A 76-year-old woman presents for evaluation of a long-standing sore just inside her lower lip. She has been referred by her dentist. The patient is otherwise in good health and denies any exposure history.
Although topical corticosteroids were ineffective, the patient did obtain some relief with topical tacrolimus. She received intralesional triamcinolone acetonide injections and, most recently, topical 5% dapsone was prescribed. Although topical dapsone is not indicated for lichen planus, oral dapsone has been reported to be effective in some patients.
Squamous cell carcinoma and leukoplakia are concerns; these would be ruled out by the biopsy. Aphthous stomatitis is also in the differential and would be ruled out by biopsy. Contact dermatitis would not be expected to be as focal as the lesion seen here; it would appear as a cheilitis rather than as an erosive lesion.