Lichen planus

Case history

A 70-year-old woman presented with a five-week history of a progressively worsening, very itchy rash on her trunk and limbs. It had started on her feet and legs and then spread to her forearms and hands. After two months, the rash had become widespread, and it was extensive by the time the patient presented to me. The rash consisted of many small, somewhat livid papules and plaques, some with a fine scale. On some sites there was a clear linear accumulation of the papules typical of a Koebner reaction. Mucosal sites, scalp and nails were not affected. Her family doctor had given her betamethasone dipropionate cream, but it had made no impact on the rash or itch. She was using no other medications.