Bullous Pemphigoid (BP) is an uncommon autoimmune skin disease which leads to a very
itchy hive-like rash and blisters. The blisters can occur anywhere on the body, but the underarms, arms, groins, and lower legs seem more commonly affected in my experience, sometimes limited to these areas alone. The mucous membranes are usually not involved. BP is characterized as a “disease of the elderly” because the average age of onset is over 60. It is typical for us to consult on a new patient with BP who is in their 80’s or 90’s. I believe that the prevalence of BP is increasing simply because of increasing longevity and our aging population.
Some patients and doctors confuse BP with a more serious disease called Pemphigus
Vulgaris (PV). It’s easy to understand how this could happen. There are some similarities: both names are unfamiliar-sounding because of their Greek origin; Pemphigoid actually means “Pemphigus-like”; both are autoimmune blistering skin diseases which may be treated with prednisone. That is where similarities stop. Here are some important differences: PV usually begins in younger adults, average about 45 years; mucous membranes–oral, genital, eye–are almost always involved; PV is more serious, is less responsive to therapy, and has a poorer prognosis; the biopsy and immunologic
testing results for PV are different from those of BP. Therefore, it is mandatory to distinguish between these two diseases.
It is fairly straightforward to establish with certainty the diagnosis of BP once it is suspected from the clinical scenario of the elderly patient with itchy skin blisters. A skin biopsy should be taken of a blister (without breaking the blister) or a hive. A second biopsy should be obtained from normal-appearing skin adjacent to the lesion in the first specimen. The first specimen is examined by the dermatopathologist to show the level of the blister-split in the skin. In BP, the split is just below the epidermis, or top layer of skin. The second normal-appearing skin specimen is studied for immunologic deposits. In BP, the diagnosis is confirmed when an antibody called IgG is found in a linear pattern along the junction of the epidermis and the second layer of skin called the dermis.
My comments about treatment are based on over three decades of personal experience and the 2012 Guidelines of the British Association of Dermatologists. The treatments of choice for BP are topical and systemic corticosteroids. Clobetasol ointment or gel may be sufficient for localized cases. I usually advise only applying the steroid to the itchy rash or blisters until they dry up or rupture. If the blister breaks or leaks fluid, I recommend stopping the steroid and apply a topical antibiotic such as Silvadene cream or mupirocin ointment (Bactroban). If the topical medications are not working, or there are just too many blisters to make this treatment practical, I initiate prednisone in low to moderate doses depending on the weight and other comorbidities of the individual, for example, 10-20 mg/day.
Many secondary or adjuvant therapies have been studied, discussed, and used empirically to treat BP where first-line treatments have failed or been poorly tolerated. Two of the most common ones are Nicotinamide (not nicotinic acid or niacin) and antibiotics. I haven’t had good luck with the nicotinamide as far as effectiveness, and sometimes the pharmacist substitutes niacin which causes flushing and makes matters worse. On the other hand, I have observed positive results with tetracycline, doxycycline, and minocycline. Aside from preventing or treating superficial infections that can develop in open healing blisters, they also exert an anti-inflammatory effect that has allowed me to reduce prednisone to very low doses or stop it completely without a relapse of itching or blisters.
I will only list the other drugs which have been used to treat BP that allow a gradual tapering of prednisone without a flare-up of the disease because they are difficult to use, carry more toxicity, and require closer safety monitoring: azathioprine (Imuran), dapsone, mycophenolate mofetil (CellCept), and methotrexate. I tend to avoid these drugs in the more fragile geriatric patients who are taking other medications for other diseases. Although BP can be quite a nuisance and interfere with the quality of life, it is believed to be a self-limited disease, that is, it may go into a spontaneous remission after months or years. That is why I recommend the most conservative medication regimen that palliates the condition.