Author(s): Dr Ian Coulson, Dermatologist, United Kingdom.
Edited by the DermNet content team.
This eighty year-old woman has had generalised itching for the last two months and more recently has developed lesions on both thighs.
There are blisters on the thighs ranging in size between 5 mm and 3 cm in diameter. Many are haemorrhagic.
The likely diagnosis is bullous pemphigoid. This is the most common of the acquired immunobullous disorders. Biopsy of an intact blister will show a sub-epidermal blister and there is likely to be an eosinophil-rich infiltrate in the dermis. The diagnostic test is direct immunofluorescence of perilesional skin, which will show a linear band of IgG at the basement membrane zone.
A drug history is important for two reasons — some drugs are implicated in the induction of pemphigoid (gliptins, immune checkpoint inhibitors loop diuretics, and penicillins) and drugs being taken for comorbidities may be important.
The mainstay of treatment includes super potent topical steroids locally to the inflamed areas, and oral tetracyclines which can act as steroid sparing agents.
Failure to suppress symptoms with the above may necessitate the use of oral corticosteroids or immunosuppressive therapies such as azathioprine methotrexate, mycophenolate, and newer biological agents.
