Blister due to immunobullous disease
The patient, aged in her 70s, had had isolated blisters for several months. Often they were blood-stained but usually without surrounding redness.
A biopsy showed IgG and C3 at the basement membrane suggesting bullous pemphigoid, but that condition usually occurs in the flexures and on the trunk, usually on a red itchy area of skin.
This was in fact epidermolysis bullosa acquisita (EBA), an immunobullous disease occurring at sites of trauma. Interestingly, the patient had noted oral lesions when she ate sharp potato crisps. Rare cases of EBA can be associated with Crohn’s disease and blood dyscrasias,