Immunobullous diseases

Bullous pemphigoid
The most common of the immunobullous conditions, bullous pemphigoid predominantly affects the older population usually occurring in the seventh or eighth decade. It affects men and women equally. The split in the skin is subepidermal leading to tense fluid filled blisters in which the roof of the blister is the full thickness of the epidermis (Figure 13.1). The split is triggered by the presence of a specific antibody, its action is directed at the basement membrane complex (probably the hemidesmosomes (see Biology of the skin). The blisters often occur in flexures and around 50% of patients have lesions on the mucous membranes, the mouth being most commonly affected (Wojnarowska et al., 2002). Prior to the blisters developing, it is usual for patients to experience an irritating erythematous rash which may look somewhat urticarial. The blisters themselves may be haemorrhagic (blood filled).

Diagnosis is usually confirmed by a biopsy which should be taken from the edge of a new blister. This will show the subepidermal split. Direct immunofluorescence will show the antibodies lining up along the basement membranes of the cells. The disease is self-limiting and blisters will eventually stop forming; however this may take years, so treatment is usually necessary and desirable.


Treatment
Intensity of treatment will depend on the severity of the disease. The overall aim of treatment is to suppress the symptoms of blister formation, pruritis and urticaria, so that quality of life is maintained. This is generally achieved by immunosuppression of some description. Because the patient population is generally elderly, the treatment of symptoms with potent immunosuppression can cause a level of morbidity or even mortality, thus treatments must be closely monitored and there is a significant need for expert nursing care.
For more mild to moderate disease control may be gained by the use of very potent topical steroids (particularly 0.05% clobetasol proprionate) alone. This may be sufficient to gain control and oral therapies may not be needed. A review of the evidence for BP treatment regimes shows that there is little consensus about exact levels of oral treatment (Wojnarowska et al., 2002). However, the evidence does indicate that oral corticosteroids (usually prednisolone) should be used to control new blister formation in severe forms of the disease. 1 mg/kg is the commonly recommended starting dose for extensive disease, although in reality the dosage may not be directly related to patient weight and a starting dose of 60 mg is often used. The quality of evidence of the effectiveness of any of the other oral therapies is low; azathioprine is the most common additional treatment used, but the studies looking at its steroid sparing effects are conflicting (Wojnarowska et al., 2002). However, it may be added into a treatment regime if steroids alone are not halting blister formation. In severe disease, topical therapies are often used alongside the oral therapy.

High doses of steroids in elderly patients are associated with significant levels of morbidity and occasionally mortality. Careful monitoring for glucose in the urine and increased blood pressure should be routine. Monitoring the patient’s temperature will help indicate if an infection is developing. Eroded areas should be swabbed and sent for culturing if there are signs of infection.

Helping patients to remain comfortable and managing the blisters are key nursing roles. New blister formation should be logged each day as a method of determining treatment efficacy, i.e. if treatment is working, the number of new blisters developing each day will reduce and eventually stop. New blisters need to be broken using minimal skin trauma. Making a small incision with a blade is more effective than lancing with a needle as the incision is less likely to reseal than a hole. The skin should be left in place in order to form a natural dressing over the dermis. If topical steroids are being applied to the lesions, it is easier to apply the product to a non-adherent dressing and then onto the skin – cream is preferable to an ointment. The dressing should be secured using a light bandage or cotton tubular bandage, not tape. Maintaining skin hygiene is important in view of the large areas of open skin. Daily bathing with an antiseptic emollient may be helpful, although no evidence could be found to support this. Bland petrolatum emollients (e.g. white soft paraffin/liquid paraffin) can be helpful to maintain skin comfort particularly in the old blister sites where the skin tends to be dry.

Treatment is gradually reduced over time and then stopped once it appears that the patient is in total remission. Wojnarowska et al. (2002) recommend that treatment is reduced every 1–2 months and also states that the appearance of the occasional lesion should not lead to increase in treatment, rather should be taken as an indication that the condition is not being over treated. It is possible for people to experience relapses after periods of remission at which point treatment may need to be introduced again.