After some weeks he presented when a patchy urticarial-type rash developed. The GP asked whether he had used or eaten anything to which he might been allergic, but the patient thought this was unlikely. An oral antihistamine did, to an extent, ease his itch.
A couple of weeks later the patient was alarmed when widespread, tense blisters developed, particularly on his trunk, thighs and arms. Some of these were filled with clear or blood-stained fluid.
What is the diagnosis, management and differential diagnosis?
Diagnosis and management
A diagnosis of bullous pemphigoid was confirmed by direct immunofluorescence of fluid drained from a blister and biopsy for histology. Blood may also be checked for circulating IgG autoantibodies which are positive in 70 per cent of patients.
Bullous pemphigoid is thought to be a chronic autoimmune reaction affecting the basement membrane of the skin. It usually occurs in the middle aged or elderly and may occur in both men and women. It occasionally occurs in childhood.
The itchy crops of tense fluid-containing blisters may be preceded by an urticarial rash. Most commonly the rash presents symmetrically on the inner thighs and may spread to the limbs and trunk. Oral lesions can occur.
A positive diagnosis is important, prior to starting treatment, because treatment may need to continue for many months or years before long-term remission can be expected.High dosage oral steroids (prednisolone 40mg daily) continued until the condition is under control. Gradually the dose can then be reduced to maintenance levels.
Steroid-sparing agents such as azathioprine or methotrexate may be used.
A potent topical steroid may also be used on affected areas, and may reduce the requirement of oral prednisolone.
Secondary infection of the blistered area may occur, which can be treated with antibiotics.
Possible different diagnoses
- Pemphigus vulgaris
- Drug-induced bullous disorders
- Dermatitis herpetiformis
- Epidermolysis bullosa
- Rare autoimmune disease.
- Cause unknown but genetic factors play a part.
- Most common between ages of 50 and 60 but may occur at any age.
- Usually presents with painful lesions on mucosal areas of the mouth and genital areas.
- Flaccid blistered lesions on the skin quickly rupture causing painful erosions.
- Skin biopsy required to confirm the diagnosis.
Contributed by Dr Jean Watkins, a sessional GP in Hampshire