and systemic therapies for complications. Wound management, nutritional support, and infection control are key to the management of all EB patients.

Among persons with recessive dystrophic EB, the anticonvulsant phenytoin is sometimes effective because it decreases production of an enzyme that breaks down collagen.

Prevention of Epidermolysis Bullosa

• 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