Bullous pemphigoid is a blistering skin disease which usually affects middle aged or elderly persons. It is an immunobullous disease, i.e. the blisters are due an immune reaction within the skin. Bullous Pemphigoid is a rare, autoimmune, chronic skin disorder characterized by blistering. This disorder occurs most frequently in elderly people. Generalized blistering occurs in and under the upper layers of the skin and usually subsides spontaneously within several
months or years. However, symptoms may recur. In some rare cases of Bullous Pemphigoid, complications such as pneumonia may develop.
Characteristically, crops of tense, fluid-filled blisters develop. They may arise from normal-looking or red patches of skin, and the blisters may be filled with clear, cloudy or blood-stained fluid. Bullous pemphigoid is usually very itchy. It may be localized to one area but is more often widespread, often favouring body folds. In severe cases, there may be blisters over the entire skin surface as well as inside the mouth. Prior to blistering, the red itchy patches may be thought to be a kind of dermatitis or urticaria.
Bullous pemphigoid is an autoimmune disease, which means something causes the immune system to attack healthy tissues in the body, in this case the skin. The immune system normally releases disease-fighting cells, called antibodies, to attack foreign invaders, such as infections. Bullous pemphigoid is thought to occur because IgG immunoglobulins (antibodies) and activated T lymphocytes (white blood cells) attack components of the basement membrane, particularly proteins associated with the hemidesmosomes. The proteins are within the NC16A domain of collagen XVII. Hemidesmosomes ensure the epidermal keratinocyte cells stick to the dermis to make a waterproof seal. The ‘autoimmune’ reaction to these proteins can be thought of as a type of allergy to one's own skin. In many patients, skin antibodies can also be detected circulating in the blood stream (positive indirect immunofluorescence).
A dermatologist can often make the diagnosis by examining the skin carefully. In most cases the diagnosis will be confirmed by a skin biopsy of a typical blister. Under the microscope, the pathologist can see a split between the outside layer of the skin, the epidermis, and the inside layer, the dermis. Direct immunofluorescence staining highlights antibodies along the basement membrane that lies between the epidermis and dermis.
Bullous pemphigoid can be chronic and mild without affecting the general health of affected individuals. Treatment of bullous pemphigoid can resolve with topical cortisone creams, but sometimes requires high doses of cortisone ("steroids") taken internally. Severe bullous pemphigoid can also require immune suppression drugs, such as azathoprine (Imuran). Other treatments that have been used for severe disease include intravenous immunoglobulin infusions, typically given monthly.
Recent research has indicated that large quantities of high-potency topical corticosteroids applied to the entire body surface were safer and more effective in controlling extensive bullous pemphigoid than oral corticosteroids. It was felt by the researchers that topical corticosteroids should now be the treatment of choice for bullous pemphigoid, particularly when the disease is not extensive.