What is bullous pemphigoid?
Bullous pemphigoid (BP) is an autoimmune disease of the skin (reaction of the immune system to produce antibodies against the skin). It commonly affects people 60 years or older. It can affect men and women of all racial groups.
Why does bullous pemphigoid happen?
In people with BP, the immune system produces autoantibodies, which attack structures in the skin that holds the outer layer (epidermis) to the deeper layer (dermis) of the skin. This causes the layers to split and blisters to form. Blisters can happen on any part of the skin, and sometimes affect the mucosal surfaces, such as the mouth or genitalia. BP is not infectious (or contagious). It is also not due to allergies or affected by diet or lifestyle.
There are a number of medications that can lead to the development of BP. These drugs include diuretics (e.g. furosemide), antibiotics (amoxycillin and ciprofloxacin) and certain diabetes medications (e.g. DDP4 inhibitors or gliptins). In such cases, discontinuation of the implicated drug may result in significant and rapid improvement of BP. It is therefore essential to let your doctor know if you have been on any medication prior to the development of BP.
How does bullous pemphigoid present?
BP may present with an initial rash which can be like hives (swollen, red and itchy) or like eczema (scaly, red and itchy). When blisters occur, they usually appear on these hive or eczema-like rashes. Blisters can occur anywhere on the body. The blisters are large and tense, containing clear or blood-tinged fluid. They vary in size and may persist for several days before bursting to leave raw eroded areas. Blisters may occur in the oral cavity in 10-30% of patients.
How is bullous pemphigoid diagnosed?
The diagnosis of BP is made based on the typical presentation of tense blistering rashes, together with the following:
Skin biopsy of a blister for histology (microscope examination)
Biopsy of adjacent normal-looking skin or early lesions for immunofluorescence to check for presence of antibodies in the skin
Special blood tests to look for skin antibodies circulating in the blood
Can bullous pemphigoid be treated?
BP can be controlled with medications. BP tends to resolve in a few years. Treatment is important. Medications are needed to stop new blisters from occurring, promote healing of blisters present and to use the lowest possible dose needed to control the disease. Your compliance to the treatment plays an important role in controlling the disease activity.
The following are medications which are commonly used in the treatment this blistering disease:
Prednisolone is a steroid tablet that affects the immune system. It works fast and is used to get the disease under control quickly. It is usually prescribed as a single morning dose to be taken after food. Other dosing regime may be given by your doctors according to your needs. Common non-serious side effects of this drug include weight gain, facial puffiness, water retention and episodic blurring of vision. More serious side effects include increased susceptibility to infections, hypertension, diabetes mellitus, osteoporosis, glaucoma, cataracts, depression and peptic ulcer disease. While on this medication, your doctor will monitor your blood pressure, blood sugar or urine regularly. Bone mineral density scans may also be ordered for you on an annual basis. Do inform your doctor if you develop severe abdominal pain, black tarry/ sticky stools, visual disturbances, increased thirst or urination, mood disturbances, insomnia, fever, cough or other symptoms of being unwell.
Dapsone is actually an antibiotic. Its ability to modulate the immune system makes it useful in the treatment of BP. Its use can reduce the steroid requirement to control the disease activity of BP (i.e provide a “steroid[1]sparing” effect). As dapsone can cause red blood cells to break (haemolysis) and liver inflammation, you will be required to return early for blood tests as instructed by your doctor. Stop the medication and see your doctor immediately if you develop rashes during the first 2-6 weeks of taking the drug.
Azathioprine is also not a steroid tablet. It is an immunosuppressant, given together with steroids, to provide better control of the disease activity of BP and reduce the steroid dose (provide a “steroid-sparing” effect). Frequent blood tests will be required during the first few weeks of therapy. Side effects of azathioprine include increased susceptibility to infections, sterility, suppression of the bone marrow and liver toxicity. Avoid taking allopurinol (a drug commonly given for gout) while on azathioprine. See your doctor immediately if you develop abdominal discomfort below the lower right rib cage, a persistent sore throat or a prolonged fever.
Tetracyclines and nicotinamide may be given for milder cases of BP. Common non-serious side effects of these drugs include nausea, abdominal discomfort, vomiting and flushing.
