SKINIPEDIA - Skin Encyclopedia Studies: Bullous Pemphigoid
Bullous Pemphigoid Skin Disease Study by
Lawrence S Chan, MD, Dr Orville J Stone Professor of Dermatology, Head, Department of Dermatology, University of Illinois College of Medicine
(Part III)
Laboratory Studies
To establish a diagnosis of bullous pemphigoid, the following tests should be performed: histopathologic analysis from the edge of a blister and DIF studies on normal-appearing perilesional skin. If the DIF result is positive, indirect immunofluorescence (IDIF) is performed using the patient's serum. The preferred substrate for IDIF is salt-split normal human skin substrate.
Direct immunofluorescence studies
DIF studies demonstrate in vivo deposits of antibodies and other immunoreactants, such as complement. DIF tests usually demonstrate IgG (70-90% of patients) and complement C3 deposition (90-100% of patients) in a linear band at the dermal-epidermal junction. This pattern of immunoreactants is not specific for bullous pemphigoid and may be seen in cicatricial pemphigoid and epidermolysis bullosa acquisita. Bullous pemphigoid can be differentiated from these conditions by incubating the patient's skin biopsy sample in 1 mol/L salt prior to performing the DIF technique. This process induces cleavage through the lamina lucida. DIF on salt-split skin reveals IgG on the blister roof (epidermal side of split skin) in patients with bullous pemphigoid, while, in CP and EBA, the IgG localizes to the blister floor (dermal side of split skin).
The optimal location for DIF testing is normal-appearing perilesional skin. False-positive results can be observed when it is performed on lesional skin. Rarely, skin biopsy samples placed in transport media may yield false-negative results. This observation makes the use of fresh tissue the preferred substrate for DIF studies.
Indirect immunofluorescence
IDIF studies document the presence of IgG circulating autoantibodies in the patient's serum that target the skin basement membrane component. Seventy percent of patients with bullous pemphigoid have circulating autoantibodies that bind to split skin. The titer of circulating antibody is not correlated with the disease course.
IDIF studies can be used to detect the patient's IgG circulating autoantibodies that bind to the epidermal roof (upper part) of the salt-split skin substrate. .
Medical Care
As in other autoimmune bullous diseases, the goal of therapy is to decrease blister formation, to promote healing of blisters and erosions, and to determine the minimal dose of medication necessary to control the disease process. Therapy must be individualized for each patient, keeping in mind preexisting conditions and other patient-specific factors.
Treatment of patients with bullous pemphigoid requires coordination of care between the dermatologist and the patient's primary care provider. Patients with oral disease may require an otolaryngologist and/or a dentist for evaluation and care. An ophthalmologist should evaluate patients with suspected ocular involvement and those requiring prolonged high-dose steroids.
Diet
The lesions may flare in patients with oral disease after eating hard and crunchy foods, such as chips, raw fruits, and vegetables.
For patients treated with systemic corticosteroid for longer than 1 month, a combined supplement of calcium and vitamin D should be instituted to prevent osteoporosis. The dosage and the frequency are stated in the recommendations established by the American College of Rheumatology Task Force in 1996.
In addition to calcium and vitamin D supplementation, patients on long-term treatment with systemic corticosteroids should be taking bisphosphonate, a specific inhibitor for osteoclast-mediated bone resorption (eg, alendronate).
Patients should be instructed to avoid direct physical trauma to their skin surfaces. For example, localized bullous pemphigoid has rarely been described peristomally.
Medication
Treatment is directed at reducing the inflammatory response and autoantibody production. Although target-specific therapy is the "Holy Grail" for immunodermatologists, non–target-specific treatments are currently used. The most commonly used medications are anti-inflammatory agents (eg, corticosteroids, tetracyclines, dapsone) and immunosuppressants (eg, azathioprine, methotrexate, mycophenolate mofetil, cyclophosphamide). An article from Europe provided evidence that strong topical corticosteroid treatment may achieve disease control while avoiding systemic adverse effects from systemic corticosteroids.
Proper treatments of bullous pemphigoid depend on the severity of the disease. For localized disease, topical steroids plus the systemic anti-inflammatory (tetracycline and nicotinamide) may be sufficient. Effects of monotherapy with nicotinamide are unknown. For more severe cases, systemic steroids along with immunosuppressives may be needed to control the disease. If the disease is difficult to control, consider treatment with an anti-CD20 antibody (rituximab), which is relatively specific in targeting the antibody-producing B cells.
SKINIPEDIA, your Skin Encyclopedia Home