Bullous pemphigoid

Bullous pemphigoid, also referred to as BP, is an acute or chronic autoimmune skin disease, involving the formation of blisters, more appropriately known as bullae, at the space between the skin layers epidermis and dermis.

Signs and symptoms
Clinically the earliest lesions may appear urticarial (like hives). Tense bullae eventually erupt, most commonly at the inner thighs and upper arms but the trunk and extremities are frequently both involved. Any part of the skin surface can be involved. Milia are more common with epidermolysis bullosa acquisita (EBA), because of the deeper antigenic targets. A more ring-like configuration, with a central depression or centrally collapsed bullae may indicate linear IgA disease. The disease may be acute, but typically will wax and wane.

Causes
There are a number of potential causes including Ibuprofen.

Pathophysiology
The bullae are formed by an immune reaction, initiated by the formation of IgG autoantibodies targeting the type XVII collagen component of hemidesmosomes. It can also rarely involve the mucous membranes. Following antibody targeting, a cascade of immunomodulators results in a variable surge of neutrophils, lymphocytes and eosinophils coming to the affected area. Unclear events subsequently result in a separation along the dermal-epidermal junction and eventually stretch bullae.

Diagnosis
Diagnosis is based on two biopsies of the skin, one submitted for routine H&E staining and one for immunofluorescence studies.

Treatment
Treatments include Class I topical steroids (clobetasol, halobetasol, etc.) which in some studies have proven to be equally as effective as systemic, or pill, therapy and somewhat safer. However, in difficult to manage or widespread cases, systemic prednisone and powerful steroid-free immunosuppressant medications such as methotrexate, azathioprine or mycophenolate mofetil may be appropriate.

Epidemiology
Many mammals can be afflicted, including dogs, cats, pigs, and horses, as well as humans. Very rarely seen in children, it usually occurs in people 70 years of age and older. It is very rare in dogs; on average, three cases are diagnosed around the world each year.

At least one study indicates the incidence might be increasing in the United Kingdom.