Recurrent blisters on the lip

A woman in her 40s presented with a two year history of intermittent sore areas on her right lower lip—the same places each time. This occurred roughly once a month. With each episode she experienced tingling, itch, and soreness, leading to ulceration and blisters. Every episode spontaneously settled after 3-5 days, each time with residual brownish discoloration for a few weeks that then faded.

She had a history of migraines every 3-4 months, had no known allergies, and took paracetamol and ibuprofen each time she had a migraine. She did not take any other medication. She was a non-smoker and worked in a brewery. She consumed alcohol—drinking approximately one glass a month of gin and tonic as part of tastings at work (usually 1-2 units of alcohol, with 200 mL of tonic water each time).

On examination, ulceration of the mucosal lip was visible (fig 1), as was swelling of the vermillion lip …